Polymers doi: 10.3390/polym18101266

Authors: Jun-Xiang Xiong Zi-Han Yin Lian-Yi Qu Ying-Jun Xu

Zinc oxide nanoparticles (ZnO NPs) exhibit strong and broad-spectrum antibacterial properties, making them a promising agent for textile applications. However, their weak adhesion to fibers and poor washing durability have hindered practical use. In this work, we report zinc/catechol resin-based microspheres (Zn/CFRs) synthesized via a one-pot hydrothermal route and applied to cotton fabric through a pad-dry-cure process. The resulting Zn/CFRs exhibit a monodisperse spherical morphology, with zinc ions concentrated on the surface and ZnO NPs encapsulated within the resin matrix. The finished fabric demonstrates potent, non-leaching antibacterial activity, achieving over 99.99% inhibition against S. aureus, E. coli, and C. albicans, with excellent performance retention even after 50 laundering cycles. Furthermore, we observed that catechol oxidation in the Zn/CFRs proceeds slowly under UV light, which may contribute to the durable adhesion of the coating. Moreover, the functional finishing does not compromise the fabric’s tensile strength, hand feel, or breathability, which positions it favorably for scalable adoption in functional textile manufacturing.

Polymers doi: 10.3390/polym18101265

Authors: Halyna Ohar Maria Tokareva Viktor Tokarev

A novel macromolecular photoinitiator (MPI) was synthesized from a copolymer of maleic anhydride and methyl methacrylate and subsequently functionalized with 3-hydroxy-2-methoxy-1,2-diphenylpropan-1-one moieties via a polymer-analogous acylation reaction. The structure and physicochemical properties of the MPI were characterized by IR, UV–Vis, NMR, DSC, and TGA analyses. TiO2 nanoparticles were successfully functionalized with the MPI, yielding materials with enhanced surface activity and photoinitiating efficiency. The MPI-modified TiO2 facilitated efficient UV-induced polymerization of methyl methacrylate, as confirmed by DLS and SEM analyses. Compared with unmodified fillers, the resulting composites exhibited improved dispersion, accelerated polymerization rates, and enhanced mechanical properties. This hybrid strategy offers a promising approach for the development of high-performance polymer nanocomposites through the integration of surface-engineered inorganic fillers and photoreactive polymers.

Polymers doi: 10.3390/polym18101264

Authors: Ayad Lounas Yazeed A. Alsharedah Sadek Deboucha Yasser Altowaijri

Stabilizing weak soils is a well-known pavement and geotechnical engineering technique. This technique involves introducing minimal cementitious materials to improve the soil’s geotechnical characteristics. This paper investigates the use of recycled industrial polymer waste (IPW) as a reinforcement material in the presence of cementitious binders to stabilize weak silty sand soil (SM), supporting sustainable engineering practices. The randomly distributed IPW were added as percentages of 0%, 5%, and 10% to a mixture of lime soil and cement soil, with varying amounts of 0% to 6% of lime (L) and 0% to 6% of ordinary Portland cement (OPC), respectively. The laboratory experiments were conducted on natural and stabilized samples in wet (unsoaked) and submerged (soaked) conditions. The experimental program included Proctor compaction, California bearing ratio (CBR), unconfined compressive strength (UCS), durability tests, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction analyses. The resilient modulus (Mr) was estimated using an empirical equation. The outcomes of this experimental study show that adding a combination of IPW shreds with a small amount of L and/or OPC to the SM soil provides a significant increase in the UCS, CBR, durability and Mr values compared with case of SM with only L, which allows for superior characteristics and increases strength and stiffness parameters throughout any phase of earthwork construction design, resulting in stronger and stiffer subgrades. These results were reinforced by microstructural observations from SEM, EDS, and DRX, confirming the formation of cementitious gels and chemical compounds, consistent with the macro-scale mechanical improvements. The expected practical outcomes include potential reductions in pavement thickness, which can help lower pavement stabilization costs and extend its service life. Additionally, the use of waste materials to replace raw materials contributes to decreased energy consumption and emissions, although detailed assessments are needed to quantify these effects.

Polymers doi: 10.3390/polym18101263

Authors: Omer Fatih Sancak Muhammet Zeki Ozyurt Gamze Demirtas Sarah S. M. A. Sayed

The increasing use of low-density polyethylene (LDPE) has prompted growing interest in its application as a replacement for conventional aggregates in concrete. This study investigated the effects of replacing sand with 10%, 20%, and 30% LDPE granules in concrete. Compressive strength, splitting tensile strength, flexural strength, modulus of elasticity, slump, and density tests were performed. The results showed a gradual decrease in compressive strength (from 26.91 MPa in the reference mix to 16.56 MPa with 30% LDPE), tensile strength (from 2.46 MPa to 1.84 MPa), and flexural strength (from 3.37 MPa to 2.59 MPa). Decreases were also observed in modulus of elasticity, slump, and density values. However, LDPE-substituted concretes increased their axial and lateral strain capacities, showing improvement in ductility and deformation ability. Experimental results demonstrated a delicate balance between mechanical strength and sustainability benefits. It was demonstrated that low rates of LDPE substitution could balance performance with environmental advantages. The experimental results presented in this study were combined with previous research to create a dataset. Based on this dataset, exponential models predicting the properties of LDPE-substituted concrete and mortar were proposed. The proposed exponential models outperformed existing linear models in prediction accuracy, yielding coefficient of determination (R2) values up to 0.981 and significantly reduced mean absolute percentage error (MAPE) values, ranging from 1% to 17% depending on the dataset.

Polymers doi: 10.3390/polym18101260

Authors: Patricia Isabela Brăileanu Nicoleta Elisabeta Pascu Tiberiu Gabriel Dobrescu

This comprehensive review aims to cover the surface tribology and triboelectric properties of additively manufactured (AM) natural biopolymers, including cellulose, chitosan (CS) and silk fibroin (SF), in biomedical interface engineering. While these sustainable materials exhibit innate biocompatibility and tribopositivity, their baseline triboelectric performance demands targeted surface engineering. We synthesize key physical mechanisms governing charge generation, emphasizing how controlled surface roughness, hierarchical porosity and nanoscale architectures maximize contact electrification. Furthermore, distinct dielectric and polarity modulation strategies are evaluated across the biopolymer families: cellulose relies heavily on chemical functionalization to overcome weak native polarity; chitosan utilizes ionic coordination and fillers to elevate its relatively low charge density; and silk fibroin achieves exceptional power outputs via highly porous three-dimensional nanocomposite aerogels. AM technologies afford unprecedented spatial control over these biointerfaces but introduce severe processing constraints. Techniques such as those based on extrusion impose strict shear-thinning rheology and rapid crosslinking for cellulose and chitosan, while SF frequently suffers from crystallization-induced nozzle clogging, necessitating photocurable derivatives.

Polymers doi: 10.3390/polym18101262

Authors: Samah Maatoug Elham Abu Nab

CMCws is a low-cost, biodegradable carboxymethyl cellulose derived from Saudi wheat straw (CMCws) as a sustainable alternative to traditional sizing agents for cotton warp yarns. The effects of key sizing parameters—wet zone yarn tension (350–410 N), squeezing pressure (220–330 N/m), and machine speed (30–70 m/min)—on the weavability performance of CMCws-sized yarns were investigated by analyzing size add-on, tensile properties, hairiness, and abrasion resistance of sized warp yarns. Response surface methodology (RSM) based on a Box–Behnken experimental design comprising 15 runs was employed to optimize the machine settings and processing parameters for CMCws-sized yarns. Increasing wet zone yarn tension and squeezing pressure reduced size add-on and elongation at break, whereas higher sizing machine speed increased size add-on. Squeezing pressure showed a strong positive influence on abrasion resistance and adhesion power, while yarn hairiness increased with wet zone yarn tension and sizing machine speed. Maximum size add-on occurred at 70 m/min, 220 N/m, and 380 N, whereas optimum abrasion resistance was obtained at around 340 N, 330 N/m, and 45 m/min. Numerical optimization predicted minimum hairiness at about 350 N, 320 N/m, and 50 m/min. Overall, optimized settings significantly enhanced yarn mechanical performance and weavability, confirming CMCws as an effective, eco-friendly sizing agent for sustainable textile processing.

Polymers doi: 10.3390/polym18101261

Authors: Nan Zhang Yang Qiao Kaishan Yu Jinrong Zhang Pengfei Cui Chengzhao Yang Minglun Li

Protein molecularly imprinted polymers (MIPs), as artificial antibodies, are promising for protein separation due to their low cost, easy preparation, and high stability, but their performance is limited by poor mass transfer, imprecise imprinting, and single interaction modes. Herein, dendritic mesoporous silica nanoparticles (DMSNs) were used as the support, and a self-designed multifunctional poly(ionic liquid) macromonomer (p(VIMCD-co-VAIM-co-VSIM-co-VVIM)) served as the functional monomer to achieve directional anchoring of cytochrome C (Cyt-C). Surface-imprinted microspheres (DMSNs@MPS@PILs-MIPs) were prepared via free-radical copolymerization for Cyt-C recognition. The DMSNs possessed interconnected mesoporous channels, good dispersibility, an average particle size of ~80 nm, and a specific surface area of 267.97 m2/g. Ionic liquid monomers were synthesized via alkylation, and the macromonomer was constructed through a two-step method. Molecular dynamics simulations and spectroscopic characterization revealed the macromonomer-stabilized Cyt-C conformation, with interactions dominated by van der Waals forces. The DMSNs@MPS@PILs-MIPs featured a thin imprinted layer (~5 nm) to reduce mass-transfer resistance. Adsorption studies showed Cyt-C adsorption followed Langmuir and pseudo-second-order models, with a maximum capacity of 383.14 mg/g and an imprinting factor of 2.17. Only 12% capacity loss occurred after repeated cycles, indicating robust regeneration stability. This study provides a feasible strategy for constructing protein surface-imprinted polymers based on multifunctional synergistic interactions and conformational stabilization.

Polymers doi: 10.3390/polym18101258

Authors: Xiaobo Wan Kaizhen Wan Dongmei Zhao Yiming Liu Wenjing Cao Zongyi Deng Jian Li Zhixiong Huang Minxian Shi

This research developed a ZrSi2-TiB2-modified alumina fiber/boron phenolic resin ceramizable composite intended to fulfill the criteria for high-temperature resistance, oxidation resistance, and structural load-bearing capacity in reusable thermal protection systems. The composite exhibits a low thermal conductivity of 0.405 W·m−1·K−1, a reduced density of 2.11 g·cm−3, and a high mass retention rate of 89.45% after heat treatment at 1200 °C in air. During thermal cycling at 1200 °C with a 30 min dwell time, it consistently demonstrates excellent stability, mass retention, and mechanical properties, indicating its potential for applications in reusable thermal protection systems. Following 20 cycles, the variation in length and width remains below 0.6%, the mass retention surpasses 80%, and the flexural strength remains above 20 MPa after 15 cycles. Microstructural evolution and thermodynamic analysis disclose that the in situ ceramization reaction of ZrSi2 and TiB2 consumes oxygen, inhibits oxygen diffusion, and fills pores and microcracks with oxidation products (SiO2 and B2O3), thereby forming self-healing and densifying phases. This synergistic mechanism of self-healing and densification ensures the reusability of the composite. The research illustrates the performance evolution patterns and strengthening mechanisms of the composite under extreme thermal conditions, confirming its outstanding performance in repeated usage evaluations.

Polymers doi: 10.3390/polym18101257

Authors: Carlos Carpio-Cevallos Luis Chauca-Bajaña Andrea Ordoñez-Balladares Benjamín José Martín-Biedma Byron Velasquez Ron José Martín-Cruces

Background: Digital fabrication techniques such as CAD/CAM milling and 3D printing are widely used for provisional dental restorations. However, differences in mechanical performance remain controversial. Objective: To compare the hardness and flexural strength of CAD/CAM-milled resins versus 3D-printed resins used in restorative dentistry. Methods: A systematic review and meta-analysis were conducted following PRISMA 2020 guidelines and registered in PROSPERO (CRD420251045547). Electronic searches were performed in PubMed, Scopus, Web of Science, Embase, and LILACS. In vitro studies comparing CAD/CAM-milled and 3D-printed resins in terms of hardness and/or flexural strength were included. A random-effects inverse-variance model was applied using standardized mean difference (SMD) with 95% confidence intervals (CI). Risk of bias was assessed using the RoB-Iv tool. Results: Four studies (n = 124 specimens) were included in the hardness meta-analysis. CAD/CAM-milled resins showed significantly higher hardness (SMD = 2.92; 95% CI: 0.34–5.49; p = 0.026), although heterogeneity was high (I2 = 94.9%). Funnel plot asymmetry suggested possible small-study effects. For flexural strength, three studies (n = 40 specimens) were analyzed, demonstrating a significant effect favoring milled resins (SMD = 1.28; 95% CI: 0.42–2.14; p = 0.0036) with low-to-moderate heterogeneity (I2 = 27.8%). Sensitivity analyses confirmed robustness for both outcomes. Overall methodological quality was acceptable, with no high risk of bias identified in strength studies. Conclusions: CAD/CAM-milled resins tend to demonstrate higher hardness and flexural strength compared with 3D-printed resins. However, the substantial heterogeneity observed, particularly for hardness, and the potential influence of methodological variability, warrant cautious interpretation of these findings.

Polymers doi: 10.3390/polym18101259

Authors: Yuhuan Yuan Yangsheng Gao Debin Song Wei Xi Jia Huang Jiali Tang

This study systematically investigates the low-velocity impact response of aerospace-grade carbon-fiber-reinforced polymer (CFRP) T-stiffened panels. Through drop-weight impact tests at 20 J and 35 J energies and Cohesive Zone Model (CZM) numerical simulations, a comparative analysis was performed on two composite configurations: the pure CFRP baseline (Configuration A) and the hybrid configuration incorporating surface glass fiber layers (Configuration B). High-fidelity correlation between experimental and numerical results was achieved, validating the progressive damage evolution of the matrix and fiber constituents. The main findings demonstrate that the hybrid Configuration B exhibits significantly superior impact resistance compared to the monolithic CFRP Configuration A. The introduction of surface glass fiber layers produces a synergistic hybrid effect in the composite system. This surface layer acts as a protective buffer, effectively attenuating the impact load before it propagates to the underlying carbon fiber laminate. As a result, the hybrid structure absorbs more energy and effectively suppresses rapid crack propagation. Under 35 J impact energy, Configuration B avoids the brittle failure of the matrix observed in Configuration A, achieving a 24% increase in permanent energy absorption. This surface hybridization strategy provides an effective method for improving damage tolerance and preserving the structural integrity of advanced composite stiffened panels.

Polymers doi: 10.3390/polym18101256

Authors: Aiping Chen Saumitra Saxena Vasilios G. Samaras Bassam Dally

Recyclers worldwide face a common bottleneck: incoming mixed plastic bales are chemically opaque, yet the choice between mechanical recycling, chemical recycling, and energy recovery hinges on contaminant levels that cannot be judged by visual inspection alone. This study develops and validates a tiered analytical decision-support framework that translates standard laboratory measurements into explicit, actionable go/no-go routing criteria for any mixed polyolefin waste stream. The framework is organized into three successive analytical tiers of increasing specificity: Tier 1 uses FTIR and DSC for rapid polymer identification and thermal subclass confirmation; Tier 2 applies TGA/DTG for thermal stability assessment and filler quantification; and Tier 3 deploys ICP-OES, WD-XRF, CIC, and TG–MS for targeted heavy metal, halogen, and evolved gas profiling, triggered only when Tier 1/2 flags are raised. This staged logic minimizes unnecessary testing while ensuring that contaminant-relevant information is captured where it matters. The framework is demonstrated on nine blind mixed plastic waste streams (P1–P9) supplied by an industrial recycling facility without prior disclosure of polymer identity, filler content, or additive history—conditions that replicate the uncertainty encountered at any sorting plant globally. Application of the tiered protocol identified dominant polymers (HDPE, LDPE, PP), quantified inorganic fillers (CaCO3 up to ~38 wt%), and detected hazardous contaminants, including chlorine (up to ~1900 ppm), lead, chromium, and titanium, enabling each stream to be assigned to a specific recycling route with defined contaminant thresholds. Because the method relies exclusively on commercially available, vendor-independent instrumentation and follows a reproducible, rule-based decision logic, it is directly transferable to recycling facilities in any geographic context without site-specific calibration. The proposed framework thus provides a practical, scalable decision-support tool for feedstock-level quality control under emerging regulations such as the UNEP Global Plastics Treaty.

Polymers doi: 10.3390/polym18101255

Authors: Liubov Bodnar Tetiana Kovalova Volodymyr Yakovenko Oleh Koshovyi Kaloyan D. Georgiev Iliya Zhelev Slavov Liliia Vyshnevska

Microneedle systems represent a promising minimally invasive approach for transdermal drug delivery; however, their performance strongly depends on the composition and mechanical properties of the polymer matrix. The aim of this study was to select an optimal polymer composition for the fabrication of dissolving microneedle arrays produced by the mold casting method. The study focused on evaluating mechanical strength, dissolution behavior, and penetration efficiency of different polymer systems. Microneedle matrices were fabricated using polyvinylpyrrolidone (PVP K-30), methylcellulose, sodium alginate, and hyaluronic acid at various concentrations, alone and in combination. No active pharmaceutical ingredient (API) was incorporated; the study was performed using blank polymeric systems intended for subsequent drug loading. The microneedles were manufactured using 3D-printed and silicone molds. Their performance was evaluated by in vitro dissolution testing, pH measurement, penetration studies in gelatin gel and Parafilm M models, and mechanical compression testing. Monopolymer systems demonstrated either rapid dissolution with insufficient mechanical strength or improved strength at the expense of prolonged dissolution time. Combined polymer formulations showed superior structural uniformity and balanced performance. In particular, the system containing 5% PVP K-30 and 10% sodium alginate demonstrated the best overall characteristics, achieving high penetration efficiency (up to 96%), uniform dissolution (78%), and appropriate dissolution time (8.5 ± 0.5 min). Addition of hyaluronic acid further improved structural uniformity and handling properties. The results indicate that composite polymer matrices provide an optimal balance between mechanical stability, penetration ability, and dissolution rate. The formulation consisting of 5% PVP K-30 and 10% sodium alginate was identified as the most promising base for further development of drug-loaded dissolving microneedle systems.

Polymers doi: 10.3390/polym18101254

Authors: Yang Yang Chao Sun Xing Zheng Xinyu Li

The rapid advancement of flexible electronics technology has endowed flexible sensors with significant application potential in fields such as wearable sensors, bionic skin, and human–machine interaction, owing to their excellent conformability, stretchability, and comfort. However, as application scenarios continue to expand and deepen, higher requirements are imposed on sensor performance in terms of sensitivity, stability, biocompatibility, environmental friendliness, and multifunctional integration. Polyurethane composites, leveraging their intrinsic characteristics, including tunable molecular structure, superior flexibility, and good biocompatibility, can effectively impart properties such as electrical conductivity, self-healing capability, and high sensitivity through compositing with various functional materials, thereby precisely aligning with the diverse demands of next-generation flexible sensors. This article systematically reviews the synthesis strategies of polyurethane composites; provides a detailed analysis of the roles of fillers—including carbon-based materials, polymers, and metal nanoparticles/nanowires—in enhancing the mechanical, electrical, and functional properties of the composites; and further summarizes the research progress of polyurethane composite-based flexible sensors in cutting-edge areas such as eco-friendly sensing, human motion monitoring, health monitoring, and bionic electronic skin. Future development trends are also discussed, aiming to provide insights for the design and development of high-performance flexible sensors.

Polymers doi: 10.3390/polym18101253

Authors: Nitesh Subedi Alfredo Becerril Corral Md Monjur Hossain Bhuiyan Md Ariful Islam Zahed Siddique

This study investigates the pressure-dependent mechanical behavior and surface degradation of fluorocarbon elastomer (FKM, Viton®) O-ring seals following prolonged high-pressure hydrogen exposure. Specimens were aged at up to 7000 psi for 192 h and evaluated using tensile testing and optical image analysis. The results show a non-monotonic evolution of peak force, stiffness, and energy absorption, with increased load-bearing response at higher pressures accompanied by reduced displacement capacity. Normalized force–displacement behavior shows broadly similar loading profiles across pressure conditions; however, this representation is used for comparative visualization and does not establish preservation of the deformation mechanism. Image-based analysis reveals a significant increase in micro-defect density and surface heterogeneity with pressure, suggesting increased formation of surface micro-defects. These findings highlight pressure-dependent changes in polymer network response and surface morphology under hydrogen exposure. The study provides insights into structure–property relationships governing elastomer performance in hydrogen environments.

Polymers doi: 10.3390/polym18101252

Authors: Chan Gon Park Min Woo Park Byeong Ju Jin Ji Yeon Shim

This study investigates how the adhesive curing state before riveting influences material flow during riveting, joint formation, and the mechanical performance of CFRP/aluminum hybrid joints. Hybrid joints were fabricated in a single-lap configuration using electromagnetic self-piercing riveting (E-SPR) at curing times of 0, 20, 40, 60, and 80 min, and the adhesive distribution, joint geometry, load–displacement behavior, energy absorption, and failure mode were examined. As curing time increased, adhesive squeeze-out decreased and adhesive displacement during riveting was progressively restricted, leaving more adhesive near the contact point. Consequently, the head height increased from 0.12 to 0.21 mm, whereas the interlock distance decreased from 0.67 to 0.54 mm. In the bonded region, the peak load increased with curing time, and a peak load of 11.15 kN was observed at 40 min, indicating an increased contribution of the adhesive layer. In contrast, the load in the riveted region decreased at 60 and 80 min because the increased resistance of the adhesive interlayer limited the rivet deformation and mechanical interlocking. A maximum energy absorption of 32.13 J was observed at 40 min, where the joint exhibited relative contributions of the adhesive and the rivet. Failure analysis showed bearing failure at 40 min, whereas rivet pull-out was observed at 60 min, consistent with the curing-dependent changes in joint formation. These results indicate that curing-induced changes in adhesive behavior govern the interaction between adhesive flow and rivet deformation, thereby influencing joint formation and mechanical performance.

Polymers doi: 10.3390/polym18101251

Authors: Abdelrahman G. Gadallah Ahmed A. Bhran M. A. Farag A. S. Abdraboh A. A. Al-Esnawy

In this study, a streptomycin sulfate-loaded bioactive glass/chitosan (STRS–BG/CH) composite scaffold was fabricated via an improved unidirectional freeze-drying method, with drug loadings of 20–40%. The scaffolds were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis before and after in vitro testing. Antibacterial efficacy was evaluated against Gram-positive (Enterococcus faecalis, Staphylococcus aureus) and Gram-negative (Klebsiella pneumoniae, Escherichia coli) microorganisms via the agar diffusion method. The STRS–BG/CH scaffolds exhibited highly interconnected porous structures, prolonged antibacterial activity, and enhanced apatite-forming ability in vitro. Compared with bead-based carriers, scaffold-based systems provide enhanced structural integrity and interconnected porosity, which are advantageous for sustained drug release, apatite formation, and tissue integration. Accordingly, these multifunctional scaffolds may simultaneously provide localized antibacterial activity and potential relevance to bone tissue engineering applications. The prepared STRS–BG/CH scaffolds functioned as controlled release carriers for streptomycin sulfate while simultaneously maintaining antibacterial efficacy and bioactive performance. These results illustrate the importance of STRS–BG/CH scaffolds as a promising antibacterial bioactive scaffold system, warranting further biological investigation.

Polymers doi: 10.3390/polym18101250

Authors: Jingyu Gao Zhangyong Si Mengdi Xu Shengyu Zhang Fan Fan Feng Zhou Jiantao Zhang

Acne is a prevalent chronic inflammatory skin disorder with a high recurrence rate, in which Propionibacterium acnes (P. acnes) plays a key pathogenic role by colonizing subepidermal pilosebaceous units. The stratum corneum limits drug penetration, rendering conventional topical therapies ineffective. Herein, we report a detachable sustained-release microneedle system named Bacitracin@Hyaluronic Acid–Zein Microneedle (Bac@HA-ZMN) for localized antibacterial delivery in acne therapy. This microneedle patch consists of a dissolvable HA base and zein-based indwelling microneedle tips loaded with bacitracin (Bac) against P. acnes. Mechanical testing showed an average fracture force of 1.6 N per needle tip (n = 100), sufficient for skin insertion. The needle tips enabled Bac delivery to a depth of approximately 500 μm. In vitro transdermal studies demonstrated a cumulative release of 76.1% within 96 h, significantly higher than that of the control group (14.2%). In a murine acne model, the Bac@HA-ZMN treatment group showed a significantly smaller lesion area than the control group, and the immunohistochemical positive expression areas of the inflammatory factors IL-8, MMP-2, and TNF-α were reduced to 0.79%, 4.12%, and 2.14%, respectively, which was caused by the inhibitory effect of Bac on P. acnes. These results demonstrated Bac@HA-ZMN as a promising localized, sustained antibacterial delivery platform for acne treatment.

Polymers doi: 10.3390/polym18101249

Authors: Muhammad Irfan Saif Ullah Khan Wazir Muhammad Asif Khan Sarfraz Ahmed Zain Maqsood

Increased and excessive axle loads (exceeding design specifications) at high temperatures stimulate premature distresses in flexible pavements. This study utilizes the novelty of engineered bituminous composite—crumb rubber-modified (CRM) stone mastic asphalt (SMA) for pavement longevity and sustainable performance. Dynamic modulus testing was employed at four temperatures and six frequency sweeps. The experimental design included the preparation of SMA 19 specimens with six different percentages of crumb rubber (CR) mixed in bitumen. CR addition to the mix translated into an improved stiffness of the mix, as a 64% increase in dynamic modulus (on average) was reported at 10% CR as compared to a neat mixture. Master curves were produced using |E*| test results, which revealed that 10% modified SMA was relatively stiffer and more rut-resistant than the other mixtures. Performance prediction models were developed for |E*| using artificial neural networks (ANNs) and non-linear regression, wherein the former proved to be more robust. Sensitivity analysis revealed that a temperature rise (21.1 to 37.8 °C) translated into a 65% drop in |E*| (on average) and a rise in frequency (0.1 to 25 Hz) divulged a 72% upsurge in |E*| (on average). This research demonstrates the promise of deploying CR SMA mixtures, particularly for high-traffic and heavy-load scenarios.

Polymers doi: 10.3390/polym18101248

Authors: Nanshin Nansak Leo Creedon Denis O’Mahoney Ramen Ghosh Marion McAfee

The microstructure of semicrystalline bioresorbable polymers is central to their biomedical performance because the crystalline content influences both the mechanical stability and the degradation behaviour. Experimental studies have shown that crystallinity evolves concurrently with mass loss during enzymatic degradation. However, most existing models represent the material as a single homogeneous structure, preventing them from capturing this microstructural evolution or the state-selective mechanisms that drive it. We present a one-dimensional partial differential equation model for the enzymatic degradation of thin films, which treats the crystalline and amorphous states as distinct reactive components. Calibrated to poly(ε-caprolactone) (PCL) degraded by Candida antarctica lipase in vitro, the model accurately reproduces both the observed weight-loss profile and the concurrent decline in crystallinity. Parameter uncertainty analysis indicates that while there are varying degrees of confidence in individual parameter values, the overall model predictive uncertainty is well constrained. Parameter sensitivity analysis shows that the amorphous catalytic rate (the rate at which the enzyme degrades the amorphous region) is the dominant driver of degradation dynamics. The identified model parameters are used to explore the role of film thickness on the rates of mass and crystallinity loss. It was found that thin films remain largely reaction-limited, whereas thicker specimens become increasingly transport-influenced, with slower degradation and delayed structural evolution in the material interior. The model provides a useful tool to explore the effect of changing PCL film thickness on degradation rate and crystallinity-related properties without extensive experimentation.

Polymers doi: 10.3390/polym18101247

Authors: Abdullah Iftikhar Allan Manalo Mazhar Peerzada

Conventional epoxy polymers and their composites are increasingly challenged by environmental concerns, high manufacturing costs, and limited recyclability, necessitating the exploration of sustainable alternatives. Many research groups have sought to develop alternate polymers from various renewable resources, such as lignin, polyphenols, natural resins, saccharides, and plant oils. This new type of polymer has led to the emergence of bio-based polymers, which are often used with different reinforcements as bio-based composites. In this review, the synthesis of different bio-epoxy resins is discussed in detail along with their chemical structures. Subsequently, the enhancements in the properties of these bio-composites with the addition of different nanomaterials such as carbonaceous nanofillers (carbon nanotubes, graphene nanoplatelets, graphene oxide, etc.), cellulose-based nanomaterials, inorganic nano-silica (spherical and mesoporous), and nano-clay is explained. Lastly, the properties of these bio-composites and their applications in civil engineering are highlighted. This review has provided a detailed overview of the developments in bio-composites that can be used as a guide for the development of a new class of bio-composites using other alternate resources.

Polymers doi: 10.3390/polym18101246

Authors: Nergiz Kanmaz Nese Cakir Yigit Özlem Tuna

The development of durable and practical polymer-supported photocatalytic materials that are suitable for use in continuous-flow systems has become an increasingly pressing issue in the field of water treatment. In this study, FeTiO3/BiOCl heterojunction structures were synthesized at different ratios and integrated into a poly(vinylidene fluoride) (PVDF) matrix to develop photocatalytic thin-film systems. The resulting materials were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and UV–visible diffuse reflectance spectroscopy (UV-DRS) analyses. In photocatalytic experiments conducted under visible light, a 66.3% removal of doxycycline was achieved for pristine FeTiO3 within 180 min, whilst the FTO@BiOCl(III) composite reached 74.4%. In the PVDF-based thin-film system, the film catalyst demonstrated a removal efficiency of 68.9%. When the pH effect was investigated, the highest total removal of 90.3% was achieved under pH 6.0 conditions. Radical scavenging experiments revealed that superoxide radicals were the predominant active species (a decrease to 30.5% in the presence of benzoquinone (BQ). In experiments conducted in the air-lift reactor system, the P-FTO@BiOCl(III) film achieved approximately 65% removal after 9 h and maintained its structural stability. The PVDF-supported FeTiO3/BiOCl heterojunction thin-film system offers a noteworthy alternative for environmental applications due to its suitability for continuous systems, structural stability and effective photocatalytic performance.

Polymers doi: 10.3390/polym18101245

Authors: Lorenzo A. Picos-Corrales Grégorio Crini Elizabeth Carvajal-Millan

Biocompatible and biodegradable polymer materials offer essential properties in systems designed to protect human health, preserve food products, and improve water treatment, among other uses [...]

Polymers doi: 10.3390/polym18101244

Authors: Mengting Sun Zongsu Zhang Feng Liu Qigang Han

Advanced pultrusion technology for composite materials is an automated forming process that uses pre-impregnated materials as raw materials and is oriented towards the manufacturing of continuous components. It is particularly suitable for the continuous manufacturing of ultra-long components with uniform cross-sections and has a promising application prospect in the field of aviation composite materials. However, during the preforming stage, the pre-impregnated materials are prone to strain concentration and uneven thickness under the constraint of the mold surface, and in severe cases, there is a tendency to form wrinkles. Moreover, the severity of these defects is further influenced by the process parameters. In response to the above problems, this paper proposes a mold surface optimization method based on the finite element model with the goal of three-dimensional strain homogenization, which controls the thickness direction and in-plane strain within 5%, effectively improving the material deformation coordination. Furthermore, the influence law of preforming temperature, traction speed and tension on preforming quality was systematically analyzed through experimental research. It was found that the influence of each process parameter on appearance quality, thickness uniformity and internal quality all showed a trend of “improvement first and then deterioration”, thus obtaining a relatively better combination of process parameters for preforming quality. The results of this study provide methodological and technical support for the research on advanced pultrusion preforming processes of complex cross-section components.

Polymers doi: 10.3390/polym18101243

Authors: Suling Hu Yi Zhou Hongfan Hu Guoliang Mao Shixuan Xin

The incorporation of polar functional groups into polyethylene (PE) chains at controlled concentrations enables tailored multi-functionality, manifesting as printability enhancement, improved dyeability, and enhanced blending compatibility with diverse polymeric materials. The most effective way to incorporate polar monomers into the PE macromolecules is the transition metal-mediated coordination–insertion copolymerization of ethylene with polar monomers. However, the Lewis basic heteroatoms (N, O, S, P, etc.) in polar monomers are prone to strongly coordinate to the catalytic center, resulting in irreversible catalyst deactivation. Owing to the nature of tolerance to Lewis basic functionalities, rationally designed Pd and Ni complexes have proven to catalyze direct coordination polymerization of ethylene with polar monomers, which opened a practical way to prepare functionalized polyethylenes (F-PEs). In this context, we summarize the recent advances of the Pd and Ni complexes catalyzed copolymerization of ethylene with various polar monomers, especially focused on those commercial polar monomer feedstocks. In addition, the effects of metal, ligand structural modification, and additives regulation on the catalytic performances were analyzed in detail. Some key ideas on the salient aspects of the catalyst are presented, and the challenges and prospects of Pd and Ni catalysts in the polar monomer copolymerization problems are also discussed.

Polymers doi: 10.3390/polym18101242

Authors: Fotios Panagiotou Georgia Zafeiropoulou Franceska Gojda Kiriaki Chrissopoulou Ioannis Zuburtikudis Valadoula Deimede

Thin-film composite (TFC) polyamide (PA) nanofiltration membranes are the state of the art for water purification and reclamation, although a selectivity–permeability trade-off often restricts their development. To mitigate this problem, in this work, a novel three-layer structured nanofiltration (NF) membrane was fabricated consisting of a negatively charged poly (sodium 4-styrenesulfonate) (PSS) interlayer, a high-performance polyethyleneimine (PEI)-based PA separation layer and a PEI-grafted top layer. The PSS interlayer aimed to regulate interfacial polymerization (IP) of PEI with trimesoyl chloride (TMC) and enhance water transport, while PEI-grafting ensured high salt rejections. The relevant characterizations indicated that PEI-grafting endowed the resulting membrane (I-TFC-g) with a positive surface charge and increased the crosslinking degree to achieve much higher rejections for Mg+2 ions through the synergistic effect of Donnan and size-exclusion mechanisms, while the incorporation of the PSS interlayer resulted in an increased pure-water permeability (PWP) value of 7 L m−2 h−1 bar−1 (a value 2.8 times higher compared to the membrane TFC-g without a PSS interlayer). In specific, the I-TFC-g membrane displayed the highest salt rejections of 91% for MgCl2, 92% for MgSO4, 73% for Na2SO4 and 58% for NaCl and a good long-term stability. Overall, this work presents a simple strategy to improve NF performance by simultaneous enhancement of water permeability and salt selectivity.

Polymers doi: 10.3390/polym18101241

Authors: Xingxing Fang Haichang Guo Fei Yu Wei Zhang Qicheng Li Shulin Bai Peixun Zhang

Artificial nerve guidance conduits (NGCs) have gained significant attention in the field of peripheral nerve regeneration for the treatment of critically sized nerve defects. Nanotechnology-based NGCs are being explored as potential solutions for repairing and reconstructing peripheral nerve injuries due to their unique structure and topography. In this study, we present a novel core–sheath GelMA/PCL nanofiber construct fabricated through electrospinning and phase separation methods. The core–sheath GelMA/PCL nanofibers replicate the topological morphology of the native extracellular matrix (ECM). The outer layer, composed of GelMA, serves as an “adhesion domain” facilitating direct interaction with surrounding cells and tissues while improving wettability, integrin-mediated cell adhesion/attachment, and degradation. PCL, acting as the “elastic domain” within the nanofibers, enhances mechanical properties, maintains long-term stability of the NGCs, and enables controlled release of GelMA. Histomorphometric analysis along with electrophysiological and behavioral assessments demonstrate that these core–sheath GelMA/PCL nanofiber-based NGCs can activate endogenous mechanisms for peripheral nerve repair while promoting sensory/motor nerve regeneration and functional recovery. Overall, our findings demonstrate that GelMA/PCL nanofibers within the nuclear sheath can effectively remodel the nerve regeneration microenvironment by integrating “mechanical- biochemical” signals, thereby offering a novel strategy for addressing critical-size nerve defects.

Polymers doi: 10.3390/polym18101239

Authors: Rana Smaida Louis-Paul Maugard Hervé Gegout Manuel Arruebo Florence Fioretti Nadia Benkirane-Jessel Henri Favreau

Anterior cruciate ligament reconstruction relies on interference screw fixation, yet insufficient graft osseointegration remains a critical clinical challenge. This study aimed to develop and characterize a 3D-printed polymeric–hydroxyapatite composite interference screw with an osteoinductive surface to enhance localized osteogenic responses. Screws were designed, modeled, and fabricated using fused deposition modeling 3D printing with a polycaprolactone-poly(lactic-co-glycolic acid)-hydroxyapatite composite. Physico-chemical characterization was performed using scanning electron microscopy. Biocompatibility was assessed through mesenchymal stem cell metabolic activity assays and morphological analysis. Osteogenic gene expression was quantified by RT-qPCR following culture in osteogenic differentiation medium. In vivo osseointegration was evaluated histologically at five and nine weeks following implantation in the proximal tibial epiphysis of a rat model. 3D printing successfully produced screws with consistent geometry and surface characteristics. The composite material supported robust mesenchymal stem cell proliferation without cytotoxicity or morphological abnormalities. Histological examination revealed progressive bone formation with no adverse tissue reactions, including the absence of cyst formation, osteolysis, or excessive fibrosis. RT-qPCR revealed upregulation of osteogenic markers in those enhanced screws. These results indicate that the 3D-printed polymeric–hydroxyapatite composite screws are biocompatible and capable of stimulating localized osteogenic activity, supporting their potential as a biological foundation for future evaluation in anterior cruciate ligament reconstruction applications.

Polymers doi: 10.3390/polym18101238

Authors: José Roberto Vega-Baudrit Mary Lopretti

Tropical lignocellulosic residues are increasingly relevant feedstocks for lignin-containing nanocellulose composites, but their performance cannot be predicted from botanical origin or bulk lignin percentage alone. This review defines the interface as the geometrical boundary between phases and the interphase as the finite, compositionally graded region in which lignin distribution, nanocellulose morphology, adsorbed water, and the surrounding matrix jointly govern stress transfer and mass transport. Using an evidence-weighted framework, the literature is organized into the following categories: residual-lignin nanofibrils, redeposited-lignin systems, lignin nanoparticle assemblies, compatibilized thermoplastic hybrids, and all-lignocellulosic sheets. Representative quantitative observations show that controlled residual lignin can the increase water contact angle from approximately 35 degrees to 78 degrees and reduce oxygen permeability by up to 200-fold in nanopapers, while selected PLA/LCNF systems show tensile-strength and modulus increases of 37% and 61%, respectively; however, high or poorly distributed lignin can suppress fibrillation, lower viscosity, weaken gel networks, and reduce reproducibility. The most defensible near-term product windows are packaging layers, grease/oil barrier papers, coatings, paper-like multilayers, and selected porous media. Thermoplastic matrices remain process-sensitive, and biomedical, additive-manufacturing, nano-reactor, and energy-material claims require stronger validation of the extractables, rheology, humidity history, TEA/LCA metrics, and end-of-life behavior. This review, therefore, provides a critical, application-backward roadmap for tropical biorefineries in which interfacial function, wet handling, drying energy, and process integration are assessed together rather than treated as independent variables. The abbreviations used in the abstract are defined as follows: CNFs, cellulose nanofibrils; CNC, cellulose nanocrystals; LCNF, lignin-containing cellulose nanofibrils; LCNCs, lignin-containing cellulose nanocrystals; PLA, poly(lactic acid); PHB, polyhydroxybutyrate; PHAs, polyhydroxyalkanoates; PVA, poly(vinyl alcohol); DESs, deep eutectic solvents; TEA, techno-economic analysis; LCA, life-cycle assessment; ML, machine learning.

Polymers doi: 10.3390/polym18101240

Authors: Gönenç Duran

Barely Visible Impact Damage (BVID) in heterogeneous polymer-matrix composites remains difficult to detect because subtle damage signatures are often masked by complex architectures, hybrid textures, and overlapping failure morphologies. This study therefore presents an experimentally grounded, physics-aware, and statistically validated vision-based inspection framework rather than a purely detector-centered benchmarking exercise. Real post-impact images were obtained from controlled low-velocity impact experiments on 20 composite architectures and 60 physical specimens, yielding approximately 2000 images across laminated, hybrid, textile-reinforced, and sandwich structures. The dataset was organized using a specimen-disjoint splitting protocol to prevent leakage across training, validation, and test subsets. To improve robustness while preserving physical realism, a physically grounded Albumentations strategy was developed using only physically admissible transformations and explicit exclusion of non-physical operations that could distort damage morphology or surface continuity. Model development was further complemented by a hybrid hardware workflow in which cloud-based GPU training was combined with deployment-oriented inference profiling on resource-constrained edge-like hardware, thereby linking detection accuracy to practical industrial feasibility. In addition, model performance was evaluated under a standardized training budget and validated through repeated runs, Friedman significance testing, and Holm-corrected Wilcoxon signed-rank pairwise comparisons to ensure error-controlled interpretation of inter-model differences. Across the evaluated compact YOLO families, YOLO26s delivered the strongest overall performance, reaching 0.841 mAP@0.5, 0.586 ± 0.004 mAP@0.5:0.95, and an F1-score of 0.809, while YOLO11s achieved the highest precision and YOLO26n remained competitive in recall with nano-level compactness. Overall, the results show that experimentally generated heterogeneous composite data, morphology-preserving augmentation strategy development, leakage-aware dataset design, deployment-oriented computational profiling, and statistically grounded validation together provide a more robust and application-relevant basis for automated BVID detection in polymer-matrix composite structures.

Polymers doi: 10.3390/polym18101237

Authors: Danyun Lei Weiyi She Xiaoyu Chen Lei You Ying Zheng Byoung-Suhk Kim

Chitosan (CS) was employed to modify coconut shell activated carbon (CAC) to fabricate a composite adsorbent for wastewater treatment. By integrating the functional groups of CS with the high specific surface area of CAC through chemical modification, the resulting CS-AC composite exhibited significantly enhanced adsorption performance toward hexavalent chromium (Cr(VI)) in aqueous solutions. The effects of key parameters, including adsorbent dosage, initial Cr(VI) concentration, contact time, temperature, and solution pH on the adsorption efficiency were systematically investigated. Under optimal conditions, the CS-AC composite achieved a Cr(VI) removal efficiency of up to 99.04%. Kinetic and isotherm modeling revealed that the adsorption process followed the pseudo-second-order kinetic model and was well described by the Langmuir isotherm. Regeneration studies conducted over five consecutive adsorption-desorption cycles demonstrated that the composite retained a high removal efficiency of 98.10%, indicating excellent reusability. These findings suggest that the CS-AC composite is a promising and effective adsorbent for the removal of Cr(VI) from contaminated water.

Polymers doi: 10.3390/polym18101236

Authors: Haoran Shi Jun Qian Yifeng Shi

Acrylate hot-melt adhesives (AHMAs) are widely used in medical dressings, electronic components, and automotive interiors due to their solvent-free nature and high bonding strength. However, their wetting behavior on porous fabric substrates under varying coating temperatures—a critical factor for interfacial adhesion—remains poorly understood. To investigate how coating temperature affects the wetting and adhesion of acrylic hot-melt adhesives on fabric substrates, the apparent surface tension and viscosity of the adhesive (130–160 °C) and the apparent surface energy of the substrate (20–160 °C) were measured. By combining these measurements with contact angle decay curves on steel plates, scanning electron microscopy of cold-brittle cross-sections, and mechanical property tests, the study analysed the effects of temperature on wetting and spreading, penetration depth, and adhesive performance. Results show that with increasing temperature, adhesive surface tension and viscosity decrease, while fluidity improves; substrate surface energy shows no temperature dependence. The penetration depth into the fabric increases from 16 μm to 25 μm, and penetration uniformity gradually improves. However, both peel strength and loop tack continuously decrease with rising temperature, with optimal adhesion at 130 °C. A penetration depth model based on the Washburn equation effectively predicts the penetration behavior. Viscosity accounts for more than 50% of the effect, whilst the wetting factor contributes to a lesser extent. This study provides a theoretical basis for optimizing the coating process of acrylic hot-melt adhesives on fabric substrates.

Polymers doi: 10.3390/polym18101235

Authors: Aparna Sudarsana Babu Florian Zikeli Debora Puglia

The emerging demand for water pollution control has driven a significant interest in advanced porous materials for sustainable and effective wastewater treatment technologies. Metal–organic frameworks (MOFs) have been employed as promising substrates due to their versatile properties, especially their high surface area, tunable properties, and chemical functionality. However, their practical applications are often limited by poor aqueous stability, instability during recovery, and high production costs. Lignocellulosic biomass (LCB) is an abundant, low-cost, and renewable resource, primarily composed of cellulose, hemicellulose, and lignin, offering a sustainable solution for these challenges. This review critically examines the recent advances in design and applications of LCB-MOF materials for wastewater remediation. Several synthesis strategies, including in situ growth, ex situ impregnation, and post-synthetic modification, are systematically discussed in relation to their significance in enhancing stability, recyclability, and dispersibility of MOFs. The key, structural, morphological, and physicochemical properties of these LCB-MOFs were analyzed, along with their performance in removing organic dyes and heavy metal ions. Current drawbacks in long-term stability, scalability, and real-world wastewater performance are highlighted. Overall, LCB-MOFs demonstrate a promising class of sustainable materials that align with the principles of the circular economy and green chemistry, making them ideal for next-generation wastewater remediation technologies.

Polymers doi: 10.3390/polym18101234

Authors: Hailin Wang Haowei Lv Boliang Li Linyan Deng Yangyang Wen Hongyan Li

Food packaging constitutes a pivotal enabler within the contemporary food industry, requiring continuous innovation to address evolving challenges. Traditional packaging systems typically provide passive protection, which is inadequate for addressing dynamic microbial shifts and spoilage-induced microenvironmental instabilities. In contrast, corrective responsive food packaging (CRFP) takes a distinct approach through the integration of sensing capabilities and targeted active intervention. Upon detection of specific stimuli, CRFP systems precisely deliver bioactive agents to mitigate food deterioration. This review systematically summarizes recent advances in CRFP technology, offering a comprehensive overview of its core response mechanisms, functional materials, advanced carrier systems, and future research priorities. Special emphasis is given to (i) stimuli-responsive systems, including single-stimulus (pH, enzyme, humidity, temperature, and light) and multi-stimulus-responsive systems, detailing their triggering mechanisms and practical applications; and (ii) functional materials and carriers, exploring their synergistic effects for optimized bioactive release. This review aims to provide a structured framework for the design and implementation of CRFP, facilitating its translation from laboratory to industrial practice and contributing to the development of sustainable and efficient food preservation strategies.

Polymers doi: 10.3390/polym18101233

Authors: Derui Zhang Junpeng Ma Long Liu Yan Zhu Anfu Guo Peng Qu Shuai Guo Zengrui Song Yaqin Song Shaoqing Wang

Symmetric corrugated hierarchical honeycombs (SCHHs) are critical lightweight load-bearing structures, featuring distinctive topological architectures and excellent mechanical performance. However, they are prone to local buckling under out-of-plane compression and shear loading, which degrades their overall load-bearing capacity. To address this limitation, this work proposes an innovative dual-optimization strategy integrating cylindrical support structure introduction and nano-silica (SiO2) matrix modification to synergistically enhance the compressive and tribological properties of SCHHs. 3D-printed SCHHs and their reinforced variant (SCHH-AC) with embedded cylindrical supports were fabricated, and the effects of nano-SiO2 modification (0–9 wt.%) on the compressive performance and tribological behavior of the photopolymer resin matrix were systematically investigated. Experimental results demonstrate that the SCHH-AC-7% SiO2 configuration achieves optimal compressive performance. A critical SiO2 concentration threshold was identified: agglomeration at 9 wt.% induces severe mechanical degradation. Tribological tests confirm that SiO2 incorporation effectively reduces the resin matrix’s friction coefficient and wear rate, with the 7 wt.% concentration yielding the lowest wear rate. Additionally, geometric parametric analysis reveals that increasing the corrugation period number and amplitude further enhances SCHH’s compressive strength and energy absorption. This study establishes a theoretical and experimental foundation for the structural design and material modification of lightweight honeycombs, advancing their practical application in high-performance engineering fields demanding lightweight load-bearing and wear resistance.

Polymers doi: 10.3390/polym18101232

Authors: Zhen Li Zhiyun Han Xinkai Zhang Yizhou Xu Liang Zou Kejie Huang Hanwen Ren

Interfacial stress concentration induced by curing shrinkage during the manufacturing of epoxy resin is a primary trigger for micro-nano defect formation and electrical performance degradation in power equipment. To address the computational complexity of traditional viscoelastic models and the thermoelastic behavior wherein the stiffness of the epoxy resin varies with temperature during curing, this paper proposes an improved viscoelastic constitutive model incorporating a thermo-elastic factor. By coupling curing kinetics, heat conduction, chemical shrinkage, and mechanical effects, a multi-physics simulation framework is constructed to describe the complete epoxy curing process, thereby revealing the spatiotemporal evolution of curing stress deformation. To verify the model’s accuracy, an in situ monitoring system based on Fiber Bragg Grating (FBG) sensors was established. A temperature compensation method was utilized to effectively decouple temperature and stress within the complex exothermic curing environment. This study reveals a significant strain gradient effect during the resin curing process. Experimental measurements indicate strains of 21,609 με and 5800 με at the interface and surface, respectively, with numerical simulations exhibiting high agreement with the experimental data. This research not only provides an efficient simulation approach for predicting curing stress but also offers a theoretical basis for the crack-resistant structural design of high-performance epoxy-based power equipment.

Polymers doi: 10.3390/polym18101231

Authors: Hideki Kimura Yusuke Kobayashi Hirotaka Irie Kouhei Sagawa Helmut Takahiro Uchida Michael C. Faudree Michelle Salvia Yoshitake Nishi

Presently, there is little to no literature that investigates the effect of electron beams on para-aramid (Kevlar®) fiber polymer (KFRP) composites. Therefore, we assessed the effect of homogeneous low-potential electron beam irradiation (HLEBI) on Kevlar-reinforced recyclable thermoplastic (TP) polypropylene (PP) (KFRPP). Samples were assembled in an interlayered configuration of four-sized KF plies between five PP sheets [PP1-KF1-PP2-KF2-PP3-KF2-PP2-KF1-PP1] designated [PP]5[KF]4, which were hot-pressed at 493 K at 4 MPa for 7 min. Experimental results show when an HLEBI setting of 250 kV cathode potential (Vc) at an 86 kGy dose is applied to finished sample surfaces, the Charpy impact strength (auc) at median fracture probability (Pf of 0.50) is increased 59% from 72.5 kJ/m2 when untreated to 115.6 kJ/m2 thereafter, while a 170 kV–129 kGy setting increased auc about 15%, to 83.3 kJ/m2, when compared to the untreated sample. Scanning electron microscopy (SEM) showed the 250 kV–86 kGy HLEBI increases KF/PP adhesion with increased consolidation and KF bundling, while the electron spin resonance (ESR) showed HLEBI generates dangling bonds (DBs) in KF and PP, which is evidence of the strengthening KF/PP interface. X-ray photoelectron spectroscopy (XPS) of the N1s spectrum of Kevlar fiber from the fracture region of the untreated sample showed a dominant peak at 399.5 eV with 82.7% area, which is characteristic of the Kevlar backbone N–(C=O)–, indicating poor adhesion with fiber pullout. However, the dominant peak was shifted in the 250 kV–86 kGy sample to that of strongly bonded imines, –C=N–, at 398.6 eV and 36.8%, indicating strong bonds generated at the KF/PP interface. Together, the N1s, C1s and O1s spectra indicate increased polar groups, reduced weak Van der Waals forces, and the generation of a strong active nitrogen-containing interphase, acting to reduce fiber pullout to increase the impact strength of the [PP]5[KF]4 composite system.

Polymers doi: 10.3390/polym18101230

Authors: Vladimir Nedić Andreas Paul Marius Catalin Barbu Lubos Kristak

Industrial control of volatile organic compound (VOC) emissions from medium-density fibreboard (MDF) production remains constrained by a shortage of compound-resolved evidence from full-scale plants, where wood furnish, amino resin chemistry, heat transfer, gas flow, and wet gas cleaning act simultaneously. Here, we analysed more than 20,000 synchronized operating records from a full-scale single-stage flash-tube MDF dryer at an industrial SWISS KRONO production line and linked total VOC (TVOC) measurements from flame ionization detection with Fourier-transform infrared speciation on the cleaned stack. Five compounds—α-pinene, 3-carene, limonene, methanol, and formaldehyde—accounted for more than 80% of the resolved VOC signal. Process–state contrasts showed that higher digester residence time, discharge screw speed, adhesive amount, urea amount, dryer inlet temperature, and scrubber–water temperature increased one or more representative compounds, whereas higher hardwood share, additional flue-gas supply, and higher scrubber–water pH decreased them. Limonene, methanol, and formaldehyde were substantially more process-sensitive than α-pinene. An exploratory decorrelation step further showed that a drying/throughput domain explained about half of the variability of the screened process space. The study therefore identifies the small set of compounds and operating domains that most strongly govern the cleaned dryer-stack signature and provides a mechanistically grounded prioritization framework for follow-up causal experiments, source apportionment, and emission-mitigation design in industrial MDF manufacture. Unlike product or chamber emission studies, this work links the compound-resolved FTIR/FID chemistry of the final cleaned industrial stack with synchronized production variables; it therefore addresses a scale-integration gap by transforming routine compliance-type exhaust monitoring into a process-diagnostic framework for ranking emission sources, abatement-sensitive variables, and mitigation experiments.

Polymers doi: 10.3390/polym18101229

Authors: Behiç Selman Erdoğdu Muhammed İhsan Özgün Emrah Madenci Mehmet Ali Sayınbatur Fatih Erci

In this study, the structural, thermal, and mechanical properties of nanocomposites obtained by adding zinc oxide (ZnO) nanoparticles (NPs), produced by phyto-mediated synthesis using Dianthus chinensis plant extract, to a PMMA-based photopolymer resin at different ratios (0.05%, 0.10%, 0.15%, 0.20%, and 0.25%, by weight) were evaluated. The prepared composite resins were produced in different test geometries using a DLP (digital light processing)-based 3D printer (Asiga Ultra). Following the structural characterization of ZnO nanoparticles, tensile, compressive, and flexural mechanical tests were performed on the resulting composites, as well as FTIR, TGA, DSC, and DMA analyses. The FTIR results showed that ZnO NPs were physically integrated into the matrix. TGA and DSC analyses revealed that the addition of ZnO NPs, particularly at an addition rate of 0.15%, increased thermal stability. DMA analyses showed an increase in storage modulus and glass transition temperature as the addition rate increased. In mechanical tests, the highest modulus of elasticity and maximum strength values were obtained at additive ratios of 0.10–0.15%. The highest tensile strength (55.31 MPa) and compressive strength (388.53 MPa) were obtained at ZnO contents of 0.10–0.15 wt%, while the maximum flexural strength reached 125.94 MPa at 0.15 wt% ZnO. In addition, the storage modulus increased from 1.469 × 109 Pa for the control resin to 1.872 × 109 Pa for the composite containing 0.15 wt% ZnO, indicating improved stiffness and thermomechanical stability. The stress–strain curves show that improvements in ductility and deformation capacity of the material are achieved at these additive ratios. The findings demonstrate that green-synthesized ZnO nanoparticles are an effective and sustainable additive material for improving the mechanical and thermal performance of DLP-based photopolymer dental resins.

Polymers doi: 10.3390/polym18101228

Authors: Jinzhu Li Liwei Zhang Jinchao Qiao

This study investigates the influence of nano-alumina (nano-Al2O3) on the compressive properties and damage mechanisms of epoxy matrix composites across a wide strain rate range. Composites with varying nano-Al2O3 contents (0, 1, 3, 5, 10, 15 wt%) were tested under quasi-static (0.001~0.1 s−1) and dynamic (2500~4800 s−1) conditions using a universal testing machine and a Split Hopkinson Pressure Bar, respectively. The phase, the microstructure, and their effects on macro-mechanical performance and micro-damage were characterized by XRD, SEM, and TEM. Results indicate that the incorporated nano-Al2O3 is highly crystalline, single-phase lamellar α-Al2O3. Its addition significantly modulates the compressive properties, with effects dependent on both content and strain rate. Under quasi-static compression, yield strength increased monotonically with nano-Al2O3 content at 0.1 and 0.01 s−1, reaching a maximum increase of ~9.5% at 15 wt%. However, at 0.001 s−1, optimal strength occurred at 10 wt%, beyond which agglomeration caused degradation. Dynamic tests revealed a positive strain rate effect. The 10 wt% composite exhibited optimal overall performance, combining high peak stress and a stable stress plateau, whereas the 15 wt% sample showed higher peak stress but poor post-peak load-bearing capacity. Microstructural analysis showed that 10 wt% nano-Al2O3 dispersed uniformly, enhancing toughness by inhibiting crack propagation via interfacial bonding and microstructural refinement. In contrast, at 15 wt%, particle agglomeration induced interfacial defects, promoting debonding and brittle fracture. This work provides insights into the wide-strain-rate mechanical behavior of nanoparticle-reinforced polymers and supports the design of high-performance, impact-resistant epoxy composites.

Polymers doi: 10.3390/polym18101227

Authors: Monika Rojewska Emilia Jakubowska Klaudia Szelejewska Maja Nowaczyk Anna Froelich Krystyna Prochaska Tomasz Osmałek

Hydration, interfacial interactions, and matrix stability are critical determinants of the mucoadhesive behavior of cellulose-based polymers. In this study, we investigated the physicochemical and mucoadhesive behavior of hydroxypropyl methylcellulose (HPMC), Carbopol 974P NF, and Kollidon VA 64, along with their binary blends (1:1, w/w) in the context of oral mucosal drug delivery. Wettability, surface free energy, mucoadhesion, and hydration-induced morphological changes were systematically evaluated using contact angle measurements, adhesion and water uptake studies, and real-time surface dissolution imaging (SDi2). The investigated systems displayed markedly different water contact angles: HPMC 103.4 ± 2.7°, Carbopol 47.2 ± 2.3°, Kollidon 36.0 ± 1.8°, HPMC:Carbopol 51.3 ± 2.8°, and HPMC:Kollidon 53.9 ± 3.4°. The corresponding surface free energy (SFE) values ranged from 12.0 mJ/m2 for HPMC to 70.5 mJ/m2 for Kollidon. Experiments were performed under saliva-mimicking conditions containing 0.1% (w/v) mucin. The HPMC:Carbopol blend exhibited superior mucoadhesive performance and mechanical stability compared with HPMC alone or with the HPMC:Kollidon blends. In 2% (w/v) mucin, the HPMC:Carbopol blend reached a mucoadhesive force of approximately 1.35 N, whereas HPMC and HPMC:Kollidon showed lower values of approximately 0.5–0.75 N and 0.60 N, respectively. After 96 h at 85% RH, the swelling index increased from 14.8 ± 0.5% for HPMC to 29.4 ± 0.3% for HPMC:Carbopol. The incorporation of Carbopol increased the polar contribution to the surface free energy of HPMC-based blends and promoted stable gel layer formation, whereas Kollidon-containing systems underwent rapid disintegration and asymmetric deformation. SDi2 imaging showed that the HPMC disk changed proportionally by approximately 18% in both height and width during 12 h, whereas the HPMC:Kollidon disk almost completely dissolved after approximately 6 h. These results demonstrate that rational selection and combination of cellulose-based polymers can be used to control hydration, interfacial properties, and mucoadhesion, with HPMC:Carbopol blends showing strong potential for oral mucosal drug delivery.

Polymers doi: 10.3390/polym18101226

Authors: Likang Zhou Songjie Xu Junhao Fei Meng Ma Huiwen He Yanqin Shi Yulu Zhu Si Chen Xu Wang

The cross-linked network structure of epoxy resins gives them excellent mechanical properties and heat resistance. However, it also makes them difficult to reprocess and recycle. This leads to environmental pollution and resource waste. Dynamic covalent bonds can make epoxy resins reprocessable. However, this involves a hard trade-off: adding flexible segments improves processing stability at the cost of mechanical strength, whereas keeping a rigid backbone retains the initial strength but leads to incomplete network reformation after multiple reprocessing cycles. As a result, performance continues to decrease. To solve this problem, this paper proposes a new strategy. It combines rigid cross-linked networks with alkyl dangling chains. The strategy does not sacrifice the rigid backbone of the epoxy. Instead, the alkyl dangling chains form physical entanglements during reprocessing. These entanglements compensate for the loss of chemical cross-linking density. Thus, the mechanical properties are retained or even enhanced. A vanillin-based Schiff base epoxy system was used. Alkyl dangling chains of different lengths were compared, and the results show that the system with longer alkyl dangling chains had higher mechanical properties after three reprocessing cycles; its tensile toughness increased by 85.7% compared to the system without dangling chains. At the same time, its thermal stability and glass transition temperature remained almost unchanged. This strategy effectively solves the conflict between strength and processing stability in reprocessable epoxy resins, as well as providing a new idea for designing green, high-performance, and closed-loop recyclable epoxy materials.

Polymers doi: 10.3390/polym18101225

Authors: Divan Coetzee Juan Pablo Perez Aguilera Jakub Wiener Jiří Militký

This study presents the development of biocompatible antistatic nanofibrous composite yarns via a scalable AC electrospinning method, incorporating ultrasonicated expanded graphite (uEG) and PEDOT:PSS into polyamide (PA), polyvinyl butyral (PVB), and polyvinyl alcohol (PVA) matrices. TGA confirmed high filler retention during electrospinning. Electrical measurements showed that the addition of uEG and micrographite reduced single-yarn resistance by up to two orders of magnitude compared with neat polymers, yielding normalised resistivities as low as ~105–106 Ω·m and conductivities in the 10−7–10−5 S/m range, suitable for antistatic and sensing applications. However, the large filler–fibre size mismatch and highly porous yarn architecture limited the formation of continuous conductive networks, and mechanical tests revealed strength reductions of up to 70–80% at the highest PVB filler loadings. XRD confirmed a reduction in crystallinity with filler addition, PEDOT:PSS enhanced polymer chain nucleation and thus mechanical properties. Cytotoxicity assays demonstrated that uEG, micrographite, and PEDOT:PSS significantly improved cell viability compared with non-crosslinked PVA, with several PVB-based and PVA/uEG composites showing viability statistically comparable to the DMEM control (>70%) while remaining significantly higher than the Triton positive control. Overall, this work establishes an AC-electrospun route to antistatic nanofibrous yarns that combine high filler retention with enhanced biocompatibility.

Polymers doi: 10.3390/polym18101224

Authors: Vyas Jigar Raytthatha Nensi Vyas Puja Bhupendra Prajapati Pattaraporn Panraksa Sudarshan Singh Chuda Chittasupho

Poor vascularization is one of the basic obstacles to the regeneration of functioning tissues because an oxygen diffusion process and elimination of wastes are essential in preserving the grafts. Recently, biomaterials have allowed the invention of bioinspired polymer scaffolds and replicated the natural extracellular matrix (ECM) due to the mechanical tunability of the synthetic polymers with the biological signals of natural macromolecules. The review uses a mechanistic analysis of the strategies to improve angiogenesis by using surface topography modification, bioactive peptide incorporation and pre-vascularization. Another way to achieve complex, perfusable topologies is by using more sophisticated methods of fabrication, such as electrospinning, 3D/4D bioprinting, or microfluidics. Based on in vitro and in vivo results, we determine angiogenic effectiveness by using cellular assays and animal transfers, pointing towards the translational advances in patents and clinical uses of bone, cardiac, nervous, and skin tissues. In spite of the substantial improvements, large-scale production and high demands of the regulations still exist. The future directions include the incorporation of bioinspired designs and intelligent materials, nanotechnology, and AI-based optimization into developing patient-specific and adaptive scaffolds. The following innovations herald the advent of highly effective constructs that can be used to regenerate tissue and overcome the limitations of present tissue engineering therapies through the introduction of highly effective, vascularized constructs.

Polymers doi: 10.3390/polym18101223

Authors: Carmen Mª. Granados-Carrera Francisco José Calero Castro Victor M. Perez-Puyana Mercedes Jiménez-Rosado Jaime Navarrete-Damián Fernando de la Portilla de Juan Alberto Romero

The development of biomimetic and mechanically functional constructs remains a major challenge in skeletal muscle tissue engineering. In this study, we present a multi-component 3D bioprinted platform integrating a polycaprolactone (PCL) support for mechanical stimulation, a sacrificial gelatin (GE) matrix for controlled bioink deposition, and collagen-based bioinks laden with Rattus norvegicus L6 skeletal muscle cells. The influence of PCL architecture, GE concentration (0.75, 1.5 and 3 wt%), and bioink composition—collagen (C), collagen–Matrigel (CM), and extracellular matrix-based (ECM)—was systematically evaluated. Rheological characterization demonstrated that all bioinks exhibited shear-thinning behavior and suitable viscoelastic properties for extrusion-based bioprinting, with sufficient mechanical stability to withstand dynamic bioreactor conditions. Microstructural analysis revealed highly interconnected porous networks, particularly in ECM-based scaffolds. While no statistically significant differences were observed, the ECM-based bioinks showed the highest cell viability and improved structural organization. Overall, this work demonstrates a versatile bioprinting strategy that combines mechanical support and biomimetic environments, highlighting the potential of ECM-based bioinks for the fabrication of functional skeletal muscle constructs.

Polymers doi: 10.3390/polym18101222

Authors: Mehmet Uğur Yılmazoğlu Bilge Aksu Alcan

This study investigates the mechanical behavior and durability performance of kaolin clay stabilized using a hybrid system composed of Xanthan Gum biopolymer, polypropylene fibers, and Trivoltherm waste fibers. Experimental studies were designed according to the Taguchi L16 orthogonal array to evaluate the effects of different additive combinations. Unconfined compressive strength tests were performed after curing periods of 7, 28, and 90 days, while durability behavior was assessed through 5 and 10 freeze–thaw cycles. In addition, scanning electron microscopy analyses were conducted to investigate the microstructural characteristics of the stabilized soils. The results indicated that strength increased significantly with curing time, reaching a maximum value of 1186 kPa after 90 days. Statistical analyses showed that Xanthan Gum was the dominant parameter affecting strength development, contributing approximately 57–63% to the unconfined compressive strength behavior. Fiber additives also improved ductility, crack resistance, and freeze–thaw durability through reinforcement and crack-bridging mechanisms. The best-performing mixtures exhibited markedly lower strength losses under freeze–thaw conditions compared with untreated soil specimens. Analysis of variance results confirmed that the investigated parameters were statistically significant (p < 0.05), and the developed models showed high prediction accuracy (R2 > 85%). Overall, the findings demonstrate that the synergistic interaction between the biopolymer matrix and fiber reinforcement system provides an effective and sustainable hybrid stabilization approach for improving the engineering performance of clay soils.

Polymers doi: 10.3390/polym18101221

Authors: Jeferson Grisales Katiuska Huapaya Gabriela Silva-Zamora Luis A. Cisternas Paris Lavin David Jeison Manuel Zapata Mariella Rivas

Nitzschia sp., a diatom isolated from Paposo (Antofagasta, northern Chile), was evaluated as a biological solution for removing kaolinite-type clay minerals from recycled process water in large-scale copper mining. Optimization of culture conditions to maximize extracellular polymeric substance (EPS) production revealed that supplementing with 0.1 gL−1 of glucose yielded the highest EPS levels on day 17, reaching 1285 ± 58.9 mgL−1 (control equal to 237.8 ± 34 mgL−1 on day 17). However, maximum dry weight biomass productivity was achieved in the presence of sodium carbonate at a concentration of 1 gL−1 (319 ± 12.5 mgL−1d−1), significantly exceeding the productivity of the control group (242.7 ± 5.4 mgL−1d−1). Notably, low glucose supplementation enhanced EPS synthesis. Application of control-derived EPS of 1 gL−1 rapidly decreased kaolinite initial turbidity from ~2024 FNU to ~354 ± 0.74 FNU within one minute. Even more glucose-derived EPS (1 gL−1) further reduced turbidity to ~22.2 ± 0.1 FNU at 5 min, achieving a flocculation efficiency of ~98.9% after 15 min. Genomic analysis and KEGG annotation identified abundant genes for EPS and carbohydrate metabolism, including numerous glycosyltransferases, glycoside hydrolases, and multiple copies of UDP-glucose 4-epimerase, consistent with strong polysaccharide-biosynthesis capacity. Physicochemical characterization (particle sizing, HPLC, SEM, zeta-potential and FT-IR) showed EPS comprised mainly of rhamnose, fucose, arabinose, xylose and glucose, featuring functional groups (–OH, C=O/COO–, O-acetyl, uronic/guluronic signatures) that interact with kaolinite to promote aggregation. These findings demonstrate that Nitzschia-derived EPS, especially from glucose-supplemented cultures, represent promising sustainable bioflocculants for treating kaolinite-contaminated recycled water in mining operations.

Polymers doi: 10.3390/polym18101220

Authors: Sachin Kumar Sharma Reshab Pradhan Lokesh Kumar Sharma Yogesh Sharma Yatendra Pal Drago Bračun Damjan Klobčar

Carbon/polymer composites are increasingly designed as microstructure-engineered multifunctional materials that combine mechanical reinforcement with electrical/thermal transport, electromagnetic interference (EMI) shielding, and sensing. Performance is governed less by filler fraction than by the coupled control of network topology, junction resistance, and interfacial thermal boundary resistance under processing-induced shear and thermal histories. Electrical response follows percolation combined with tunneling/contact-controlled junctions, producing nonlinear σ(φ) behavior and high piezoresistive sensitivity near the percolation threshold. In contrast, thermal transport is commonly limited by Kapitza resistance and filler–filler junction resistance, restricting exploitation of the intrinsic conductivity of CNTs and graphene. Recent advances emphasize hybrid and 3D carbon architectures that densify connectivity, reduce junction losses, and enable programmable anisotropy via scalable routes such as masterbatch extrusion and additive manufacturing. However, translation remains constrained by dispersion-driven variability, transport–toughness trade-offs, and incomplete durability assessment under cycling, humidity, and reprocessing. This review consolidates mechanistic structure–processing–property relationships and provides application-driven design rules for sensors, EMI shielding, and thermal management.

Polymers doi: 10.3390/polym18101216

Authors: Eulina Fernandes Damião Diego Palmiro Ramirez Ascheri Itamar Rosa Teixeira Roberta Signini Rejane Dias Pereira Mota José Luis Ramírez Ascheri

The increasing demand for sustainable agricultural inputs has driven interest in biodegradable polymers from agro-industrial residues. Pineapple crown biomass (PCB), a widely available lignocellulosic waste, represents a promising feedstock for producing carboxymethylcellulose (CMC). However, the optimal pulping and bleaching conditions for CMC synthesis from this residue remain underexplored. Nevertheless, the combination of CMC derived from PCB with Bacillus subtilis as a seed coating agent for the bean cultivar has not yet been investigated. Here, we produced cellulosic pulps from PCB using a bioreactor, varying NaOH concentration (1–3%), pulping time (1.5–2.5 h), bleaching volume (55–75 mL) and time (60–120 min). The selected pulping condition (2% NaOH, 1.5 h) yielded pulp with high purity (83.9%) and crystallinity (76.35%). After bleaching (65 mL, 90 min), the material was suitable for CMC synthesis under two conditions: CMC1 and CMC2. CMC2 showed a higher degree of substitution (1.010) than CMC1 (0.620) but led to reduced seed germination (77.67%) due to excessive water retention and fungal growth. In contrast, CMC1, with or without B. subtilis, maintained high germination (91%) and significantly increased seedling length (21.30 cm). We conclude that PCB is a viable feedstock for CMC production, and CMC1 exhibits strong potential as an effective seed coating agent for sustainable agriculture.

Polymers doi: 10.3390/polym18101219

Authors: Jana Marx Christian Margreiter Verena Hettich Christina Urban Andreas Otto Wagner Eva Maria Prem Tung Pham Martin Spruck Jan Back

Antimicrobial resistance genes threaten the effective treatment of infectious diseases, underscoring the importance of their control in line with the EU One Health policy. Wastewater treatment plants are recognized hotspots for antimicrobial resistance. We assessed whether multi-channel mixed-matrix membranes (MCMMMs)—polyethersulfone (PES)/polyvinylpyrrolidone (PVP) ultrafiltration membranes with embedded activated carbon—can concurrently reduce microorganisms and extracellular DNA in wastewater effluent, building on prior reports of micropollutant removal. We evaluated the performance of MCMMMs in removing Escherichia coli and Saccharomyces cerevisiae as model organisms, as well as colony-forming units (CFUs) from wastewater effluent at a transmembrane pressure of 1 bar with a filtration area of 66 cm2 over 1 h. DNA was extracted from wastewater effluent following filtration and analyzed to assess changes in microbial community composition. MCMMMs achieved log10 reductions of 5.47 ± 0.42 (Escherichia coli), 5.99 ± 0.46 (Saccharomyces cerevisiae), and 2.79 ± 0.31 (wastewater CFU); reductions by pure PES/PVP membranes were comparable: higher for Escherichia coli and wastewater CFUs, lower for Saccharomyces cerevisiae. Amplicon sequencing showed altered relative abundances in wastewater effluent. Collectively, these findings demonstrate the potential of MCMMMs to simultaneously remove microorganisms, extracellular DNA, and micropollutants, highlighting their suitability for water treatment applications within the One Health framework.

Polymers doi: 10.3390/polym18101218

Authors: Shimaa Ibrahim Moez A. Ibrahim Dina M. Atwa Rageh K. Hussein Hesham Abdulla

Synthetic polymers are widely used in stone conservation, yet their long-term biological stability remains insufficiently evaluated. This study investigates the microbial susceptibility of three commonly used acrylic consolidants, Paraloid B-72, B-66, and B-44, applied to deteriorated limestone. Bacteria, fungi, and actinomycetes were isolated from a deteriorated limestone false door and screened for acid production. From each microbial group, only the strong acid-producing isolates were selected for further investigation, including evaluation of their ability to utilize the three Paraloid resins as sole carbon sources and their deterioration potential on limestone cubes before and after consolidation. Deterioration was assessed by weight loss, compressive strength testing, stereomicroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). All selected strong acid-producing isolates demonstrated the ability to grow on the tested polymers, confirming their biodegradation potential. Mixed microbial cultures caused greater weight loss and compressive strength reduction than single isolates, attributed to synergistic metabolic interactions. Among the consolidants, Paraloid B-72 showed the highest susceptibility to microbial attack, while Paraloid B-66 exhibited comparatively greater resistance, attributed to the steric hindrance of its isobutyl side groups and higher surface hydrophobicity. FTIR and XRD analyses confirmed ester bond hydrolysis, progressive gypsum formation, and structural alteration of the limestone substrate. These findings demonstrate that acrylic consolidants commonly used in stone conservation are not biologically inert and may actively contribute to biodeterioration under microbial colonization, highlighting the need for developing bio-resistant conservation materials.

Polymers doi: 10.3390/polym18101217

Authors: Bircan Arslannur Muhammed A. Ozdemir Ferit Cakir

Pavement repair has become an increasingly time-critical operation as traffic volumes grow and lane-closure windows shrink. This has driven demand for materials that gain full structural strength quickly, reopen to traffic within hours, and hold up longer than conventional patches. This study evaluates polymer concrete (PC), a thermosetting resin-bound aggregate system, through combined laboratory characterization and three-dimensional finite element analysis. Compressive strength, splitting tensile strength, unit weight, and apparent porosity were measured at 1, 3, 7, and 28 days of curing. PC reached 85.97 MPa in compression and 7.63 MPa in tension by day three, with near-zero porosity (0.15%) maintained throughout. These three-day values were used directly as material inputs in the three-dimensional finite element analysis (FEA), reflecting the early traffic reopening scenario that defines rapid repair practice. Structural performance was assessed through 36 static analyses in ANSYS 2024 R2, covering flexible (Hot Mix Asphalt, HMA) and rigid (Jointed Plain Concrete Pavement, JPCP) pavement types, three patch sizes (250 × 250 mm, 500 × 500 mm, and 1000 × 1000 mm), and nine load scenarios per configuration. Safety factors (SF) against internal cracking, interfacial debonding, and compressive failure were computed for both PC and traditional patches. PC consistently outperformed HMA and Portland cement concrete patches across all metrics. On rigid pavements, interfacial safety factors exceeded 22.0, confirming that standard surface preparation is sufficient. On flexible pavements, adopting 0.78 MPa as a conservative lower-bound estimate of PC-HMA interfacial bond strength, five scenarios exhibit debonding risk (250-C, 500-C, 500-D, 1000-C, and 1000-D; SF = 0.47–0.99), while the remaining four show high interfacial risk (SF = 1.11–1.30); primer application and mechanical scarification are required for all PC repairs on flexible pavements regardless of patch geometry. Taken together, the experimental and numerical evidence positions PC as a credible, high-performance option for highway repair.

Polymers doi: 10.3390/polym18101215

Authors: Anna Sowińska-Baranowska Marcin Masłowski Justyna Miedzianowska-Masłowska Magdalena Maciejewska Dainius Martuzevičius Tadas Prasauksas Goda Masione

This study investigates the mechanical, structural, and thermal performance of bio-based composite laminates reinforced with nonwoven fibrous materials derived from polylactic acid (PLA), poly(butylene succinate) (PBS), and polyamide 1010 (PA1010). The fibrous reinforcements, produced using melt-blown and electrospinning techniques, were characterized in terms of morphology, fibre diameter distribution, and wettability, and subsequently incorporated into bio-resin laminates to strengthen them. The curing behaviour of the composites was evaluated using differential scanning calorimetry (DSC). The results demonstrate that fibre structure and morphology strongly influence resin impregnation and interfacial interactions. Mechanical properties varied significantly depending on the reinforcement type. PA1010-based laminates exhibited the highest strength and stiffness due to their compact and uniform fibrous structure. PBS-based systems showed intermediate behaviour, while PLA-based composites displayed lower strength but higher deformability. DSC results indicated that fibre type affected crosslinking efficiency. Thermogravimetric analysis (TGA) revealed similar initial thermal stability of laminates (T5% ≈ 299–313 °C), governed by the resin matrix, while differences at higher temperatures reflected the type of reinforcement used. These findings highlight the importance of fibre morphology and interfacial compatibility in designing sustainable composite laminates reinforced with recycled fibrous materials.

Polymers doi: 10.3390/polym18101214

Authors: Bin Li Huashu Li Zhuo Chen Hongfan Hu Yi Zhou Guoliang Mao Shixuan Xin

Ziegler-Natta (Z-N) catalysts for propylene polymerization were prepared in situ using dibutyl phthalate (DNBP) or 9,9-bis(methoxymethyl)fluorene (BMMF) as internal electron donors (IDs) by treating the support precursors (Mg(OEt)2 or MgCl2·2.5EtOH) or MgCl2 complex solutions with TiCl4 respectively. In this study, eight Z-N catalysts containing two types of IDs were prepared via different preparation routes and systematically characterized with modern analytical techniques. The results indicated that, even with the same IDs, the catalysts prepared by different methods exhibited significant differences in chemical composition, particle size distribution, catalytic activity and stereoselectivity. The properties of polypropylene (PP) were largely influenced by the preparation route of the catalysts. Particularly, the catalysts obtained by the reprecipitation method showed the highest catalytic activity and the smallest MgCl2 particle size. The distribution of stereoselective active centers in the catalysts was simultaneously affected by the preparation method and the type of IDs. In addition, the melting point (Tm) of PP could be used as an effective indicator to evaluate the relative content of the highly isotactic active centers in the catalysts. This study provides valuable insights into the rational design of Z-N catalysts for propylene polymerization, highlighting the critical role of the preparation methodology in tailoring the catalyst properties and active center distribution.

Polymers doi: 10.3390/polym18101213

Authors: Seyyed Kaveh Hedayati Hossein Safari Mozajin Kristoffer Almdal Hans Nørgaard Hansen Aminul Islam

Volumetric additive manufacturing (VAM) is a rapid, layerless photopolymerization process that fabricates three-dimensional (3D) objects by accumulating a projected light dose within a rotating resin vial. Since VAM relies on a polymerization threshold, small changes in resin chemistry, optical attenuation, or inhibition behavior may affect print fidelity and mechanical performance. However, the influence of resin storage history on VAM process stability remains insufficiently understood. This study investigates the chemical, optical, rheological, dimensional, and mechanical evolution of a representative acrylate-based VAM resin subjected to accelerated thermal aging. Resin samples were stored at 50 °C for 6, 12, and 48 days and compared with a non-aged resin. The aged resins were characterized, and the mechanical performance of printed and cast specimens was tested. The results indicate that storage did not cause any observable changes in molecular weight, and viscosity variations remained limited. However, aging produced measurable changes in optical, dimensional, and mechanical properties. The printed cylinder diameter increased from 12.9 mm for the non-aged resin to 14.4 mm after 48 days of aging. The tensile strength of printed samples peaked after 12 days of aging, and the compressive modulus increased with prolonged aging. Resin aging should be treated as an explicit manufacturing input, and routine resin monitoring and exposure recalibration are recommended to improve VAM reproducibility.

Polymers doi: 10.3390/polym18101212

Authors: Quang Hung Nguyen Tien Thanh Nguyen Zaki S. Saldi Arief S. Budiman Christian Harito Monica Dwi Hartanti Avinash Baji Vi Khanh Truong

In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films embedded with silver nanoparticles were fabricated to investigate their antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Inspired by the nanoscale topographies of natural antibacterial surfaces, such as dragonfly and cicada wings, microstructured pillars were introduced onto the polymer surface to enhance its bactericidal activity by increasing the effective contact area. Surface morphology was characterised using scanning electron microscopy (SEM), including higher-magnification imaging of micropillar surfaces, while energy-dispersive X-ray spectroscopy confirmed the presence of silver. Higher-magnification SEM revealed nanoscale surface features on the micropillars, attributed to embedded or surface-associated silver nanoparticles. Antibacterial performance was evaluated using confocal laser scanning microscopy with live/dead staining. The PVDF-HFP/Ag films exhibited a significant reduction in bacterial viability, particularly against S. aureus (reducing viability to 0.6% ± 1.1%), while showing moderate activity against E. coli (41.0% ± 3.7% viability). While the fabricated micropillars (~5 µm) are larger than bacterial cells and unlikely to induce direct mechanical rupture, they increase surface interaction. To further investigate the theoretical antibacterial mechanism of scaled-down features, finite element analysis (FEA) was performed to model the mechanical interaction between bacterial cells and nanostructured pillars. The simulation results indicated localised stress concentrations that could compromise bacterial membrane integrity, suggesting a possible mechanobactericidal contribution if the microstructures are further reduced to the nanoscale, in addition to the primary biochemical effects of silver nanoparticles. FEA results do not aim to explain the experimentally observed antibacterial performance and should be interpreted only as a conceptual investigation. These findings demonstrate the potential of bio-inspired PVDF-HFP/Ag films as antibacterial materials for food packaging and related applications, subject to future comprehensive toxicity and quantitative microbiological evaluations.

Polymers doi: 10.3390/polym18101211

Authors: Rittin Abraham Kurien Gokul Kannan Wantanwa Krongrawa Supakij Suttiruengwong Pornsak Sriamornsak

Polyvinyl alcohol (PVA) and hydroxypropyl methylcellulose (HPMC) films plasticized with glycerin or polyethylene glycol (PEG) were investigated to elucidate structure–property relationships in hydrophilic polymeric film systems. Films were prepared by solution casting at a fixed polymer concentration of 2.7% w/w with plasticizer contents ranging from 0.49 to 1.33% w/w, yielding continuous, free-standing films with good surface integrity. Polymer type and plasticizer dosage strongly affected film breakdown behavior. HPMC films with high plasticization swelled and disintegrated. Effective plasticization was shown by a steady drop in tensile strength and elastic modulus and a significant rise in elongation at break. PVA films plasticized better than HPMC films in PEG-containing solutions. Fourier transform infrared spectroscopy verified hydrogen bonding-driven polymer–plasticizer interactions, with glycerin outperforming PEG. Increasing plasticizer percentage reduced crystallographic order and thermal transition temperature in X-ray diffraction and differential scanning calorimetry. Scanning electron microscopy indicated smooth and uniform surfaces at intermediate plasticizer levels, but variability at higher loadings. Among the studied formulations, PVA films containing 1.33% w/w plasticizer and HPMC films containing 1.05% w/w plasticizer provided the most balanced combination. These findings support physiochemically rational PVA and HPMC film design for pharmaceutical applications.

Polymers doi: 10.3390/polym18101210

Authors: Pedro F. Mayuet Ares Lucía Rodríguez-Parada Sergio de la Rosa Moises Batista

Additive manufacturing by Fused Filament Fabrication (FFF) enables the fabrication of complex polymer components, although limitations in surface quality and dimensional accuracy often require post-processing. Abrasive water jet machining (AWJM) is a non-thermal technique suitable for improving surface integrity in polymers and composites without inducing thermal damage. This study investigates the AWJM performance on FFF-printed polylactic acid (PLA) and carbon-fiber-reinforced PLA (PLA–CF), focusing on the influence of water pressure (WP), traverse feed rate (TFR), and abrasive mass flow rate (AMFR). A full factorial design was implemented, and surface integrity was evaluated through surface roughness (Ra) and kerf taper (T), considering their variation across characteristic cutting regions: initial damage region (IDR), smooth cutting region (SCR), and rough cutting region (RCR). Results show that WP and TFR are the dominant parameters, while AMFR has a limited effect within the studied range. The SCR exhibits the lowest roughness, whereas the RCR shows significant degradation due to energy loss. Both materials present similar behavior, with only minor improvements in PLA–CF. ANOVA confirms that process parameters have a stronger influence than material type, providing useful criteria for AWJM optimization in FFF polymers.

Polymers doi: 10.3390/polym18101208

Authors: Mohammad Anwar Parvez

Polymer-based product use is rapidly increasing worldwide, resulting in critical social, environmental, ecological, economic, and health effects. Worldwide efforts have increasingly focused on solutions to the equilibrium consumption, production, and disposal of plastics to tackle these issues. The frontiers of biodegradable and bio-based polymers are continually advancing in pursuit of sustainability. Therefore, designing ecological bioplastics made of both biodegradable and bio-based polymers reveals chances to overcome plastic pollution and resource depletion. Polymeric materials are mainly used to manufacture different products at the beginning of their lifespans and which become waste after usage. Numerous sustainability strategies and polymer recycling methods are described and mostly classified into chemical, mechanical, and thermal recycling processes. This manuscript presents a New Polymers Frontier in Recycling and Sustainability Using an Ensemble of Deep Learning with a Heuristic Search Algorithm (NPFRS-EDLHSA). This work is devoted to computational polymer typology, which is based on machine learning algorithms applied to data on physicochemical properties. Although polymer classification can facilitate downstream materials research, the present study does not directly simulate recycling, environmental impacts, or sustainability. The main contributions made by this work include (i) an exploratory analysis of ensemble deep learning models to classify polymers by type on a small and unbalanced dataset; (ii) an evaluation of the effect of feature selection with a heuristic optimization methodology; and (iii) a comparison of the effects on classification performance under limited data conditions. This research sets out to provide a methodological explanation, not arguments for industrial-scale applicability. For the polymer-type classification process, the proposed NPFRS-EDLHSA model designs an ensemble of deep learning techniques, namely a bidirectional recurrent neural network (BiRNN) model, a bidirectional gated recurrent unit (BiGRU) method, and a graph autoencoder (GAE) technique. Finally, the grasshopper optimization algorithm (GOA) adjusts the hyperparameter values of the ensemble models optimally and results in an improved classification performance. A wide-ranging set of experiments was conducted to validate the performance of the NPFRS-EDLHSA method. The experimental results indicated that the NPFRS-EDLHSA technique achieved a better performance than an existing model.

Polymers doi: 10.3390/polym18101209

Authors: Kyu Oh Kim

Glucose-responsive smart insulin delivery systems that mimic the pancreatic insulin release system can improve the health and quality of life of patients with diabetes. In this study, a spherical drug delivery carrier encapsulating insulin was developed to achieve improved glucose accessibility and a rapid pH response using polyhedral oligomeric silsesquioxane (POSS) as a sterically stabilizing structure. Highly sensitive poly(acrylic acid) (PAA)-POSS-aminophenylboronic acid (APBA)@insulin (386 ± 69 nm), a spherical drug delivery carrier encapsulating insulin, was synthesized using POSS, a hydrophobic material, and PAA and APBA, which respond to pH and glucose, respectively. The drug carrier has dual reactivity with pH and glucose, and the synthesis of the carrier was confirmed through Fourier transform infrared (FT-IR) spectroscopy, which verified that the particles were stable at each pH through the zeta-potential data. In particular, PAA-POSS-APBA@insulin exhibited highly sensitive drug delivery characteristics, in which the backbone of PAA was expanded under acidic conditions (around pH 5.0) and insulin bound to the boronic acid inside could rapidly and selectively react with trace amounts of glucose. PAA-POSS-APBA@insulin nanoparticles exhibited no HeLa cell cytotoxicity up to a high concentration of 640 μg/mL, and the cell growth rate increased with the concentration, indicating biocompatibility. The average blood glucose level of diabetic mice treated with POSS-APBA@insulin (4.0 IU/kg) decreased for >6 h and remained stable. Thus, PAA-POSS-APBA@insulin can function as a stimulatory-responsive drug carrier targeting hyperglycemic environments.

Polymers doi: 10.3390/polym18101207

Authors: Selin Kyuchyuk Dilyana Paneva Milena Ignatova Nevena Manolova Iliya Rashkov Daniela Karashanova Milena Mourdjeva Nadya Markova

In this study, a hierarchical design strategy is introduced for tuning the release of rosmarinic acid (RA) from electrospun poly(L-lactide) (PLA) fibrous materials via surface engineering with chitosan/hyaluronic acid (Ch/HA) polyelectrolyte complexes (PECs). RA was selectively incorporated within the fiber bulk, the PEC coating, or both, enabling control over its spatial distribution. The PEC coating, formed by sequential dip coating, was shown to act as a diffusion-regulating layer with a dual role—either retarding RA release or promoting rapid initial release when functioning as a surface-associated reservoir. As a result, the release kinetics could be systematically tuned depending on the coating architecture and RA localization. Thorough characterization confirmed successful coating formation, enhanced surface hydrophilicity, and improved mechanical performance. All RA-loaded materials retained high antioxidant activity and exhibited pronounced antibacterial and antifungal effects against Staphylococcus aureus, Escherichia coli, and Candida albicans. This work introduces PEC-modified electrospun systems as a versatile platform for the rational design of multifunctional fibrous biomaterials with controlled release profiles, with potential applications in wound healing and drug delivery.

Polymers doi: 10.3390/polym18101206

Authors: Jasmina Jusic Alessandra Filieri Silvia Crognale Matteo Manni Swati Tamantini Vittorio Vinciguerra Alessandro Cardarelli Marco Barbanera Dennis Jones Dominik Matt Manuela Romagnoli

The valorisation of lignocellulosic residues into bio-based feedstocks is a key strategy for advancing circular bioeconomy models. In this study, chestnut wood residues, including virgin wood (VW) and detannized wood (DT) from the tannin industry, were evaluated as substrates for polyhydroxyalkanoate (PHA) production using Cupriavidus necator. Biomass was subjected to thermo-acid hydrolysis followed by ion-exchange detoxification, yielding hydrolysates rich in organic acids (levulinic, acetic, and formic acids) and residual inhibitory compounds. Both substrates supported microbial growth and PHA accumulation, although clear differences in performance were observed. The maximum biomass concentration reached 1.26 ± 0.01 g L−1 in VW hydrolysate and 0.40 ± 0.03 g L−1 in DT hydrolysate. PHA production was higher in VW hydrolysate, reaching 68.51 mg L−1 with 5.44% (w/w) accumulation, while DT hydrolysate yielded 0.21 mg L−1 with 6.01% (w/w). The reduced biomass formation in DT hydrolysate was associated with the greater persistence of inhibitory compounds generated during thermo-acid treatment. Although the obtained PHA yields are lower than those reported for optimized lignocellulosic systems, this study demonstrates for the first time the feasibility of producing PHA from chestnut wood residues, including industrial detannized byproducts, without nutrient supplementation. These findings highlight the potential of tannin-industry waste streams as alternative feedstocks for biopolymer production, while indicating that optimization of hydrolysis conditions, detoxification efficiency, and fermentation strategy is required to improve process performance.

Polymers doi: 10.3390/polym18101205

Authors: Guigang Shi Yuhui Li Wenlong Li Ruoying Zhu Ying Sun

The durable enzyme functionalisation of cellulosic fibres is often limited by enzyme deactivation under alkaline processing and insufficient wash resistance. Here, a cold pad–batch (CPB)-compatible route integrates reactive dyeing and lysozyme anchoring by using the commercial bifunctional dye C.I. Reactive Red 195 (MCT/VS) as an interfacial mediator to build a cellulose–dye–lysozyme ternary layer. The dye is first fixed on cotton, and residual electrophilic motifs are proposed to facilitate subsequent coupling with nucleophilic residues in lysozyme. A nine-run, four-factor/three-level orthogonal design was used to identify a practical processing window; under the selected condition, an ELISA-equivalent releasable lysozyme level of 53.8 U/L was achieved together with moderate colour strength (K/S = 6.5). The treated fabrics exhibited 96.5% inhibition against Escherichia coli and >99.9% against Staphylococcus aureus and retained antibacterial functionality after five ISO 105-C06 laundering cycles. Textile-relevant properties were preserved, including colour fastness (Grade 4–5), tensile strength retention (~86%), and capillary wicking close to pristine cotton. This dye-mediated strategy offers a practical route to wash-resistant bioactive interfaces on cellulose fibres and is extendable to regenerated cellulose and wood-pulp-derived cellulosics.

Polymers doi: 10.3390/polym18101204

Authors: Osung Kwon Byungrak Son

Proton exchange membranes (PEMs) are essential for PEM fuel cells, with proton conductivity arising from the hydration-induced ionic channel network. PEM performance can be enhanced through pretreatments, such as annealing, which reconstruct the ionic channels. This study investigates the ionic channel network variation in Nafion 212 under continuous annealing at 90 °C using current-sensing atomic force microscopy (CSAFM). A nanoscale PEM fuel cell was formed with a Pt-coated CSAFM tip and Pt-coated Nafion surface. Topography and surface roughness analyses revealed geometrical changes from annealing. Current-sensing images and histograms qualitatively assessed local conductance and ionic channel distribution. The ionic channel network density was quantitatively evaluated using the number of protons moving through the ionic channel network (NPMI), derived from CSAFM and electrodynamics principles. NPMI directly reflects ionic channel density. From the unannealed state to 60 h, NPMI increased linearly at 1 × 104 h−1, indicating enhanced channel formation. Beyond 60 h, NPMI decreased linearly at 1.9 × 105 h−1, reflecting progressive network degradation. As the ionic channel network increases, the number of protons reaching the membrane surface also increases, whereas in the opposite case it decreases. Thus, NPMI becomes evaluation criterion for ionic channel network density. These findings systematically link nanoscale structural changes to ionic channel reconstruction and proton transport in Nafion 212, providing insight into PEM performance evolution under thermal treatment.

Polymers doi: 10.3390/polym18101203

Authors: Xiaodi Wang Wenjie Wang Rongfeng Li Kun Gao Ronge Xing Xuexin Zhang Gaoli Zhou Lijing Yin Junhao Chen Hang Li Guantian Li

The marine benthic invertebrate Urechis unicinctus exhibits extraordinary tolerance to hypoxic environments, making its coelomic fluid a unique and promising biological source for discovering novel stress-adapting macromolecules. Polysaccharides derived from the coelomic fluid of U. unicinctus were systematically extracted, fractionated, and characterized to investigate their structural features and associated biological activities. Gradient ethanol precipitation (30–80%) combined with DEAE-52 ion exchange chromatography yielded twelve fractions with distinct physicochemical properties. Significant variations were observed in molecular weight (103–105 Da), sulfate content (3.77–24.26%), and monosaccharide composition. High-ethanol fractions, particularly U68P and U18P (extracted at 60 °C and 100 °C, respectively, and both precipitated with 80% ethanol), were enriched in low-molecular-weight, highly sulfated heteropolysaccharides composed of galactose, fucose, glucosamine, and ribose. These fractions exhibited superior antioxidant activities, including strong scavenging effects against DPPH, ABTS, and hydroxyl radicals. Moreover, they demonstrated pronounced neuroprotective effects in the oxygen–glucose deprivation/reoxygenation (OGD/R) model using SH-SY5Y cells, significantly improving cell viability. Structure–activity relationship analysis revealed that reduced molecular weight, increased sulfation degree, and more diverse monosaccharide composition (e.g., more diverse monosaccharide composition) synergistically contribute to improved bioactivity by facilitating cellular uptake and exposing functional groups. In contrast, high-molecular-weight homoglucan fractions showed relatively weak effects. Overall, this study identifies U. unicinctus coelomic fluid as a promising source of bioactive polysaccharides and provides a theoretical basis for the development of marine-derived anti-hypoxic and antioxidant agents.

Polymers doi: 10.3390/polym18101202

Authors: Liangcong Fan Peisen Xu Hongyu Wang Zhifeng Cai Juan Zuo Cong Liu Xiaohang Tan Fengxiong Long Hao Luo Qingqing Gao

A novel transition-metal-free alkyne–thiol click polymerization with 100% atom economy is reported. Using tBuOLi as a catalyst at 80 °C, the polymerization efficiently yields poly(vinyl sulfide)s (PVSs) with molecular weights up to 11,800 g/mol and yields up to 91%. These sulfur-rich polymers exhibit high thermal stability (Td up to 293 °C) and high refractive indices (1.8375–1.6383) across the visible range. By integrating abundant sulfur coordination sites with aggregation-induced emission (AIE) properties, the PVS aggregates serve as high-performance fluorescent chemosensors. The sensor enables exclusive, sensitive trace detection of Pd2+ and Au3+ with remarkable anti-interference capability and pH robustness (pH 1–7). Notably, an ultrafast response (1–2 min) for Pd2+ is achieved, with limits of detection (LOD) reaching 7.11 × 10−7 M for Pd2+ and 1.06 × 10−6 M for Au3+, and corresponding limits of quantification (LOQ) reaching 2.37 × 10−6 M and 3.53 × 10−6 M, respectively. This methodology offers a sustainable route to heteroatom-rich macromolecules for next-generation optical engineering and environmental monitoring.

Polymers doi: 10.3390/polym18101201

Authors: Dragos Gabriel Zisopol Mihail Minescu Dragos Valentin Iacob

This paper presents the results of research conducted on the influence of thermoplastic extrusion parameters (layer height per pass—Lh and the percentage fill density—Id) and heat treatment (annealing) on the compressive strength of specimens manufactured by thermoplastic extrusion of virgin and recycled polyethylene terephthalate glycol (PETG and rPETG) filaments. To support the study, using the parameters Lh = (0.10–0.20) mm and Id = (50–100)%, 90 compression test specimens were manufactured from PETG and rPETG (45 specimens for each material), which were subsequently subjected to heat treatment by annealing at a temperature of 75 °C for a period of 180 min. The results obtained highlight a significant correlation between the variable manufacturing parameters (Lh and Id) and the compressive strengths (Cs). The average compressive strengths of the 45 specimens made from PETG are 44.15% lower than the average compressive strengths of the specimens made from rPETG. The annealing heat treatment resulted in a 31.40% decrease in the average compressive strengths of the specimens made from PETG and a 0.63% increase in the average compressive strengths of the specimens made from rPETG. The specimens made from PETG exhibited increased thermal sensitivity, which led to molecular relaxation, while rPETG exhibited superior thermal stability acquired through recycling.

Polymers doi: 10.3390/polym18101200

Authors: Yue Ming Xinhan Qiao Haoran Meng Wentian Zeng Xiaolei Xia Feng Yang Ke Xu Zhijin Zhang Chuanhui Huang

As power equipment insulation materials, epoxy resin and phenolic resin are inevitably exposed to damp-heat environments during long-term operation, leading to ageing degradation. This study systematically investigates the effects of damp-heat ageing (85 °C, 90% RH, 0–56 days) on the flame retardancy of both resins through oxygen index tests, vertical combustion experiments, and microstructural analysis (SEM/EDS). Results indicate that ageing unexpectedly enhances flame retardancy: Epoxy resin: Oxygen index rapidly increased from 64.4% (0 days) to 76.5% (21 days), then stabilised at 75–76%. Afterflame time decreased from 143 s to 109 s after 56 days. Phenolic resin: Oxygen index rose continuously with ageing; afterflame time dropped sharply from 211 s (0 days) to 0 s (56 days). Mechanistic analysis reveals that ageing promotes surface enrichment of flame-retardant elements (Ca, Mg, Si in epoxy; Al, Mg in phenolic) and structural changes (e.g., porous carbonisation), which facilitate barrier effects against heat/oxygen diffusion. This work challenges conventional views on ageing-induced degradation, providing new insights for evaluating insulation safety in humid environments.

Polymers doi: 10.3390/polym18101199

Authors: Dušica Krunić Stevan Armaković Maria M. Savanović Sanja J. Armaković

The increasing emission of harmful gases into the atmosphere represents a major environmental challenge, driving the need for efficient air purification materials. Poly(methyl methacrylate) (PMMA) has emerged as a promising candidate due to its favorable physicochemical properties and adsorption potential. In this study, the interactions between PMMA and selected sulfur-containing pollutants (CH3SH, COS, CS2, H2S, and SO2) were systematically investigated using a multiscale computational approach. Initial structural exploration was performed using extended tight-binding (xTB) methods, followed by refinement at the density functional theory (DFT) level, while molecular dynamics (MD) simulations were employed to capture the dynamic behavior of the systems. The results suggest that all investigated gases exhibit attractive interactions with PMMA, with interaction strength strongly dependent on molecular polarity and electronic structure. Among the studied systems, SO2 shows the strongest binding, while CS2 exhibits the weakest interaction. Energy decomposition based on symmetry-adapted perturbation theory (SAPT) and electronic structure analyses suggest that electrostatic and donor–acceptor interactions play a dominant role for strongly interacting systems, whereas weaker interactions are primarily governed by dispersion forces.

Polymers doi: 10.3390/polym18101198

Authors: Nitesh Subedi Md Monjur Hossain Bhuiyan Alfredo Becerril Corral Omkar Gautam Md Ariful Islam Zahed Siddique

High-pressure hydrogen exposure may induce transport and diffusion–relaxation–controlled changes in elastomeric sealing materials that differ from conventional fluid aging. Hydrogen uptake through solution–diffusion processes can lead to swelling, redistribution of molecular mobility, viscoelastic evolution, and, under certain conditions, cavitation or microvoid formation during decompression, which may affect long-term sealing performance. This review compiles experimental results for commonly used elastomers, including Nitrile Butadiene Rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), Fluoroelastomer (FKM), Ethylene Propylene Diene Monomer (EPDM), and silicone, and summarizes reported ranges of hydrogen diffusivity, solubility, and permeability under high-pressure conditions. These transport characteristics are compared with mechanical and microstructural observations obtained from Dynamic Mechanical Analysis (DMA), Nuclear Magnetic Resonance (NMR), decompression testing, and micro-computed tomography (µXCT) imaging. Available evidence suggests that hydrogen-induced changes are predominantly governed by physical processes, including swelling, plasticization-like mobility changes, and constraint redistribution, while extensive chemical degradation of the polymer backbone is generally limited under clean hydrogen conditions. Materials with similar conventional mechanical properties may, therefore, exhibit different hydrogen uptake, viscoelastic response, and resistance to decompression damage. Conventional single-point mechanical tests, such as tensile measurements, may not fully capture the time-dependent viscoelastic evolution relevant to sealing performance. This work proposes a multiscale characterization framework integrating transport, viscoelastic, molecular, and microstructural analysis for more reliable evaluation of elastomers in hydrogen service, supporting improved qualification strategies for high-pressure hydrogen systems.

Polymers doi: 10.3390/polym18101197

Authors: Johnatan Gabriel Bernal-Carrillo Mariamne Dehonor-Gómez Luis E. Lugo Ana del Carmen Susunaga Notario Víctor Hugo Mercado-Lemus José Antonio Betancourt-Cantera Raúl Pérez-Bustamante John Edison García-Herrera Hugo Arcos-Gutiérrez Isaías E. Garduño

The increase in environmental impacts associated with non-recyclable flexible plastic packaging underscores the need for sustainable alternatives. This work presents a new paper-based laminate containing cellulose, ethylene-vinyl alcohol (EVOH), and an anaerobic degradation additive (ECO-ONE®) to replace existing trilaminate plastics for dry food applications. The hybrid package maintains consistent mechanical performance compared to conventional structures while improving barrier properties: oxygen transmission rate decreased from 35.38 ± 2.1 to 0.56 ± 0.05 cm3/m2/day (0% RH), and water vapor transmission rate decreased from 4.85 to 1.22 g/m2/day. The hybrid structure uses 37% less virgin resin and reduces adhesive/solvent use by 50%. Life cycle assessment indicates a 47% reduction in environmental impact. Approximately 85–90% of waste avoidance is attributable to reduced virgin plastic and adhesive use, with 10–15% attributable to end-of-life treatment. This study presents a practical transitional alternative for dry food packaging applying circular economy principles.

Polymers doi: 10.3390/polym18101196

Authors: Yazeed A. Alsharedah Aly Ahmed Fayyaz Ullah Yasser Altowaijri

The stability of upstream tailings remains a critical geotechnical challenge due to the inherently weak mechanical properties of fine-grained mine tailings. This study investigated a tailing improvement method using (i) emulsified polymer and (ii) combinations of recycled gypsum and cement kiln dust (CKD). A comprehensive experimental program—including unconfined compressive strength (UCS) analysis, direct shear tests (DSTs), and oedometer consolidation tests—was conducted to assess the performance of various treatment mixtures. The results showed that blends of CKD and gypsum, particularly at a 1:2 ratio and a 10% dosage, significantly improved shear strength, reduced compressibility, and lowered hydraulic conductivity by over an order of magnitude. The inclusion of plaster (commercial gypsum) further enhanced the UCS by more than 100% compared to recycled gypsum and increased the cohesion (c’) values from 0 to 32.8–47.2 kPa. The compression index (cc) decreased from 0.15 to 0.05, and the maximum volumetric strain (εv) at an applied effective stress of 800 kPa decreased from 17% to 5%. Emulsified polymer treatments also enhanced the mechanical and hydraulic properties of the clayey tailings; however, the overall improvements were lower than those achieved with CKD–gypsum blends, suggesting that further optimization of the polymer concentration or its combination with mineral additives may yield better results. These findings offer a foundation for further research into the use of polymers in geoenvironmental applications, particularly for erosion control, contaminant encapsulation, and hydraulic barrier development. Overall, this study highlights the potential of using industrial by-products, such as CKD and gypsum, as sustainable, cost-effective materials to improve tailing performance, while identifying promising directions for polymer-based solutions in geotechnical engineering.

Polymers doi: 10.3390/polym18101194

Authors: Rutuja U. Amate Aviraj M. Teli Sonali A. Beknalkar Chan-Wook Jeon

The rational design of electrode architectures is essential for advancing high-performance supercapacitors. In this study, Nd2O3 electrodes with controlled structural features were developed via a polyacrylic acid (PAA)-assisted hydrothermal approach. By systematically tuning PAA concentration, the growth mechanism of Nd2O3 was effectively regulated, leading to a distinct morphological transition from compact agglomerates to well-defined hierarchical structures. The optimized Nd2O3-P2 electrode exhibits a porous and interconnected architecture, providing enhanced electrolyte accessibility and shortened ion diffusion pathways. This structural optimization significantly improves electrochemical performance, delivering a high areal capacitance of 26.889 F/cm2 at 10 mA/cm2, along with excellent rate capability and reduced internal resistance. Kinetic analysis reveals that charge storage is predominantly governed by diffusion-controlled Faradaic processes, with the optimized structure facilitating rapid ion transport and efficient redox activity. Additionally, the electrode demonstrates excellent cycling durability, retaining 87.08% capacitance over 12,000 cycles. An asymmetric supercapacitor assembled using Nd2O3-P2 and activated carbon achieves stable operation up to 1.5 V, delivering good capacitance retention (81.2%) after 7000 cycles. This work highlights the effectiveness of PAA-induced structural tuning and provides a practical strategy for developing advanced rare earth oxide-based electrodes for energy storage applications.

Polymers doi: 10.3390/polym18101195

Authors: Yingjie Wang Bin Wang Peng Huang Yan Wu Fengshan Zhang Zhiqiang Sun Hongxia Ma Wenguang Wei Kefu Chen

The efficient utilization of hardwood lignocellulosic biomass has attracted increasing attention as a sustainable strategy for the high-value conversion of renewable resources. Chemical-mechanical pulping (CMP) is a promising route for hardwood utilization; however, its performance is strongly influenced by species-dependent differences in chemical composition, macromolecular structure, and physical accessibility. In this study, four representative hardwood species (poplar, sycamore, eucalyptus, and acacia) were selected as model feedstocks to investigate the relationships between structural characteristics and CMP performance in alkali-assisted systems. The chemical composition and structural features of cellulose, hemicellulose, lignin, and lignin-carbohydrate complexes were characterized, together with key physical parameters including density, porosity, and fiber morphology. The effects of alkali charge on fiber softening, fibrillation development, and paper properties were then evaluated. The results revealed pronounced species-dependent differences in alkali response, which were closely correlated with variations in cellulose supramolecular organization, hemicellulose substitution characteristics, lignin structural features, lignin-carbohydrate associations, and wood microstructure. This study provides a comprehensive qualitative comparative analysis of the relationships between wood structural features and CMP performance. Hardwoods with lower density and higher porosity exhibited more efficient alkali penetration and superior performance under mild conditions, whereas denser species such as sycamore and eucalyptus required higher alkali charge. This work provides important insights into the structure-performance relationships governing alkali-assisted CMP behavior, and offers useful guidance for the efficient utilization of lignocellulosic biomass in pulp and paper applications.

Polymers doi: 10.3390/polym18101191

Authors: Jair de Jesús Arrieta Baldovino Luis Carlos Suárez López Jesús Alberto Alcalá Vergara Yamid E. Nunez de la Rosa

Research on sustainable alternatives to conventional soil stabilization has promoted the use of natural biopolymers as partial substitutes for cementitious binders. This study presents a mechanical and microstructural comparison between poorly graded Colombian sand stabilized with guar gum (GG) and Type III Portland cement. GG was incorporated at 0.25–1.00% with curing periods of 28 and 90 days, while cement contents ranged from 3 to 9% with 7 days of curing. A total of 108 cylindrical specimens were tested using unconfined compressive strength (UCS) and SEM–EDS analyses. Results show that both binders significantly improve soil strength, although cement exhibits a steeper strength gain due to hydration processes. GG-treated samples reached a maximum UCS of 470 kPa at 90 days, representing an increase of approximately 40% compared to 28 days and showing comparable performance to 5% cement. The porosity/binder index (η/Biv) demonstrated a strong correlation with UCS (R2 > 0.91), confirming its predictive capability. Microstructural analysis revealed the formation of C–S–H and ettringite in cement-treated samples, while GG-treated soils exhibited hydrogel bridges and the presence of pores that may influence particle bonding. Overall, the results demonstrate the technical feasibility of GG as a sustainable soil stabilization alternative.

Polymers doi: 10.3390/polym18101190

Authors: Carmen Olivas Alonso Amparo Chiralt Sergio Torres-Giner

In this study, fully bio-based oligomers of butylene succinate (OBS) with different molecular weights (low: L-OBS, medium: M-OBS and high: H-OBS) were incorporated into poly(butylene succinate) (PBS) by melt mixing at varying loadings of 5–15 wt%. Then, PBS/OBS films were obtained by thermo-compression and characterized to assess their suitability for sustainable food packaging. Thus, OBS were homogeneously incorporated into PBS matrix and modulated the thermal, mechanical, and barrier properties of the PBS. L-OBS (Mn = 1150 g·mol−1) plasticized the amorphous PBS, depending on its concentration, more effectively than M-OBS (Mn: 8700 g·mol−1) and H-OBS (Mn: 18,650 g·mol−1), as deduced from the thermo-mechanical analysis. In every case, OBS enhanced crystallinity, mainly L-OBS, which reduced the film strength and increased water vapor permeability, depending on its concentration. In contrast, H-OBS improved mechanical strength, stiffness, and barrier performance. In all cases, X-ray diffraction confirmed the preservation of the PBS’s monoclinic crystalline structure but slightly shifted the diffraction angle depending on the ratio of the end-chain groups in the blend, thus reflecting the contribution of OBS in the crystalline lattice. Finally, oligomer incorporation resulted in an overall migration increase in different food simulants, impairing their application in packaging.

Polymers doi: 10.3390/polym18101193

Authors: Martin Vasina Katarina Monkova Adrian Vodilka

Noise is an environmental factor that negatively affects the health of living organisms and must therefore be mitigated. One effective approach to noise reduction is the use of passive materials for sound absorption. Moreover, with the increasing use of 3D printing technology, it is now possible to produce complex material structures for noise reduction that cannot be manufactured using conventional manufacturing techniques. This study investigates the sound absorption performance of novel 3D-printed concentric tubular structures made of acrylonitrile styrene acrylate (ASA) with intermediate lattice inserts. The sound absorption properties of these structures were experimentally evaluated in the frequency range of 200–1600 Hz using a two-microphone acoustic impedance tube. Various factors influencing sound absorption properties were investigated, including the number of concentric tubes, sample height, strut diameter, and back air cavity thickness. The experimental results show that the sound absorption performance depends significantly on the design parameters of the proposed system. The average sound absorption coefficient (αavg) increased with the number of concentric tubes and reached a maximum value of 0.264 for the configuration with five tubes. The highest sound absorption peak (αmax = 0.623) was achieved for the structure with two concentric tubes, a strut diameter of 3 mm, a height of 30 mm, and a back air cavity of 10 mm at a frequency of approximately 1548 Hz. Furthermore, increasing the strut diameter and sample height generally improved sound absorption performance, while the presence of a back air cavity significantly shifted the absorption peak toward lower frequencies, thereby enhancing low-frequency sound absorption.

Polymers doi: 10.3390/polym18101192

Authors: Yongxiang Li Chaoyang Guo Shizhong Mi Xuliang Zhang Jinbo Bai Yongjie Jia Hongyin Yu Jing Li

To enhance the overall performance of direct coal liquefaction residue (DCLR)-modified asphalt, particularly its low-temperature cracking resistance, SBS and aromatic oil were employed for composite modification. Nine composite-modified asphalt formulations were prepared based on an orthogonal experimental design. High-and low-temperature rheological properties and microstructure of all modified asphalts were systematically evaluated using a dynamic shear rheometer (DSR), a bending beam rheometer (BBR), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results indicate that composite modification significantly enhanced the high-temperature performance of the asphalt. Modified asphalt labeled as Sample No. 9 (9% DCLR, 4% SBS, and 6% aromatic oil) demonstrated the minimal non-recoverable creep compliance (Jnr) value of 0.58 kPa−1 at 64 °C, indicating a 78.6% decrease relative to the matrix asphalt. In terms of low-temperature performance, Sample No. 3 satisfied the Superpave cracking resistance criterion, exhibiting a creep rate (m-value) of 0.312 at −12 °C. It was revealed by FTIR analysis that the interaction between the composite modifier and the base asphalt was mainly physical blending, and no new functional groups were generated either before or after aging. The improvement in performance was attributed to the physical compatibility and structural reorganization among the components. Microstructural analysis revealed that the uniform dispersion of modifiers in matrix asphalt and the subsequent formation of a dense micelle structure after aging contributed to the enhanced macroscopic performance. This study provides theoretical and technical support for the high-value application of DCLR in asphalt pavements.

Polymers doi: 10.3390/polym18101189

Authors: M. Ramesh M. Tamil Selvan L. Rajeshkumar P. Ramya

Our investigation into Hibiscus rosa-sinensis fibers (HRFs) for composite applications involved a multi-step process, primarily fiber extraction through water retting and subsequent surface modification by using sodium hydroxide (NaOH) and trimethoxy methyl silane (TMMS). Through the compression molding technique, untreated HRF-reinforced poly-lactic acid (PLA) composites (UHRFCs), NaOH-treated HRF-reinforced PLA composites (NHRFCs), and TMMS-treated HRF-reinforced PLA composites (THRFCs) were fabricated. The experiments were conducted, and the findings revealed a substantial increase in properties of both NHRFCs and THRFCs compared to UHRFCs. Notably, these enhancements encompassed tensile strength (13.66% and 19.39%), tensile modulus (13.41% and 20.70%), flexural strength (15.98% and 23.17%), flexural modulus (17.13% and 26.58%), impact strength (15.62% and 33.07%), Shore-D hardness (4.19% and 5.00%), storage modulus (9.88% and 13.07%), loss modulus (7.52% and 17.36%), dielectric constant at 6.5 Hz (13.22% and 23.96%), and significant improvements in the acoustic resonance frequency at 1897 Hz (79.50% and 81%). Peak thermal degradation temperatures of these composites are 420.62 ± 3.43 °C, 439.51 ± 3.54 °C, and 469.07 ± 3.11 °C, respectively, and biodegradability results showing accelerated degradation within 30 days. These findings highlight the substantial effectiveness of treatments in enhancing diverse properties, underscoring the potential applicability of these composites in various industrial sectors requiring superior performance and sustainable materials.

Polymers doi: 10.3390/polym18101188

Authors: Feifan Xie Xiaoyan Zha Xiaoxuan Guo Zongying Fu Yun Lu

To address the global challenge of desertification, it is essential to develop sustainable and biodegradable materials for sand fixation to support ecological restoration in arid regions. In this work, a CNS/PAM biocomposite system was constructed through the supramolecular assembly of highly flexible two-dimensional cellulose nanosheets (CNS) and polyacrylamide (PAM). Benefiting from the flexible layered structure of CNS and the abundant hydroxyl and carboxyl groups on their surface, a conformal coating and an interparticle bridging network were formed via hydrogen bonding and coordination interactions with mineral cations. The introduction of PAM further regulated the hydrogen-bonding network, which improved structural uniformity and mechanical integrity. The resulting composites showed strong resistance to both wind and water erosion (erosion loss < 0.1%) and reached a compressive strength of up to 0.23 MPa, while maintaining good environmental compatibility. This study clarifies the structure–interaction–property relationships of cellulose nanosheet-based supramolecular assemblies and provides a new theoretical basis and practical pathway for designing biodegradable sand-fixing materials.

Polymers doi: 10.3390/polym18101187

Authors: Xiaodong Bai Zeyu Xue Moubo Wang Molin Song Mengqian Yang Jianpeng You Yumei Luo

The temperature-sensitive plugging agent (HAAN) was synthesized via free-radical graft polymerization using hydroxypropyl methyl cellulose (HPMC), acrylamide (AM), 4-acryloylmorpholine (ACMO) and N-vinyl-2-pyrrolidone (NVP) as the main monomers. HAAN demonstrates potential for addressing the frequent lost circulation problems encountered during the drilling of complex formations. The target product was characterized by FTIR and 1H NMR. Its phase transition behavior was verified via temperature-dependent UV-visible transmittance measurements and high-temperature rheological tests. The experimental results show that the plugging agent possesses good temperature and salt tolerance, and its rheological properties can be enhanced by incorporation into drilling fluid. It demonstrates effective plugging performance both at room temperature and under high-temperature conditions, thereby contributing to improved wellbore stability. It provides a new idea for green multifunctional application of cellulose in water-based drilling fluid.

Polymers doi: 10.3390/polym18101186

Authors: Meng Sun Meiyan Wu Ping Wang Bing Li Guang Yu Haishun Du Tao Lou Bin Li

Minimally invasive thread lifting has emerged as an effective strategy for soft tissue repositioning and facial rejuvenation; however, currently used absorbable threads generally lack intrinsic antimicrobial functionality, which may increase the risk of postoperative infection. Here, we report a biodegradable antibacterial lifting thread based on a nanocellulose/MOF composite system. The thread was fabricated via a green wet-spinning strategy using carboxymethylated cellulose nanofibrils (CCNF, prepared with cellulose derived from Astragalus residue) and sodium alginate (SA) as the structural matrix, while tetracycline hydrochloride-loaded ZIF-8 nanoparticles were incorporated to provide sustained antibacterial activity. The resulting antibacterial CCNF/SA thread (AB-CCNF/SA) exhibited a uniform morphology and a tensile strength of 80 MPa. The porous ZIF-8 carriers enabled efficient drug loading and controlled release, providing effective antibacterial activity against Staphylococcus aureus and Escherichia coli. Meanwhile, the composite threads showed favorable biodegradability, with approximately 45% degradation within 56 days, together with excellent cytocompatibility as demonstrated by fibroblast viability above 90%. In vivo studies further revealed inflammatory responses comparable to those of commercial collagen threads, confirming the good biocompatibility of the system. Overall, this work establishes a strategy for integrating nanocellulose structural materials with MOF-enabled antibacterial drug delivery, providing a multifunctional platform that combines mechanical support, biodegradability, and sustained antibacterial activity for minimally invasive soft tissue lifting and related biomedical implant applications.

Polymers doi: 10.3390/polym18101185

Authors: Fernando Júnior Resende Mascarenhas André Luis Christoforo Rogério Manuel Santos Simões Alfredo Manuel Pereira Geraldes Dias André Eduardo Palos Cunha Francisco Antonio Rocco Lahr

Wood–polymer composites (WPCs) produced through monomer impregnation have attracted increasing interest as a strategy to improve the durability and performance of wood materials. However, the limited permeability of certain wood species often restricts the effectiveness of impregnation treatments. This study investigates the use of microwave (MW) pretreatment as a drying and microstructural modification step to enhance methyl methacrylate (MMA) impregnation and in situ polymerization in maritime pine (Pinus pinaster) heartwood specimens. Wood specimens were subjected to MW treatment of 700 W and 5 min cycles prior to vacuum-pressure impregnation with MMA and subsequent thermal polymerization. Scanning electron microscopy and treatability parameters confirmed that MW pretreatment increased wood impregnability by generating microcracks and improving monomer penetration, thereby resulting in higher polymer retention and a higher weight percentage gain. As a result, the combined MW+MMA treatment produced a more homogeneous distribution of polymethyl methacrylate within the wood structure. The modified specimens showed a substantial reduction in water absorption and the highest water repellence efficiency among the studied groups, while dimensional stability improved to a lesser extent. In addition, the combined treatment significantly increased bending strength and stiffness, indicating an effective reinforcement of the wood structure through polymer loading. These results demonstrate that MW pretreatment is an efficient strategy to improve the treatability of maritime pine heartwood and to enhance the performance of MMA-based WPCs.

Polymers doi: 10.3390/polym18101184

Authors: Fernando E. Rodríguez-Umanzor Mauricio A. Sarabia-Vallejos Nicolás F. Acuña-Ruiz Scarleth A. Romero-De la Fuente Nicolás A. Cohn-Inostroza David Ortiz Puerta Enrique Martínez-Campos Juan Rodríguez-Hernández Claudio A. Terraza Inostroza Carmen M. González-Henríquez

Multifunctional scaffolds that combine structural support with the controlled delivery of bioactive agents remain a major challenge in tissue engineering. To extend the use of these devices in biomedicine, 3D printing is presented as an alternative that enables the manufacture of complex devices tailored to each patient, thereby solving specific problems in a timely and efficient manner. In this study, porous 3D scaffolds were fabricated via digital light processing (DLP) using a PET-RAFT resin composed of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and poly(ethylene glycol) diacrylate (PEGDA575). Sodium chloride (NaCl) was incorporated as a porogen, while insulin-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles were embedded as osteoinductive agents. The printed constructs exhibited high-resolution, reproducible trabecular-like architectures, as confirmed by micro-computed tomography (micro-CT), with interconnected pores averaging 70.7 ± 24.7 μm and a total porosity of 57.0 ± 6.98%. Thermal and chemical analyses confirmed scaffold stability and controlled degradability. Cytocompatibility assays using MC3T3-E1, C2C12, hGMSCs, and C166-GFP cells showed viability above 80% after 7 days (ISO 10993-5). Insulin-loaded nanoparticles enabled sustained release, characterized by an initial burst followed by gradual release up to 72 h. Dynamic bioreactor culture enhanced cell adhesion and RUNX2 expression, confirming the osteoinductive potential of the hybrid scaffold for advanced BTE applications. This study introduces an innovative PET-RAFT-derived resin that combines structural reinforcement with spatiotemporal regulation of insulin release, offering a potential strategy for enhanced biomaterial tissue engineering and tailored therapeutic interventions.

Polymers doi: 10.3390/polym18101182

Authors: Geng Hou Zhenzhong Sun

This study aims to establish a quantitative relationship between the color parameters and mechanical properties of thermo-oxidatively aged epoxy resin, with the goal of exploring a low-cost, rapid method for mechanical performance assessment based on color measurement. Epoxy resin specimens were subjected to high-temperature aging for varying durations, after which multiple color parameters were measured using a portable colorimeter. The variations in these parameters with aging duration and intensity were systematically characterized. The results indicate that during thermo-oxidative aging, strength exhibits a monotonic correlation with certain color parameters, such as lightness and hue angle. Based on this finding, an empirical model was developed to estimate strength from color parameter values. A comparison between estimated and experimental results confirms the feasibility and potential of this approach. To make the validation more convincing, it utilized not only the data from this experiment but also data from the literature. This work provides a theoretical basis and a practical technical pathway for utilizing portable colorimeter to rapidly and non-destructively assess the aging extent and mechanical performance of polymeric engineering structures.

Polymers doi: 10.3390/polym18101183

Authors: Vlada Țisari Marius Andrei Mihalache Gheorghe Nagîț Vasile Ermolai Alexandru-Ionuț Irimia Cosmin-Gabriel Grădinaru Alexandra-Anamaria Spiridon Elisaveta Crăciun Roxana-Gabriela Hobjâlă Laurențiu Slătineanu

The use of parts made of polymeric materials has occasionally highlighted the need for them to possess the best possible mechanical properties. One of the currently widely used processes for manufacturing parts from polymeric materials is fused deposition modeling. This process allows for variations in the magnitudes defining the mechanical properties of polymeric materials to be obtained through an appropriate selection of the process input factor values. The analysis of the process has highlighted the primary factors capable of affecting the values of parameters corresponding to the mechanical properties of polymeric materials. The opinions formulated by various researchers regarding the influence of fused deposition modeling application conditions on some of the mechanical properties of polymeric materials have been synthetically and systematically presented. In terms of mechanical properties, tensile strength, compression strength, elongation at break, flexural strength, torsional strength, impact strength, fatigue resistance, and hardness were taken into consideration. Some modeling and optimization solutions for the influence exerted by the 3D printing process input factors on the values of the parameters defining the mechanical properties of polymeric materials in parts manufactured via the FDM process were also highlighted.

Polymers doi: 10.3390/polym18101181

Authors: Jiyu Guan Chao Liu Guang Yu Mohammad Ali Asadollahi Chunxiang Fu Wangda Qu Bin Li

Miscanthus (Panicum virgatum L.), a biomass material known for its rapid growth and high biomass yield, is considered a suitable resource for producing biobased materials. Nevertheless, the dense and complex structure of Miscanthus hinders its full utilization. In this study, alkaline sulfite pretreatment of Miscanthus was carried out to separate the cellulosic fiber fraction and sulfonated lignin. Then, the fiber fraction was used to prepare biobased seedling pots via the wet foaming technique, and the maximum compressive strength of the prepared seeding pot could reach 1317 kPa. The surface coating of the seeding pot with wood wax oil further improved its hydrophobicity and water resistance. Furthermore, the resulting seedling pot with good biodegradability can be used to replace the petroleum-based plastic seedling pot, which could reduce plastic pollution. In addition, the fractionated sulfonated lignin was directly utilized as a fertilizer, showcasing a 6% increase in root and stem height of cabbage and a 15% rise in biomass (dry weight), compared to the humic acid treatment group. Therefore, this work offers a promising and sustainable strategy for the comprehensive utilization of Miscanthus, which can also be a beneficial reference for the better use of other kinds of lignocellulosic biomass.

Polymers doi: 10.3390/polym18101180

Authors: Iclal Avinc Akpinar Simay Bayramoglu Salih Akpinar

In materials science, the increasing use of lightweight and multi-material structures has made improving the interfacial bonding characteristics of polymer-based adhesive systems increasingly important. Accordingly, chemical surface activation and interfacial engineering strategies have attracted considerable attention for enhancing polymer–fiber compatibility and adhesion performance. However, the combined effects of fiber content, surface treatment, and orientation on adhesion behavior remain insufficiently understood. In the present study, natural fibers obtained from the rachis part of the palm tree were chemically modified and incorporated into an epoxy adhesive matrix to investigate the effect of surface functionalization on polymer–fiber interfacial adhesion. In the first stage, the effects of fiber ratios (5–20 wt%) and chemical surface treatments (methanol cleaning and methanol +2–6% HNO3) on adhesion behavior were evaluated. Tensile tests showed that specimens treated with methanol cleaning followed by 4% HNO3 oxidation and containing 10 wt% fiber exhibited an approximately 48% increase in failure load compared to neat joints. In the second stage, the influence of fiber orientation (0–90°) was examined using the optimized parameters. The results indicate that interfacial load-transfer capability increased as the fiber orientation approached perpendicular alignment, reaching maximum performance at 90°. Based on SEM observations, nitric acid treatment was found to increase the surface roughness of the fibers and strengthen the polymer–fiber interfacial bond. FTIR, XPS and contact angle measurements suggested the development of oxygen-containing surface functionalities and improved wettability, consistent with enhanced interfacial adhesion. These findings demonstrate that appropriate chemical surface treatment, fiber content, and orientation can effectively enhance the interfacial adhesion and bonding efficiency of epoxy-based adhesive systems, providing practical guidance for the design of high-performance bonded structures.

Polymers doi: 10.3390/polym18101179

Authors: Yedi Herdiana Syed Mahmood Eli Halimah Ferry Ferdiansyah Sofian

Marine polymers have attracted a lot of attention as potential alternatives to the traditional animal-derived polymers in pharmaceutical formulation since they are abundant, biocompatible, and versatile in functionality. However, the presence of these materials in dosage-form studies, often in support of proof-of-concept trials, does not mean they are ready to apply as excipients routinely. This review critically evaluates the reasons why three of the most highly researched marine-derived polymers, chitosan, alginate, and carrageenan, continue to encounter significant translational barriers in pharmaceutical excipient development. All three polymers have been demonstrated to have clear pharmaceutical utility; however, their behavior is highly dependent on source, structure, processing history and formulation context. Chitosan explains why functional benefits may be compromised by responses to material requirements; alginate explains why apparent proximity to use may not remove composition-related variability; and carrageenan explains that even seemingly simple rheological functions may be very context-dependent. All of this points to the fact that the major hurdle lies not in the lack of potential, but in the difficulty of achieving the required degree of control, reproducibility, and manufacturability in order to make the reliable use of excipients possible. Future progress in this field will likely require a shift from descriptive exploration toward readiness-focused evidence, including demonstrated control over material attributes, reproducible performance, and feasible qualification pathways.

Polymers doi: 10.3390/polym18101178

Authors: Jolanta Wąs-Gubała Weronika Sarnowska Bartłomiej Feigel

The objective of this study was to evaluate colour changes in cotton fibres within knitted fabric structures under different light exposure conditions and to assess the applicability of forensic analytical methods for this purpose. Fabrics of three distinct colours were exposed to two types of irradiation: natural sunlight and artificial light in a controlled climatic chamber. A multi-scale analytical approach was applied, including visual inspection and stereomicroscopy for macro-level evaluation, followed by bright-field microscopy, fluorescence microscopy, and UV–Vis microspectrophotometry for single-fibre characterisation. Visual assessment of fabrics revealed perceptible colour differences between exposed and unexposed samples, whereas stereomicroscopy did not consistently enhance the detection of these alterations. Bright-field and fluorescence microscopy showed no visually perceptible differences between fibres from exposed and unexposed fabrics of the same colour. Microspectrophotometric measurements did not reliably capture colour changes in single cotton fibres, particularly in samples exposed to natural sunlight. Furthermore, total colour difference (ΔE) values, ranging from 0.248 to 6.652, were found to be unreliable at the single-fibre level due to significant spatial variability across different measurement sites. The findings indicate that, while light exposure may induce perceptible colour alterations in cotton knitted fabrics, the forensic examination of single fibres does not necessarily reflect these macro-scale changes. From a forensic perspective, the stability of microscopic and microspectrophotometric characteristics supports reliable fibre comparison, even after post-event exposure to sunlight.

Polymers doi: 10.3390/polym18101177

Authors: Jiangchun Qin Lina Dong Hengyan Tian Fei Yang Jiayang Hu Dengbang Jiang Zhonghui Zhang

The complete removal of persistent aromatic organic pollutants from aqueous environments demands the development of sustainable and highly efficient filtration materials. In this study, novel bio-sourced mixed-matrix membranes (MMMs) were successfully fabricated by incorporating the highly porous metal–organic framework MIL-68(Al) into a biodegradable polylactic acid (PLA) matrix via a solvent-induced phase inversion method. The integration of MIL-68(Al) nanoparticles significantly tailored the membrane’s morphological structure, endowing the hybrid membranes with enhanced surface hydrophilicity (water contact angle reduced from 90.3° to 72.7°) and superior permeability. The pure water flux reached an optimal value of 42.2 L m−2 h−1 at a 15 wt.% MOF loading. Crucially, the hybrid membranes exhibited exceptionally high adsorptive removal performance for p-nitrophenol (PNP) and methylene blue (MB). Driven by the abundant accessible active sites of the MOF filler, the MIL-20/PLA membrane achieved a maximum equilibrium adsorption capacity of 121.03 μg/cm2 (36.90 mg/g) for PNP, representing a remarkable 25.7-fold enhancement over the pristine PLA membrane. Kinetic analyses confirmed that the adsorption process is strictly governed by pseudo-second-order kinetics, indicating a chemisorption mechanism dominated by hydrogen bonding and π–π stacking interactions. Furthermore, the optimized membranes demonstrated outstanding dynamic filtration efficiencies (>80%) and robust regenerability over multiple continuous operating cycles. This work not only highlights the synergistic interfacial effects between MOFs and biodegradable polymers but also provides a highly effective, eco-friendly, and sustainable membrane platform for the advanced remediation of organic-contaminated wastewater.

Polymers doi: 10.3390/polym18101176

Authors: Maria-Paraskevi Belioka

The rapid accumulation of plastic waste has become a major environmental concern, while at the same time, it is necessary to create opportunities to rethink how these materials can be reintegrated into productive use, particularly within the construction sector. This study provides a sustainability-oriented review of the reuse of plastic waste, both fossil-based plastics and bioplastics, as building materials, with a specific emphasis on structured decision-support approaches. A systematic literature review was conducted to identify and analyze peer-reviewed studies examining the incorporation of plastic waste into construction applications, including composites, panels, insulation systems, and structural or non-structural components. Particular attention is given to research applying Multi-Criteria Decision Analysis (MCDA) and SWOT analysis as tools for evaluating sustainability performance across environmental, economic, technical, and social dimensions. The findings indicate that recycled plastic and bioplastic-based construction materials can deliver significant advantages, such as diverting waste from disposal pathways, reducing reliance on virgin resources, and, in certain cases, enhancing durability. However, these materials also face important challenges, including limitations in recyclability, concerns related to fire performance, regulatory acceptance, and uncertainties in end-of-life management. MCDA-based studies underscore the critical role of criteria selection and weighting, especially regarding environmental impact reduction and cost competitiveness, in shaping final rankings and decision outcomes. SWOT analyses, in turn, offer complementary strategic insights by highlighting issues related to market readiness, regulatory frameworks, and implementation barriers. By integrating these decision-oriented evaluation approaches, this review contributes to more transparent and evidence-based material selection processes and supports policy development aimed at strengthening circular economy strategies for plastic waste reuse in the built environment.

Polymers doi: 10.3390/polym18101175

Authors: Emmanuel Flores-Huicochea Magarito Somera-González Monserrat Morales-Catalán Claudia Andréa Romero-Bastida Allison Vianey Valle-Bravo Carlos López-González Amalia Irais Cuno-Jaimes Rosalía América González-Soto

Chickpea (Cicer arietinum L.) flour is a promising raw material for bio-based packaging due to its protein and polyphenol content. In this study, thermocompressed chickpea flour sheets were reinforced with cellulose nanocrystals (CNCs) to improve their barrier, mechanical, optical, thermal, and structural properties. Preliminary trials identified 22% moisture as the most suitable condition for consistent sheet formation. CNC was incorporated at 0, 2.5, 5.0, and 7.5% (w/w). Thermocompression reduced the measurable phenolic fractions, although antioxidant activity was not significantly affected. CNC markedly reduced water vapor permeability from 5.16 × 10−10 in the control to 5.93 × 10−12 g∙m−1∙s−1∙Pa−1 at 7.5% CNC. Tensile strength and Young’s modulus increased with CNC loading, whereas elongation at break was highest at intermediate concentrations. Optical characterization showed changes in transmittance and opacity. Thermal analysis indicated that CNC modified the DSC thermal event, whereas only minor differences were observed in the TGA profile. SEM, DSC, XRD, and FTIR analyses suggested changes in morphology and thermo-structural organization. Overall, CNC improved barrier and mechanical performance, supporting the potential of these sheets as a material for semirigid biodegradable packaging applications.

Polymers doi: 10.3390/polym18101174

Authors: Zuzana Mitaľová Jakub Kaščak Marek Kočiško Juliána Litecká

The article focuses on the potential of recycled materials for the production of 3D printing filaments.. The individual parts are focused on defines the relationship between circular economy/3D printing technology, and the key motivations for the use of recyclates in the context of sustainability. Core of the article describes different types of recycled polymers, with emphasis on the number of recycling cycles and the associated changes in material properties. It also includes a discussion of degradation processes resulting from repeated thermal loading, i.e., mechanical recycling. Simultaneously, individual recyclates are comparatively evaluated in terms of mechanical properties, rheological characteristics (particularly the melt flow index), and their processability in 3D printing. Furthermore, key challenges are identified, and perspective directions for future research in this field are outlined.

Polymers doi: 10.3390/polym18101173

Authors: Azizollah Khormali Soroush Ahmadi

Calcium sulfate scale formation is a major challenge in oilfield production systems. In this study, the performance of phosphino-polycarboxylic acid (PPCA) as a polymeric scale inhibitor was evaluated using static jar tests and modeled using Response Surface Methodology (RSM). The effects of temperature (50–100 °C), inhibitor concentration (10–50 ppm), and calcium ion concentration (1000–10,000 ppm) on inhibition efficiency (IE%) were investigated through 60 experimental runs. The results showed that IE% varied from 33.7% to 95.4%, depending on operating conditions. A quadratic RSM model demonstrated excellent predictive capability (R2 = 0.9977) with a low average error of 1.4%. Among the variables, inhibitor concentration had the strongest effect, followed by calcium ion concentration and temperature. Increasing PPCA concentration significantly improved inhibition efficiency, exceeding 90% at dosages above 35 ppm, while higher temperature and calcium concentration reduced performance. Response surface analysis indicated that IE% above 94% could be achieved at 43–50 ppm inhibitor and temperatures below 63 °C. Under harsh conditions (100 °C and 10,000 ppm Ca2+), 42–50 ppm PPCA maintained IE above 90%, with a predicted maximum of 90.81%. These results confirm the effectiveness of PPCA and provide a reliable basis for optimizing scale inhibition performance.

Polymers doi: 10.3390/polym18101172

Authors: Joaquin Hernandez-Fernandez Rafael Gonzalez-Cuello Rodrigo Ortega-Toro

This study evaluates the non-catalytic thermal pyrolysis of post-consumer polystyrene (PS) in a laboratory-scale batch fixed-bed reactor to recover aromatic-rich liquid products. The PS feedstock was characterized by thermogravimetric analysis (TGA) and micro-Raman spectroscopy to assess its thermal behavior and chemical homogeneity. In addition, the main TGA degradation region was analyzed using Coats–Redfern, Horowitz–Metzger, and Broido kinetic models, yielding apparent activation energies of 269.18, 288.83, and 280.69 kJ mol−1, respectively. Pyrolysis experiments were performed at final temperatures of 400, 450, and 500 °C and heating rates of 10 and 20 °C min−1 under continuous N2 flow. The maximum liquid yield reached 95.2 wt% at 500 °C and 20 °C min−1, while the estimated gaseous fraction decreased to approximately 2.0 wt%. ANOVA confirmed that final temperature was the dominant factor controlling liquid recovery, contributing approximately 83% of the model variability, whereas heating rate had a secondary but significant effect. GC–MS analysis showed that the pyrolysis oil was mainly composed of aromatic hydrocarbons, including styrene, toluene, and ethylbenzene, with increasing temperature promoting the redistribution of the liquid fraction toward lighter monoaromatic compounds. These results indicate that non-catalytic fixed-bed pyrolysis is a promising route for converting post-consumer PS into aromatic-rich liquid products. However, the recovered oil should be considered a complex mixture rather than a purified monomer stream, and further gas-phase characterization, downstream purification, energy-balance evaluation, life-cycle assessment, and techno-economic analysis are required before definitive claims regarding industrial circularity or environmental performance can be established.

Polymers doi: 10.3390/polym18101170

Authors: Shunming Yao Lihua Zhan Chenglong Guan Dechao Zhang Miaomiao Zhang

Composite components with variable-thickness structures often suffer from insufficient forming pressure during curing due to complex pressure transfer in regions with abrupt thickness changes, which easily causes void defects and degrades component performance. In this study, a mechanical vibration-assisted double vacuum bag process is proposed. Finite element analysis of the vibration energy field in saturated porous composites is conducted, and curing experiments for variable-thickness specimens are designed. The effects of vibration, vacuum, and their synergy on void characteristics and mechanical properties are studied using microscopic characterization and mechanical tests. The results indicate that vibration can effectively facilitate gas discharge and accelerate resin flow, while the double vacuum bag process reduces gas discharge resistance in the early curing stage by delaying the vacuum negative pressure application, yet it also results in insufficient resin flow due to this delay. Through the synergistic optimization of vibration-assisted energy field parameters and the double vacuum bag process, gas-induced and flow-induced voids can be effectively suppressed while ensuring curing efficiency, reducing the macroscopic porosity of variable-thickness regions from 8.34% (single vacuum bag process) to 0.43%. This study provides a new approach for the high-quality curing and manufacturing of variable-thickness composite components.

Polymers doi: 10.3390/polym18101171

Authors: Nan Zhang Jinrong Zhang Kaishan Yu Yang Qiao Pengfei Cui Chengzhao Yang Minglun Li

Protein recognition underpins advances in drug discovery, immunoassays, clinical diagnostics and biosensing. As a biomimetic alternative to natural receptors, molecularly imprinted polymers (MIPs) have been developed to emulate antibody–antigen complementarity by generating binding cavities that mirror the size, shape and functionality of target macromolecules through template-directed polymerization and subsequent template removal. However, protein imprinting has historically been hampered by low imprinting efficiency and limited selectivity, rendering conventional protein-imprinted polymers (PIPs) inadequate for many contemporary biomedical applications. Functional ionic liquids (ILs)—a class of designer solvents and materials distinguished by tunable structures, exceptional physicochemical properties and favorable biocompatibility—have emerged as versatile additives to address the principal limitations of traditional PIPs, including poor selectivity, sluggish mass transfer and destabilization of protein conformation. Here, we provide a systematic review of the multifaceted roles that ILs play within protein-imprinting systems, delineating their employment as template-anchoring motifs, functional monomers, cross-linkers, porogens and structural stabilizers, and evaluating the consequent effects on polymer architecture and recognition performance. We further probe the multiplicity of non-covalent interactions between ILs and template proteins—highlighting the synergistic modulation afforded by electrostatic forces, hydrogen bonding, hydrophobic interactions and π-π stacking—and consider how such interplay can be harnessed to fine-tune binding-site fidelity. Consolidating recent progress, we summarize IL-enabled PIP applications in protein-specific recognition, biosensor development and analysis of complex real-world samples, and we critically examine the prevailing technical challenges and prospects for translation. The evidence indicates that ILs, by furnishing abundant interaction sites, accelerating mass transport and stabilizing native protein conformations, can markedly enhance PIP adsorption capacity, target specificity and recyclability, positioning them as a cornerstone for next-generation protein separation and enrichment materials and paving the way toward industrial deployment of protein-imprinting technologies.

Polymers doi: 10.3390/polym18101169

Authors: Jianghuai Zhan Xuanyi Xue Haolan Yi Fei Wang Shuai Li Jianmin Hua

This study investigated the effects of freeze–thaw cycles on unreinforced and basalt fiber-reinforced lunar regolith simulant (LRS) geopolymer. Specimens were subjected to 0, 3, 6, and 10 freeze–thaw cycles. Compressive strength, flexural strength, elastic modulus, peak strain, and failure mode were measured. Damage degree and gain ratio were used to evaluate fiber reinforcement. Results showed that the unreinforced LRS geopolymer exhibited considerable fluctuation in compressive strength during freeze–thaw cycles. Its compressive strength first increased, then decreased; its flexural strength continuously declined; and its elastic modulus and peak strain showed opposite trends, with typical brittle failure. In contrast, basalt fiber-reinforced LRS geopolymer demonstrated superior frost resistance. Its compressive strength increased continuously with freeze–thaw cycles, reaching 23.5% after 10 cycles. Its flexural strength decreased but stabilized, with a damage level of only 16.0% after 10 cycles, significantly lower than that of the unreinforced group (26.1%). Its elastic modulus increased continuously while peak strain decreased gradually, with failure exhibiting some ductile characteristics. Gain ratio analysis showed compressive and flexural strength gain ratios of 1.92 and 1.69, respectively, after 10 cycles, indicating significant reinforcement. Among three classical constitutive models (Guo Zhenhai, Saenz L.P., and Carreira D.J.), the Guo Zhenhai model provided the best fit for stress–strain curves of both geopolymer types under all freeze–thaw conditions, making it the recommended constitutive model. This study provides theoretical support for LRS geopolymer applications in extreme environments such as the lunar surface.

Polymers doi: 10.3390/polym18101168

Authors: Vicente Martínez Félix Arto-Paz Maribel Mamani Ricardo I. Castro Silvana Moris Darío M. González Cristian Valdés

Kefiran is a bioactive exopolysaccharide produced by kefir grains, whose synthesis is strongly influenced by culture medium composition. In this study, cheese whey was evaluated as an alternative fermentation substrate for kefiran production, and the effect of supplementation with fermentable sugars (glucose, galactose, and lactose) and casein was assessed under controlled conditions. Kefir grains were cultivated in whey- and milk-based media, and kefiran production was quantified using an anthrone-based method, while grain growth and carbohydrate consumption were monitored. Supplementation with sugars and casein reduced kefiran production by up to 34.6% and did not improve yield, whereas unsupplemented whey supported the highest kefiran concentration (86.9 ± 3.7 mg/L), comparable to that obtained in semi-skimmed milk (84.0 ± 3.0 mg/L). The recovered polysaccharide was characterized by Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), showing structural and physicochemical properties comparable to kefiran obtained from semi-skimmed milk. These results indicate that whey constitutes a feasible and simple fermentation medium for kefiran production, and that increased medium complexity does not necessarily improve process performance.

Polymers doi: 10.3390/polym18101167

Authors: Eylul Kosoglu Asude Sena Demirci Ulke Yasar Andelib Aydin

Hydrothermally treated chitosan/polyvinyl alcohol beads (H-CS/PVA) were used as filler material in a fixed-bed column for continuous Cr (VI) removal. The effects of main operational parameters, namely bed height, initial concentration and flow rate, were evaluated in the respective ranges of 2–6 cm, 20–60 mg/L and 2.5–7.5 mL/min. Maximum removal efficiency and adsorption capacity were calculated as 64.2% and 15.53 mg/g, respectively. The corresponding breakthrough curves were analyzed by Yoon–Nelson, Adams–Bohart, Thomas and BDST (Bed Depth–Service Time) models, out of which the highest consistency was achieved with the Yoon–Nelson model for all studied conditions. The adsorbent maintained strong reusability, showing minimal loss (~2.5%) in desorption efficiency across three successive regeneration cycles with 0.1 M NaOH as the eluent. SEM and SEM–EDX analyses confirmed the presence of chromium on the H-CS/PVA surface at an elemental fraction of 1.03% (w.). Furthermore, FTIR and XPS analyses verified the role of amine and hydroxyl functionalities in the complexation and adsorption of Cr (VI). Overall, a column system operated under optimal conditions (Hbed: 6 cm, C0: 40 mg/L, and column diameter: 2.5 cm) and regenerated three times can efficiently treat 20 L of Cr (VI)-contaminated wastewater, resulting in an associated environmental impact of 0.896 kg CO2-eq.