Polymers

17 pages, 4302 KiB

Open AccessArticle

Effect of the Interior Fill Percentage on the Deterioration of the Mechanical Properties of FFF-3D-Printed PLA Structures

by Akira Yamada and Kanta Tatebe

Polymers 2025, 17(6), 828; https://doi.org/10.3390/polym17060828 - 20 Mar 2025

Viewed by 215

Abstract

Poly (lactic acid) (PLA), a biodegradable polymer, is widely used in medical applications, particularly for 3D-printed tissue engineering scaffolds. The fused filament fabrication (FFF) 3D printer is an available processing tool for PLA. The nozzle scan pattern and interior fill percentage (IFP) considerably [...] Read more.

Poly (lactic acid) (PLA), a biodegradable polymer, is widely used in medical applications, particularly for 3D-printed tissue engineering scaffolds. The fused filament fabrication (FFF) 3D printer is an available processing tool for PLA. The nozzle scan pattern and interior fill percentage (IFP) considerably influence the mechanical properties of formed structures and may have dominant effects on the rates at which the mechanical properties of PLA deteriorate. When the IFP is set to a low value, such as 80%, internal gaps form within the structure, leading to different deterioration patterns compared to structures formed under the IFP 100% condition. In this study, we fabricated test pieces with an FFF 3D printer using three different nozzle scan patterns. After immersing the test pieces in phosphate buffer saline (PBS) for up to 120 days, the water content was measured and the test pieces underwent tensile testing to determine the tensile strength, elastic modulus, and breaking energy. Both the deterioration rate and water uptake rate varied among the different nozzle scan patterns used for the fabrication. For the test pieces formed with internal gaps, the water uptake and deterioration proceeded in two stages. The deterioration rate of the structures with internal gaps was faster than that of the fully filled structures. The data obtained in this study will be useful for the design of PLA structures applied in tissue engineering. Full article

(This article belongs to the Special Issue Three-Dimensional Printing of Polymer Materials)

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18 pages, 5670 KiB

Open AccessArticle

Optimization of Water Plugging Characteristics and Mechanical Properties of Acrylate Grouting Materials Based on Composite Crosslinking Strategy

by Fengxian Yu, Langtian Qin, Deqiang Han and Feng Huang

Polymers 2025, 17(6), 827; https://doi.org/10.3390/polym17060827 - 20 Mar 2025

Viewed by 174

Abstract

Traditional acrylate grouting materials often suffer from mechanical performance degradation and interfacial bonding failure under long-term water immersion, significantly limiting their application in pressurized water environments. This study proposes a composite crosslinking synergistic strategy to address these challenges. By constructing a dual-network structure [...] Read more.

Traditional acrylate grouting materials often suffer from mechanical performance degradation and interfacial bonding failure under long-term water immersion, significantly limiting their application in pressurized water environments. This study proposes a composite crosslinking synergistic strategy to address these challenges. By constructing a dual-network structure through polyethylene glycol diacrylate (PEG500DA) and a monofunctional crosslinker (PEG-MA), and systematically optimizing the material formulation by regulating the triethanolamine content to control gelation time, the mechanical and hydraulic stability of the material was significantly enhanced. Increasing the acrylate concentration to 35% achieved an optimal balance between a slurry viscosity (8.3 mPa·s) and mechanical performance, with tensile strength reaching 76 kPa and the compressive strength of the sand-solidified body measuring 440 kPa. At a PEG500DA/PEG-MA ratio of 2:3, the material exhibited both high tensile strength (78 kPa) and exceptional ductility (elongation at break > 407%), with a compressive strength of 336 kPa for the sand-solidified body. When the total crosslinker content exceeded 5%, the 28-day water absorption and volume expansion rates were effectively reduced to 12% and 11%, respectively. Under simulated pressurized water conditions, the modified material demonstrated a water-pressure resistance of 300 kPa after 1 day, stabilizing at 350 kPa after 56 days—a 75% improvement over commercial products. This study provides an innovative solution for long-term anti-seepage applications in complex hydrogeological environments, offering significant advancements in material design and engineering reliability. Full article

(This article belongs to the Section Polymer Chemistry)

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15 pages, 6050 KiB

Open AccessArticle

Synthesis of Polymer Sodium Alginate–Red Mud Adsorbent and Its Application in the Removal of Low-Concentration Fluoride

by Jiahao Wang, Huali Zhang, Nenghao Wang, Han Mo, Zhen Yang, Yangyang Dong, Qingwei Liu, Xiao Huang and Baoyi Han

Polymers 2025, 17(6), 826; https://doi.org/10.3390/polym17060826 - 20 Mar 2025

Viewed by 226

Abstract

The sustainable management of industrial byproducts represents a critical challenge for the aluminum industry. This study developed a cost-effective adsorbent (SA@RM) derived from sodium alginate and red mud for fluoride removal, addressing both solid waste utilization and water purification needs. Systematic adsorption experiments [...] Read more.

The sustainable management of industrial byproducts represents a critical challenge for the aluminum industry. This study developed a cost-effective adsorbent (SA@RM) derived from sodium alginate and red mud for fluoride removal, addressing both solid waste utilization and water purification needs. Systematic adsorption experiments revealed optimal performance under conditions of 15 g/L dosage and pH 5, achieving adsorption equilibrium within 40 min for initial fluoride concentrations of 11.7 mg/L. Notably, the adsorbent demonstrated exceptional cyclic stability, maintaining 54.8% adsorption capacity through three regeneration cycles. The adsorption process followed the Langmuir isotherm model (R² = 0.994) and pseudo-second-order kinetics (R² = 0.975), indicating monolayer chemisorption as the dominant mechanism. Advanced characterization techniques (SEM-EDS, FT-IR, XPS) elucidated three main mechanisms: fluoride complexation with aluminum oxides, ligand exchange with surface hydroxyl groups, and ion exchange with chloride species. This material achieves 92% fluoride removal while valorizing industrial waste, reducing adsorbent production costs by 60–70% compared to conventional materials. The detailed mechanism analysis provides fundamental insights for designing waste-derived adsorbents, offering a practical solution for sustainable industrial development and water treatment applications. Full article

(This article belongs to the Section Biobased and Biodegradable Polymers)

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15 pages, 4702 KiB

Open AccessArticle

Dynamics of Polymeric Re-Entrant Auxetic Structures: Cyclic Compression Studies

by Julian Plewa, Małgorzata Płońska and Grzegorz Junak

Polymers 2025, 17(6), 825; https://doi.org/10.3390/polym17060825 - 20 Mar 2025

Viewed by 234

Abstract

The present study investigated the dynamic behavior of structures made of re-entrant unit cells subjected to cyclic compressive loading limited to the elastic range. The structures were assembled from printed polymer re-entrant cells in six combinations. Through the given compression cycles for three [...] Read more.

The present study investigated the dynamic behavior of structures made of re-entrant unit cells subjected to cyclic compressive loading limited to the elastic range. The structures were assembled from printed polymer re-entrant cells in six combinations. Through the given compression cycles for three different amplitude values, strain-force relationships, which had the shape of a hysteresis loop, were obtained. Under compression, all unit cells of the structures deformed uniformly, though only for a certain amount of strain, whereas with larger changes, they underwent uncontrolled deformation. Experiments showed that structures composed of more than one unit cell exhibit different mechanical characteristics. It was observed that the width of the hysteresis loop depended on the degree of closing the structure and on the compression amplitude. The obtained hysteresis curves for different amplitudes also testify to the occurrence of the Mullins effect for these polymeric auxetic structures. Taking into account the maximum values of changes in dimensions for a given compression cycle, Poisson’s ratio values were determined, which were negative and below unity. The effect of strut thickness on the NPR was confirmed, decreasing its negative value along with the increasing thickness. Full article

(This article belongs to the Special Issue Polymer Physics: From Theory to Experimental Applications: 2nd Edition)

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18 pages, 8199 KiB

Open AccessArticle

Microfluidization Preparation of Hybrid Graphene for Enhanced Wear Resistance of Coatings

by Qi Chen, Na Wang, Dhandapani Kuzhandaivel, Yingxian Chen, Lixin Wu and Longhui Zheng

Polymers 2025, 17(6), 824; https://doi.org/10.3390/polym17060824 - 20 Mar 2025

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Abstract

Wear resistance is the key factor that affects the long-term use of leather. Graphene has excellent wear resistance properties, but ensuring the effective dispersion of graphene in resin is crucial for determining the performance of the material. In this work, silica modified with [...] Read more.

Wear resistance is the key factor that affects the long-term use of leather. Graphene has excellent wear resistance properties, but ensuring the effective dispersion of graphene in resin is crucial for determining the performance of the material. In this work, silica modified with polydopamine (SiO₂@PDA) was used as an exfoliation agent. Using the microfluidization process and water as the medium, silica-graphene hybrid nanoparticles (SiO₂@PDA-G) were prepared from expanded graphite. These nanoparticles were further compounded with waterborne polyurethane (WPU), and a superfine fiber-based fabric was used as the substrate to prepare composite coating. The results showed that the high shear force of the microfluidization process easily broke up the lamellar structure of graphite, resulting in few-layer graphene. Nano-silica was adsorbed on the surface of graphene, preventing re-aggregation between the graphene sheets. Compared to the WPU coating, the presence of SiO₂@PDA-G improved the wear resistance and mechanical properties of the coating. The wear rate and the average friction coefficient of the composite coating decreased by 48% and 69%, respectively, and the tensile strength increased by 83%. Therefore, this study provides a new strategy for improving the dispersion of graphene in polymer materials and enhancing the abrasion resistance of the coatings. Full article

(This article belongs to the Special Issue Graphene-Based Polymer Composites and Their Applications II)

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17 pages, 3161 KiB

Open AccessArticle

Unpacking Online Discourse on Bioplastics: Insights from Reddit Sentiment Analysis

by Bernardo Cruz, Aimilia Vaitsi, Samuel Domingos, Catarina Possidónio, Sílvia Luís, Eliana Portugal, Ana Loureiro, Sibu Padmanabhan and Ana Rita Farias

Polymers 2025, 17(6), 823; https://doi.org/10.3390/polym17060823 - 20 Mar 2025

Viewed by 401

Abstract

Bioplastics have been presented as a sustainable alternative to products derived from fossil sources. In response, industries have developed innovative products using biopolymers across various sectors, such as food, packaging, biomedical, and construction. However, consumer acceptance remains crucial for their widespread adoption. This [...] Read more.

Bioplastics have been presented as a sustainable alternative to products derived from fossil sources. In response, industries have developed innovative products using biopolymers across various sectors, such as food, packaging, biomedical, and construction. However, consumer acceptance remains crucial for their widespread adoption. This study aims to explore public sentiment toward bioplastics, focusing on emotions expressed on Reddit. A dataset of 5041 Reddit comments was collected using keywords associated with bioplastics and the extraction process was facilitated by Python-based libraries like pandas, NLTK, and NumPy. The sentiment analysis was conducted using the NRCLex, a broadly used lexicon. The overall findings suggest that trust, anticipation, and joy were the most dominant emotions in the time frame 2014–2024, indicating that the public emotional response towards bioplastics has been mostly positive. Negative emotions such as fear, sadness, and anger were less prevalent, although an intense response was noted in 2018. Findings also indicate a temporal co-occurrence between significant events related to bioplastics and changes in sentiment among Reddit users. Although the representativeness of the sample is limited, the results of this study support the need to develop real-time monitoring of the public’s emotional responses. Thus, it will be possible to design communication campaigns more aligned with public needs. Full article

(This article belongs to the Special Issue Environment-Friendly Polymers: Synthesis, Processing and Applications (2nd Edition))

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30 pages, 2524 KiB

Open AccessReview

Extracellular Matrix Stiffness: Mechanotransduction and Mechanobiological Response-Driven Strategies for Biomedical Applications Targeting Fibroblast Inflammation

by Watcharaphol Tiskratok, Nontawat Chuinsiri, Phoonsuk Limraksasin, Maythwe Kyawsoewin and Paiboon Jitprasertwong

Polymers 2025, 17(6), 822; https://doi.org/10.3390/polym17060822 - 20 Mar 2025

Viewed by 639

Abstract

The extracellular matrix (ECM) is a dynamic network providing mechanical and biochemical cues that regulate cellular behavior. ECM stiffness critically influences fibroblasts, the primary ECM producers, particularly in inflammation and fibrosis. This review explores the role of ECM stiffness in fibroblast-driven inflammation and [...] Read more.

The extracellular matrix (ECM) is a dynamic network providing mechanical and biochemical cues that regulate cellular behavior. ECM stiffness critically influences fibroblasts, the primary ECM producers, particularly in inflammation and fibrosis. This review explores the role of ECM stiffness in fibroblast-driven inflammation and tissue remodeling, focusing on the physicochemical and biological mechanisms involved. Engineered materials, hydrogels, and polydimethylsiloxane (PDMS) are highlighted for replicating tissue-specific stiffness, enabling precise control over cell–matrix interactions. The surface functionalization of substrate materials, including collagen, polydopamine, and fibronectin, enhances bioactivity and fibroblast adhesion. Key mechanotransduction pathways, such as integrin signaling and YAP/TAZ activation, are related to regulating fibroblast behaviors and inflammatory responses. The role of fibroblasts in driving chronic inflammatory diseases emphasizes their therapeutic potentials. Advances in ECM-modifying strategies, including tunable biomaterials and hydrogel-based therapies, are explored for applications in tissue engineering, drug delivery, anti-inflammatory treatments, and diagnostic tools for the accurate diagnosis and prognosis of ECM stiffness-related inflammatory diseases. This review integrates mechanobiology with biomedical innovations, providing a comprehensive prognosis of fibroblast responses to ECM stiffness and outlining future directions for targeted therapies. Full article

(This article belongs to the Special Issue Biomedical Applications of Polymeric Materials II)

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17 pages, 4497 KiB

Open AccessArticle

Adhesion of Mesenchymal Stem Cells to Glycated Collagen—Comparative Analysis of Dynamic and Static Conditions

by Regina Komsa-Penkova, Anika Alexandrova-Watanabe, Svetla Todinova, Violina Ivanova, Svetoslava Stoycheva, Petar Temnishki, Borislav Dimitrov, Dobromir Dimitrov, Pencho Tonchev, Galya Georgieva, Aleksandar Kukov, Izabela Ivanova, Tihomir Tiankov, Emilia Abadjieva, Velichka Strijkova and George Altankov

Polymers 2025, 17(6), 821; https://doi.org/10.3390/polym17060821 - 20 Mar 2025

Viewed by 281

Abstract

Understanding mesenchymal stem cell (MSC) behavior on glycated collagen is crucial for advancing regenerative medicine and understanding pathological mechanisms in diseases such as diabetes, cancer, and aging. While previous research has demonstrated reduced MSC interaction with glycated collagen under static conditions due to [...] Read more.

Understanding mesenchymal stem cell (MSC) behavior on glycated collagen is crucial for advancing regenerative medicine and understanding pathological mechanisms in diseases such as diabetes, cancer, and aging. While previous research has demonstrated reduced MSC interaction with glycated collagen under static conditions due to disrupted integrin signaling, these studies did not accurately replicate the dynamic mechanical environment that MSCs encounter in vivo. Here we present a comprehensive investigation comparing adipose-derived MSC (ADMSC) behavior under both dynamic flow conditions and static adhesion, revealing unexpected temporal dynamics and challenging existing paradigms of cell–matrix interactions. Using a sophisticated microfluidic BioFlux system combined with traditional static adhesion assays, we examined ADMSC interactions with native collagen for 1-day glycated (GL1), and 5-day glycated (GL5) samples. Under flow conditions, MSCs demonstrated remarkably rapid attachment—within 3–5 min—contrasting sharply with the classical 2 h static incubation protocol. This rapid adhesion was particularly enhanced on 5-day glycated collagen, though subsequent testing revealed significantly weaker adhesion strength under shear stress compared to native collagen. Static conditions also showed a distinct pattern: increased ADMSC adhesion to glycated samples within the first 30 min, followed by a progressive decrease in adhesion and compromised cell spreading over longer periods. Atomic force microscopy (AFM) analysis revealed significant changes in collagen surface properties upon glycation. These included a substantial reduction in the negative surface charge (from ~800 to 600 mV), altered surface roughness patterns (Rrms varying from 3.0 ± 0.4 nm in native collagen to 7.70 ± 0.6 nm in GL5), and decreased elasticity (Young’s modulus dropping from 34.8 ± 5.4 MPa to 2.07 ± 0.3 MPa in GL5). These physical alterations appear to facilitate rapid initial cell attachment while potentially compromising long-term stable adhesion through traditional integrin-mediated mechanisms. This study provides novel insights into the complex dynamics of MSC adhesion to glycated collagen, revealing previously unknown temporal patterns and challenging existing models of cell–matrix interactions. The findings suggest a need for revised approaches in tissue engineering and regenerative medicine, particularly in conditions where glycated collagen is prevalent. Full article

(This article belongs to the Special Issue Advanced Polymers for Medical Applications, 2nd Edition)

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18 pages, 3960 KiB

Open AccessArticle

Characterization of Properties and Kinetic Analysis of Unsaturated Polyester Resin Synthesized from PET Alcoholysis Waste

by Ruixiang Wang, Hongliang Zhang, Jingshuang Liu and Tongjun Wei

Polymers 2025, 17(6), 820; https://doi.org/10.3390/polym17060820 - 20 Mar 2025

Viewed by 261

Abstract

Recycling and reutilization of waste PET through alcoholysis has been a prominent focus of current research. However, the alcoholysis process is reversible, leading to the generation of oligomeric waste byproducts. To further utilize these wastes, this paper processed oligomeric waste derived from various [...] Read more.

Recycling and reutilization of waste PET through alcoholysis has been a prominent focus of current research. However, the alcoholysis process is reversible, leading to the generation of oligomeric waste byproducts. To further utilize these wastes, this paper processed oligomeric waste derived from various alcoholysis systems to synthesize unsaturated polyester resins (UPRs). The fundamental characteristics, mechanical properties, and curing processes of synthesized UPRs were analyzed based on GPC, FTIR, TG, tensile testing, DMA, and DSC tests. The results indicate that wastes were successfully synthesized to UPRs. The UPRs synthesized from ethylene glycol (EG) and diethylene glycol (DEG) possess more complex compositions; among these, the UPR synthesized from EG exhibited higher thermal stability, whereas the UPR synthesized from DEG showed a broader molecular weight distribution and a lower glass transition temperature (T_g). In addition, the UPR synthesized from DEG exhibited a remarkably high elongation at break (>180%), potentially attributed to its long molecular chains. Regarding curing characteristics, UPRs obtained from DEG and propylene glycol (PG) exhibited slower curing rates and demanded higher activation energies. Moreover, the curing processes of UPRs could be well described by the Sesták–Berggren autocatalytic model. Full article

(This article belongs to the Special Issue Study and Applications of Resins in Civil Engineering)

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12 pages, 3530 KiB

Open AccessArticle

Estimation of Synthetic Rubber Lifespan Based on Ozone Accelerated Aging Tests

by Jeongnam Kim, Youngki Kim and Youhee Cho

Polymers 2025, 17(6), 819; https://doi.org/10.3390/polym17060819 - 20 Mar 2025

Viewed by 244

Abstract

This study investigates the impact of ozone exposure on the hardness of synthetic rubber specimens (a blend of NR (natural rubber) and CR (chloroprene rubber)) through accelerated aging tests. Using a linear regression model, the research predicts the lifespan of rubber under real-world [...] Read more.

This study investigates the impact of ozone exposure on the hardness of synthetic rubber specimens (a blend of NR (natural rubber) and CR (chloroprene rubber)) through accelerated aging tests. Using a linear regression model, the research predicts the lifespan of rubber under real-world conditions and demonstrates how established experimental methods can yield novel insights when applied to synthetic rubber. The results show that ozone exposure significantly increases hardness within the first 10 days, stabilizing after day 12. Through analysis, this study calculates acceleration factors based on ozone concentration and temperature, estimating the practical lifespan of synthetic rubber under actual conditions to be approximately 25.76 years. These findings provide valuable indicators for evaluating the durability of synthetic rubber materials and predicting the longevity of rubber products in industrial applications. Furthermore, the research emphasizes the potential for improving lifespan prediction accuracy by incorporating non-linear models or machine learning approaches. Full article

(This article belongs to the Special Issue Polymer Physics: From Theory to Experimental Applications: 2nd Edition)

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24 pages, 5015 KiB

Open AccessArticle

Polymeric Nanocomposites of Polyvinyl Alcohol Embedded with ZnO/CuO/Single-Walled Carbon Nanotubes: Optical and Radiation Shielding Investigations

by Sami S. Alharthi and Ali Badawi

Polymers 2025, 17(6), 818; https://doi.org/10.3390/polym17060818 - 20 Mar 2025

Cited by 1 | Viewed by 298

Abstract

The optical and radiation shielding of PVA have been enhanced through embedding with ZnO/CuO/SWCNT (ZCS) nanocomposites. ZCS polymeric nanocomposites (PNCs) were prepared with the solution casting method. Scanning electron, optical microscopy and FT-IR procedures were performed to examine the surfaces’ morphology and structures’ [...] Read more.

The optical and radiation shielding of PVA have been enhanced through embedding with ZnO/CuO/SWCNT (ZCS) nanocomposites. ZCS polymeric nanocomposites (PNCs) were prepared with the solution casting method. Scanning electron, optical microscopy and FT-IR procedures were performed to examine the surfaces’ morphology and structures’ modifications. UV–visible measurements were carried out to investigate the linear/nonlinear optical properties. The optical investigations show significant alterations in the optical parameters of PVA due to ZCS embedding. The UV–visible analysis shows that the optical parameters, including the transmittance, energy bandgap, refractive index, dielectric constants and optical conductivity of PVA, are tuned through ZCS embedding. The direct and indirect bandgap of PVA shrank from 5.42 eV and 4.99 eV (neat PVA) to 3.20 eV and 2.26 eV (10 wt.% ZCS PNCs). The nonlinear optical (NLO) constants (first order susceptibility (χ⁽¹⁾), third susceptibility (χ⁽³⁾) and refractive index (n₂)) of PVA were improved. Phy-X/PSD software was used to investigate the radiation shielding parameters of all samples. The linear attenuation coefficient (LAC), mean free path (MFP), half value layer (HVL), tenth value layer (TVL) and effective atomic number (Z_eff) of PVA were enhanced through ZCS embedding. It is found that the mass attenuation coefficient (MAC) of the neat PVA increased from 1.14 cm²/g to 7.96 cm²/g at 0.015 MeV. The HVL of PVA decreased from 30.2 cm to 20.6 cm, the TVL decreased from 100.3 cm to 68.5 cm and the MFP decreased from 43.6 cm to 29.8 cm upon embedding 10 wt.% of ZCS NCs at 15 MeV. The samples’ exposure buildup factor (EBF) and energy absorption buildup factor (EABF) in the photon energy range from 0.015 MeV to 15 MeV at 0.5 to 40 MFP values. This study proves that ZCS PNCs are advantageous for applications in optical and radiation shielding fields. Full article

(This article belongs to the Section Polymer Analysis and Characterization)

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17 pages, 4946 KiB

Open AccessArticle

Enhanced Carbon Nanotube Ionogels for High-Performance Wireless Strain Sensing

by Xiao Wang, Menglin Tian, Jiajia Wan, Shuxing Mei, Mingwang Pan and Zhicheng Pan

Polymers 2025, 17(6), 817; https://doi.org/10.3390/polym17060817 - 20 Mar 2025

Viewed by 278

Abstract

Ionogels, as emerging stretchable conductor materials, have garnered significant attention for their potential applications in flexible electronics, particularly in wearable strain sensors. However, a persistent challenge in optimizing ionogels lies in achieving a balance between enhanced mechanical properties and electrical conductivity. In this [...] Read more.

Ionogels, as emerging stretchable conductor materials, have garnered significant attention for their potential applications in flexible electronics, particularly in wearable strain sensors. However, a persistent challenge in optimizing ionogels lies in achieving a balance between enhanced mechanical properties and electrical conductivity. In this study, we successfully addressed this challenge by incorporating carbon nanotubes (CNTs) into ionogels, achieving a simultaneous improvement in the electrical conductivity (2.67 mS/cm) and mechanical properties (400.83 kPa). The CNTs served dual purposes, acting as a continuous conductive pathway to facilitate electrical signal transmission and as reinforcing nanotubes to bolster the mechanical robustness of the ionogels. Additionally, the polymer network, composed of acrylic acid (AA) and 2-hydroxyethyl acrylate (HEA), established a purely physical cross-linking network characterized by dense hydrogen bonding, which ensured sufficient toughness within the ionogels. Notably, the assembled ionogels, when utilized as wireless strain sensors, demonstrated exceptional sensitivity in detecting subtle finger movements, with the CNTs significantly amplifying the electrical response. This work provides new insights into the integration of carbon nanotubes in ionogels, expanding their applications and pioneering a fresh approach to functionalized ionogel design. Full article

(This article belongs to the Section Polymer Applications)

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14 pages, 2626 KiB

Open AccessArticle

Fluorescent Molecular Imprinted Sensor Based on Carbon Quantum Dot for Nitrofen Detection in Water Sample

by Yuge Chen, Yongheng Zhou, Jinjie You, Zeming Zhang, Aili Sun, Hua Liu and Xizhi Shi

Polymers 2025, 17(6), 816; https://doi.org/10.3390/polym17060816 - 20 Mar 2025

Viewed by 253

Abstract

The structure of nitrofen is stable and resistant to natural degradation, persisting in environments for extended periods. It can accumulate through the food chain, posing risks to human health. Here, we report a sensor based on carbon quantum dots (CQDs) and molecular imprinting [...] Read more.

The structure of nitrofen is stable and resistant to natural degradation, persisting in environments for extended periods. It can accumulate through the food chain, posing risks to human health. Here, we report a sensor based on carbon quantum dots (CQDs) and molecular imprinting technology (CQDs@MIPs). It not only possesses the specificity and stability of MIPs but also incorporates the environmental friendliness and signal amplification capabilities of CQDs, making it an ideal material for the specific detection of nitrofen residues in the environment. The interaction between CQDs@MIPs and nitrofen, as well as the successful removal of nitrofen, were confirmed through transmission electron microscopy (TEM) and Zeta potential analysis, which evaluated the morphology and particle size of the prepared CQDs@MIPs. After binding with nitrofen, the CQDs@MIP sensor exhibited a low detection limit (2.5 × 10⁻³ mg·L⁻¹), a wide detection range (0.01–40 mg·L⁻¹), a good linear relationship (R² = 0.9951), and a short detection time (5 min). The CQDs@MIP sensor also demonstrated excellent stability, with the fluorescence intensity of CQDs@MIPs remaining above 90% of the initial preparation after 20 days. At the same time, Red, Green, Blue (RGB) color model extraction technology is used to fit the color of the sample under different concentrations, and the smart phone application is integrated to realize the visual detection of nitrofen. Furthermore, acceptable accuracy was achieved in real water samples (recovery rates ranging from 84.1% to 115.7%), indicating that our CQDs@MIP sensor has high analytical potential for real samples. Full article

(This article belongs to the Special Issue Research and Application of Molecularly Imprinted Polymers)

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19 pages, 1663 KiB

Open AccessArticle

Specimen Size and Environmental Exposure Effects on Initial Diffusion in E-Glass/Vinylester Pultruded Composites

by Vistasp M. Karbhari

Polymers 2025, 17(6), 815; https://doi.org/10.3390/polym17060815 - 20 Mar 2025

Viewed by 220

Abstract

This paper studies the effect of specimen size on the moisture uptake characteristics of pultruded E-glass/vinylester composites exposed to conditions of immersion and 99% RH over a range of temperatures. Four different specimen sizes representative of sizes commonly used for material characterization (tension, [...] Read more.

This paper studies the effect of specimen size on the moisture uptake characteristics of pultruded E-glass/vinylester composites exposed to conditions of immersion and 99% RH over a range of temperatures. Four different specimen sizes representative of sizes commonly used for material characterization (tension, short-beam-shear, and dynamic mechanical thermal analysis) as well as moisture uptake are included. It is shown that both exposure conditions and geometry significantly influence uptake behavior, and that the differences, in general, can be elucidated through consideration of surface-to-edge area ratios of the specimens. For the current study, the ratio extends from 2.528 at the lowest level for the short-beam-shear specimens to 16.979 at the highest for the tensile specimens. The overall levels of uptake in the period of exposure, the levels of transition uptake, and the diffusion coefficients are noted to increase with a decrease in the ratio, suggesting an increased influence of the edge effect, which is further enhanced with an increase in temperature. Levels of normalized transition uptake for the specimens with the lowest surface-to-edge area ratio are 12.5 and 8.2 times higher than those for the specimens with the highest ratio at the two extreme temperatures, respectively, when exposed to 99% RH, and are 7.2 and 15.3 times, respectively, under conditions of immersion. Activation energy calculations also highlight differences based on specimen size and the condition of exposure with immersion leading to a lower activation energy than exposure to 99% RH when considering the initial linear regime with the specimens having the largest surface-to-edge area ratios showing 11.3–13.5% higher levels due to exposure to 99% RH, whereas the two specimens with the smaller ratios show a 4.9% increase. The findings highlight the importance of specimen size and exposure conditions and emphasize that the commonly used assumptions could lead to inaccurate results especially when extrapolated. The use of the immersion condition as a means of accelerating field conditions of humidity could significantly overestimate effects. Further, the direct use of uptake characteristics from specimens at one size, or surface-to-edge area ratio, could lead to inaccurate conclusions if extrapolated to specimens that are significantly different leading to design and durability prediction implications. Full article

(This article belongs to the Section Polymer Composites and Nanocomposites)

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21 pages, 5574 KiB

Open AccessArticle

Pectin/Gellan Gum Hydrogels Loaded with Crocus sativus Tepal Extract for In Situ Modulation of Pro-Inflammatory Pathways Affecting Wound Healing

by Francesco Busto, Caterina Licini, Stefania Cometa, Stefano Liotino, Elisabetta Damiani, Tiziana Bacchetti, Isabelle Kleider, Alessandra La Contana, Monica Mattioli-Belmonte and Elvira De Giglio

Polymers 2025, 17(6), 814; https://doi.org/10.3390/polym17060814 - 20 Mar 2025

Viewed by 305

Abstract

Tepals of the Crocus sativus flower constitute the most abundant floral residue during saffron production (350 kg tepals/kg stigmas). Being a natural source of polyphenols with antioxidant properties, they can be reused to create potentially valuable products for pharmaceutical applications, generating a new [...] Read more.

Tepals of the Crocus sativus flower constitute the most abundant floral residue during saffron production (350 kg tepals/kg stigmas). Being a natural source of polyphenols with antioxidant properties, they can be reused to create potentially valuable products for pharmaceutical applications, generating a new income source while reducing agricultural bio-waste. In this work, composite hydrogels based on blends of pectin and gellan gum containing Crocus sativus tepal extract (CSE) have been proposed for the regeneration and healing of cutaneous wounds, exploiting the antioxidant properties of CSE. Various physico-chemical and mechanical characterizations were performed. The skin permeation of CSE was investigated using Franz cell diffusion system. The composite films were cytocompatible and able to counteract the increase in ROS, restore the production of matrix proteins, and favor wound closure. To conclude, CSE-loaded composite films represent a promising strategy to promote the body’s natural healing process. In addition, by reusing saffron tepals, not only can we develop new, sustainable treatments for skin diseases, but we can also reduce agricultural waste. Full article

(This article belongs to the Special Issue Innovations in Hydrogel Design for Pharmaceutical and Medical Applications)

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15 pages, 8383 KiB

Open AccessArticle

Biodegradable Electret Filters Based on Beeswax-Modified Fibers: A Novel Production Strategy

by Agata Penconek, Łukasz Werner, Zuzanna Bojarska and Arkadiusz Moskal

Polymers 2025, 17(6), 813; https://doi.org/10.3390/polym17060813 - 20 Mar 2025

Viewed by 272

Abstract

This research aims to create a high-efficiency, low-resistance biodegradable air-filter structure containing beeswax as a result of the simultaneous production of fibers by solution-blowing and melt-blowing. The melt-blowing method is effective for producing micrometer fibers on an industrial scale. In turn, the solution-blowing [...] Read more.

This research aims to create a high-efficiency, low-resistance biodegradable air-filter structure containing beeswax as a result of the simultaneous production of fibers by solution-blowing and melt-blowing. The melt-blowing method is effective for producing micrometer fibers on an industrial scale. In turn, the solution-blowing method allows for the production of fibers with a nanometric diameter from solutions containing temperature-sensitive additives such as beeswax. Combining these two methods is a promising perspective for producing high-performance, functional air-filter materials. Beeswax is a natural material capable of accumulating an electrical charge. When an external electric field is applied, the presence of beeswax in the filter structure facilitates charge retention on the fiber surface. This results in a fully biodegradable filter material with high efficiency and low resistance. Full article

(This article belongs to the Special Issue New Polymer Fibers: Production and Applications)

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14 pages, 2266 KiB

Open AccessArticle

Performance Properties of Epoxy Resin Modified with Few-Layer Graphene Obtained by the Method of Self-Propagating High-Temperature Synthesis

by Nikita Podlozhnyuk, Aleksei Vozniakovskii, Sergey Kidalov and Alexander Voznyakovskii

Polymers 2025, 17(6), 812; https://doi.org/10.3390/polym17060812 - 20 Mar 2025

Viewed by 272

Abstract

This study presents the results of an investigation into the influence of few-layer graphene, produced by self-propagating high-temperature synthesis from various types of biopolymers (glucose, cellulose, and lignin), on the mechanical, thermophysical, and tribological properties of epoxy resin. It was found that the [...] Read more.

This study presents the results of an investigation into the influence of few-layer graphene, produced by self-propagating high-temperature synthesis from various types of biopolymers (glucose, cellulose, and lignin), on the mechanical, thermophysical, and tribological properties of epoxy resin. It was found that the addition of few-layer graphene at concentrations of up to 1 wt.% leads to an increase in compressive strength by up to 40%, flexural strength by up to 15%, and thermal conductivity by up to 40% compared to the original resin. A fivefold increase in the wear resistance of the composites was also observed compared to pure epoxy resin, due to a reduction in the friction coefficient. Full article

(This article belongs to the Special Issue Advances in Thermal, Electrical and Mechanical Properties of Polymer Composites)

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19 pages, 6256 KiB

Open AccessArticle

Ultraviolet-Follow Curing-Mediated Extrusion Stabilization for Low-Yield-Stress Silicone Rubbers: From Die Swell Suppression to Dimensional Accuracy Enhancement

by Bing Liu and Baoji Ma

Polymers 2025, 17(6), 811; https://doi.org/10.3390/polym17060811 - 19 Mar 2025

Viewed by 271

Abstract

Direct ink writing (DIW) of low-yield-stress UV-curable silicone rubber faces challenges in maintaining dimensional accuracy due to post-extrusion swelling and viscoelastic deformation. This study proposes an ultraviolet-follow curing (UFC) method to enhance geometric precision by UV-follow curing (UFC) during deposition. The effects of [...] Read more.

Direct ink writing (DIW) of low-yield-stress UV-curable silicone rubber faces challenges in maintaining dimensional accuracy due to post-extrusion swelling and viscoelastic deformation. This study proposes an ultraviolet-follow curing (UFC) method to enhance geometric precision by UV-follow curing (UFC) during deposition. The effects of UFC on filament dimensions—including width, length, cross-sectional geometry, and roundness—were systematically investigated. The mechanical properties of the printed structures were also evaluated to assess their functional integrity. The experimental results demonstrated that UFC effectively reduced extrusion swelling, achieving a filament-width deviation reduction of 22–81% and a filament-length deviation of 1.4–1.8% compared to conventional DIW. The printed rings exhibited improved roundness uniformity with reduced geometric fluctuations. Crucially, UFC enhances dimensional accuracy without compromising the mechanical performance of low-yield-stress silicones, providing a viable strategy for the high-precision additive manufacturing of soft elastomeric architectures. Full article

(This article belongs to the Section Polymer Processing and Engineering)

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21 pages, 3023 KiB

Open AccessArticle

Bioengineering the Future: Tomato Peel Cutin as a Resource for Medical Textiles

by Gianni Pecorini, Martina Tamburriello, Erika Maria Tottoli, Ida Genta, Bice Conti, Maria Nelly Garcia Gonzalez, Rita Nasti and Rossella Dorati

Polymers 2025, 17(6), 810; https://doi.org/10.3390/polym17060810 - 19 Mar 2025

Viewed by 352

Abstract

The exponential increase in medical waste production has increased the difficulty of waste management, resulting in higher medical waste dispersion into the environment. By employing a circular economy approach, it is possible to develop new materials by waste valorization. The employment of biodegradable [...] Read more.

The exponential increase in medical waste production has increased the difficulty of waste management, resulting in higher medical waste dispersion into the environment. By employing a circular economy approach, it is possible to develop new materials by waste valorization. The employment of biodegradable and renewable agro-food, waste-derived materials may reduce the environmental impact caused by the dispersion of medical waste. In this work, tomato peel recovered cutin was blended with poly(L-lactide-co-ε-caprolactone) (PLAPCL) to develop new textiles for medical application through electrospinning. The textile fabrication process was studied by varying Cut content in the starting suspensions and by optimizing fabrication parameters. Devices with dense and porous structures were developed, and their morphological, thermal, and physical–chemical properties were evaluated through scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and Fourier transformed infrared spectroscopy. Textile material stability to γ-irradiation was evaluated through gel permeation chromatography, while its wettability, mechanical properties, and biocompatibility were analyzed through contact angle measurement, tensile test, and MTT assay, respectively. The LCA methodology was used to evaluate the environmental impact of textile production, with a specific focus on greenhouse gas (GHG) emissions. The main results demonstrated the suitability of PLAPCL–cutin blends to be processed through electrospinning and the obtained textile’s suitability to be used to develop surgical face masks or patches for wound healing. Full article

(This article belongs to the Special Issue Polymers: Bio-Based Medical Textile)

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17 pages, 7376 KiB

Open AccessArticle

The Effect of Polysaccharide Colloids on the Thermal Stability of Water-in-Oil Emulsions

by Shunfa Zhao, Ran Wang, Ying Xu, Caiyun Wang, Jun Xu, Pengjie Wang, Yonggang Fu, Jiaqi Su, Hanyu Chai, Jian He and Han Chen

Polymers 2025, 17(6), 809; https://doi.org/10.3390/polym17060809 - 19 Mar 2025

Viewed by 252

Abstract

The preference and demand for low-fat diets have increased due to their health benefits. This study aimed to develop a thermally stable water-in-oil (W/O) emulsion. The addition of 3.75 wt% of polysaccharide colloids, including curdlan gum (CG), kappa-carrageenan (kC), gellan gum (GEG), guar [...] Read more.

The preference and demand for low-fat diets have increased due to their health benefits. This study aimed to develop a thermally stable water-in-oil (W/O) emulsion. The addition of 3.75 wt% of polysaccharide colloids, including curdlan gum (CG), kappa-carrageenan (kC), gellan gum (GEG), guar gum (GUG), high-ester pectin (HEP), and carboxymethyl cellulose (CMC), to the aqueous phase resulted in the formation of a gel structure within it. Furthermore, these polysaccharide colloids reduced the excessive mobility of water droplets under high-temperature conditions. The oil phase consisted of anhydrous butter and a lipophilic nonionic surfactant. The emulsion was subjected to a heat treatment at 95 °C for 30 min, and the emulsions before and after the heat treatment were characterized. The results showed that among the above colloidal emulsions, the 3.75 wt% CG emulsion did not show significant changes in viscosity, stability index, mean particle size, friction coefficient, and encapsulation efficiency before and after heat treatment. The 3.75 wt% CG colloid showed the most significant enhancement in the thermal stability of W/O emulsions. This study proposes a novel fat-replacement strategy for products requiring high-temperature processing, such as processed cheese. Full article

(This article belongs to the Special Issue Natural Polysaccharide: Synthesis, Modification and Application (2nd Edition))

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12 pages, 2945 KiB

Open AccessArticle

UV-Assisted Material Extrusion Additive Manufacturing of Double-Base Propellant

by Manman Li, Yuchen Gao, Qionglin Wang, Weitao Yang, Guo-Lin Gao and Zaixing Jiang

Polymers 2025, 17(6), 808; https://doi.org/10.3390/polym17060808 - 19 Mar 2025

Viewed by 219

Abstract

Double-base (DB) propellants, renowned for their superior performance and cost-effectiveness, are extensively utilized in both rocketry and artillery applications. During the 3D printing process of double-base propellants, auxiliary solvents play a crucial role in plasticizing the DB propellant mixtures. Consequently, the printed propellants [...] Read more.

Double-base (DB) propellants, renowned for their superior performance and cost-effectiveness, are extensively utilized in both rocketry and artillery applications. During the 3D printing process of double-base propellants, auxiliary solvents play a crucial role in plasticizing the DB propellant mixtures. Consequently, the printed propellants are prone to significant shrinkage and dimensional instability as a result of solvent evaporation post-printing. To address these challenges, we have innovated a UV-assisted material extrusion 3D printing technique that preserves the intended geometries of the DB propellant. The results of our printing trials indicate that incorporating an energetic UV-curable resin as a modifier into the DB propellant paste is highly effective. Ultimately, we successfully fabricated a porous propellant cylinder featuring a periodic woodpile structure. Additionally, the internal structure, mechanical properties, combustion characteristics, and in-barrel ballistic performance of the printed propellants have been thoroughly characterized. Our findings underscore that the UV-assisted material extrusion additive manufacturing process confers exceptional properties to the DB propellant. Full article

(This article belongs to the Section Polymer Processing and Engineering)

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25 pages, 12526 KiB

Open AccessArticle

Innovative Approaches to RC Deep Beam Strengthening: Evaluating Low-Cost Glass Fiber Wraps Against Traditional CFRP Solutions

by Panumas Saingam, Ali Ejaz, Chaitanya Krishna Gadagamma, Qudeer Hussain, Gritsada Sua-iam, Burachat Chatveera, Bodee Maneengamlert and Panuwat Joyklad

Polymers 2025, 17(6), 807; https://doi.org/10.3390/polym17060807 - 19 Mar 2025

Viewed by 320

Abstract

This study evaluates the performance of lightweight aggregate deep beams strengthened with low-cost glass fiber-reinforced polymer composite (Lo-G) wraps as an alternative to expensive synthetic fiber-reinforced polymers (FRPs). The investigation includes side-bonded and fully wrapped configurations of Lo-G wraps, alongside carbon FRP (CFRP) [...] Read more.

This study evaluates the performance of lightweight aggregate deep beams strengthened with low-cost glass fiber-reinforced polymer composite (Lo-G) wraps as an alternative to expensive synthetic fiber-reinforced polymers (FRPs). The investigation includes side-bonded and fully wrapped configurations of Lo-G wraps, alongside carbon FRP (CFRP) strips for comparison. The experimental results show that epoxy-based anchors provided significantly better resistance against de-bonding than mechanical anchors, improving beam performance. Strengthening with Lo-G wraps resulted in a peak capacity increase of 17.0% to 46.9% for side-bonded beams in Group 2, 10.5% to 41.4% for fully wrapped beams in the strip configuration in Group 3, and 15.4% to 42.7% for CFRP strips in Group 4. The ultimate deflection and dissipated energy were also improved, with dissipated energy increases of up to 264.6%, 322.3%, and 222.7% for side-bonded and fully wrapped Lo-G wraps and CFRP strips, respectively. The side-bonded configuration with two or three Lo-G wraps, supplemented by epoxy wraps, outperformed fully wrapped 250 mm strips in peak capacity, with peak capacity improvements of up to 46.9%. However, beams with mechanical anchors showed poor performance due to premature debonding. They rely on friction and expansion within the concrete to resist pull-out forces. If the surrounding concrete is not strong enough or if the anchor is not properly installed, it can lead to failure. Additionally, reducing strip spacing negatively impacted performance. Lo-G wraps showed an 8.5% higher peak capacity and 32.8% greater dissipated energy compared to CFRP strips. Despite these improvements, while Lo-G wraps are a cost-effective alternative, their long-term performance remains to be investigated. None of the existing models accurately predicted the shear strength contribution of Lo-G wraps, as the lower elastic modulus and tensile strength led to high deviations in prediction-to-experimental ratios, underscoring the need for new models to assess shear strength. Full article

(This article belongs to the Special Issue New Insights into Fiber-Reinforced Polymer Composites)

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17 pages, 7330 KiB

Open AccessArticle

Exploring the Feasibility of Deep Learning for Predicting Lignin GC-MS Analysis Results Using TGA and FT-IR

by Mingyu Park, Byung Hwan Um, Seung-Hyun Park and Dae-Yeol Kim

Polymers 2025, 17(6), 806; https://doi.org/10.3390/polym17060806 - 18 Mar 2025

Viewed by 393

Abstract

Lignin is a complex biopolymer extracted from plant cell walls, playing a crucial role in structural integrity. As the second most abundant biopolymer after cellulose, lignin has significant industrial value in bioenergy, the chemical industry, and agriculture, gaining attention as a sustainable alternative [...] Read more.

Lignin is a complex biopolymer extracted from plant cell walls, playing a crucial role in structural integrity. As the second most abundant biopolymer after cellulose, lignin has significant industrial value in bioenergy, the chemical industry, and agriculture, gaining attention as a sustainable alternative to fossil fuels. Its composition changes during degradation, affecting its applications, making accurate analysis essential. Common lignin analysis methods include Thermogravimetric Analysis (TGA), Fourier-transform Infrared Spectroscopy (FT-IR), and Gas Chromatography–Mass Spectrometry (GC-MS). While GC-MS enables precise chemical identification, its high cost and time requirements limit frequent use in budget-constrained studies. To address this challenge, this study explores the feasibility of an artificial intelligence model that predicts the GC-MS analysis results of depolymerized lignin using data obtained from TGA and FT-IR analyses. The proposed model demonstrates potential but requires further validation across various lignin substrates for generalizability. Additionally, collaboration with organic chemists is essential to assess its practical applicability in real-world lignin and biomass research. Full article

(This article belongs to the Special Issue Lignin Isolation, Characterization and Application)

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12 pages, 3395 KiB

Open AccessArticle

Evaluation of Selected Fire Properties of Recycled Particleboards

by Zuzana Vidholdová, Martin Zachar, Ján Iždinský and Viktória Satinová

Polymers 2025, 17(6), 805; https://doi.org/10.3390/polym17060805 - 18 Mar 2025

Viewed by 215

Abstract

This study evaluated the fire properties of various particleboard (PB) types, including those made from sound spruce particles, degraded wood (brown and white rot), and recycled materials (blockboard, pallets, thermally modified wood, raw and laminated PBs, or mixtures). Laboratory-manufactured PBs showed densities ranging [...] Read more.

This study evaluated the fire properties of various particleboard (PB) types, including those made from sound spruce particles, degraded wood (brown and white rot), and recycled materials (blockboard, pallets, thermally modified wood, raw and laminated PBs, or mixtures). Laboratory-manufactured PBs showed densities ranging from 587 to 654 kg·m⁻³, with higher densities generally correlating with longer ignition times, although no statistically significant relationship was observed. Ignition times varied depending on material composition, with PBs made from sound spruce particles exhibiting the longest ignition times (103 ± 4.89 s). In contrast, PBs containing recycled or degraded particles ignited faster, influenced by additives such as adhesives and laminates. The burning rate peaked between 90 and 180 s, with PBs containing recycled raw PB particles and those degraded by brown rot showing the highest maximum burning rates (0.214 and 0.213 %·s⁻¹, respectively). Recycled laminated PBs reached peak burning rates in the shortest time, while control PBs required the longest time. Mass loss was higher in PBs with recycled or degraded particles, ranging from 47.52% to 51.71%, compared to 44.89% for control PBs. These findings highlight the trade-offs between fire resistance and the use of recycled materials, emphasizing the impact of additives on combustion behavior. Full article

(This article belongs to the Special Issue Wood and Wood-Based Composites: New Frontiers in Modification, Performance, and Sustainability)

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18 pages, 5509 KiB

Open AccessArticle

Enhancing Mechanical and Impact Properties of Flax/Glass and Jute/Glass Hybrid Composites Through KOH Alkaline Treatment

by Sultan Ullah, Arvydas Palevicius, Giedrius Janusas and Zeeshan Ul-Hasan

Polymers 2025, 17(6), 804; https://doi.org/10.3390/polym17060804 - 18 Mar 2025

Viewed by 259

Abstract

This research investigates the influence of potassium hydroxide (KOH) treatment on the mechanical, flexural, and impact properties of flax/glass and jute/glass hybrid composites. Hybrid composite materials have been developed, incorporating natural fibers that are both treated and untreated by KOH, with glass fiber [...] Read more.

This research investigates the influence of potassium hydroxide (KOH) treatment on the mechanical, flexural, and impact properties of flax/glass and jute/glass hybrid composites. Hybrid composite materials have been developed, incorporating natural fibers that are both treated and untreated by KOH, with glass fiber within an epoxy matrix. Natural fibers, such as flax and jute, were chemically treated using different KOH concentrations and immersion times specific to each fiber type. Following the treatment, both fibers were rinsed with distilled water and subsequently dried. The natural fiber’s chemical interaction was analysed using FTIR. Hybrid composites were fabricated via the integration of intercalated layers of natural fibers and glass fiber using hand layup followed by compression molding. Mechanical properties, including impact resistance, flexural strength, elastic modulus, and tensile strength, were evaluated in accordance with ASTM guidelines. KOH-treated flax/glass composites (T-F2G2) demonstrated enhanced fiber–matrix bonding, indicated by elevated tensile strength (118.16 MPa) and flexural strength (168.94 MPa) relative to untreated samples. The impact strength of T-F2G2 composites increased to 39.33 KJ/m² due to the removal of impurities and exposure of hydroxyl groups, which interact with K⁺ ions in KOH, thereby improving their mechanical properties. SEM analysis of cracked surfaces confirmed enhanced bonding and reduced fiber pull-out, indicating improved interfacial compatibility. The findings demonstrate that KOH treatment effectively preserves cellulose integrity and enhances fiber–matrix interactions, positioning it as a viable alternative to NaOH for hybrid composites suitable for lightweight and environmentally sustainable industrial applications. Full article

(This article belongs to the Special Issue Damping Mechanisms in Polymers and Polymer Composites)

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24 pages, 6184 KiB

Open AccessArticle

Integration of Complexed Caffeic Acid into Poly(Lactic Acid)-Based Biopolymer Blends by Supercritical CO₂-Assisted Impregnation and Foaming: Processing, Structural and Thermal Characterization

by Patricia Rivera, Alejandra Torres, Miguel Pacheco, Julio Romero, Marina P. Arrieta, Francisco Rodríguez-Mercado and Julio Bruna

Polymers 2025, 17(6), 803; https://doi.org/10.3390/polym17060803 - 18 Mar 2025

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Abstract

Conventional techniques for incorporating active ingredients into polymeric matrices are accompanied by certain disadvantages, primarily attributable to the inherent characteristics of the active ingredient itself, including its sensitivity to temperature. A potential solution to these challenges lies in the utilization of supercritical carbon [...] Read more.

Conventional techniques for incorporating active ingredients into polymeric matrices are accompanied by certain disadvantages, primarily attributable to the inherent characteristics of the active ingredient itself, including its sensitivity to temperature. A potential solution to these challenges lies in the utilization of supercritical carbon dioxide (scCO₂) for the formation of polymeric foam and the incorporation of active ingredients, in conjunction with the encapsulation of inclusion complexes (ICs), to ensure physical stability and augmented bioactivity. The objective of this study was to assess the impact of IC impregnation and subsequent foam formation on PLA films and PLA/PBAT blends that had been previously impregnated. The study’s methodology encompassed the formation and characterization of ICs with caffeic acid (CA) and β-cyclodextrin (β-CD), along with the thermal, structural, and morphological properties of the resulting materials. Higher incorporation of impregnated IC into the PLA(42)/PBAT(58) blend was observed at 12 MPa pressure and a depressurization rate of 1 MPa/min. The presence of IC, in addition to a lower rate of expansion, contributed to the formation of homogeneous cells with a size range of 4–44 um. On the other hand, the incorporation of IC caused a decrease in the crystallinity of the PLA fraction due to the interaction of the complex with the polymer. This study makes a significant contribution to the advancement of knowledge on the incorporation of compounds encapsulated in β-CD by scCO₂, as well as to the development of active materials with potential applications in food packaging. Full article

(This article belongs to the Special Issue Multifunctional Polymeric Formulations for Sustainable Food Packaging Applications, 2nd Edition)

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15 pages, 7965 KiB

Open AccessArticle

High-Temperature Compressive Properties of 3D Printed Polymeric Lattice-Reinforced Cement-Based Materials

by Yawen Gu, Jing Qiao, Junwei Liu, Wenfeng Hao and Can Tang

Polymers 2025, 17(6), 802; https://doi.org/10.3390/polym17060802 - 18 Mar 2025

Viewed by 237

Abstract

Currently, research has confirmed the significant potential of 3D printed polymer lattices in enhancing the mechanical properties of cement-based composites. Polymer materials are influenced by high-temperature environments. This study aims to further explore the impact of 3D printed lattice structures on the compressive [...] Read more.

Currently, research has confirmed the significant potential of 3D printed polymer lattices in enhancing the mechanical properties of cement-based composites. Polymer materials are influenced by high-temperature environments. This study aims to further explore the impact of 3D printed lattice structures on the compressive mechanical properties of cement-based materials under high-temperature conditions. The approach employed in this paper involves utilizing the multiple jet fusion (MJF) technique to fabricate two types of lattices with the same volume fraction within cement-based samples. Uniaxial compression experiments were carried out on cement-based samples both with and without the 3D printed lattice at room temperature, 50 °C, and 100 °C. The research explores the compressive properties of cement-based samples reinforced with different lattice structures at varying ambient temperatures. Additionally, digital image correlation (DIC) technology was utilized to analyze the deformation characteristics of the samples. The experimental results demonstrate that the 3D printed lattice effectively enhances the compressive properties of cement-based materials. However, it is worth noting that the cement-based samples reinforced with this material exhibit higher temperature sensitivity compared to the lattice-free reinforced samples. Full article

(This article belongs to the Special Issue Advanced Experimental Mechanics in Polymer Composites Testing)

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14 pages, 2725 KiB

Open AccessArticle

Enhancing the Physicochemical, Thermal, and Technological Properties of Freeze-Dried Welsh Onion Leaf Juice: Influence of Maltodextrin and Gum Arabic as Carrier Agents

by Carolina Medina-Jaramillo and Alex López-Córdoba

Polymers 2025, 17(6), 801; https://doi.org/10.3390/polym17060801 - 18 Mar 2025

Viewed by 225

Abstract

Fresh Welsh onions are widely used in food formulations due to their distinctive flavor and biological properties, but their high perishability limits their industrial applications. In this study, powdered Welsh onion leaf juices were obtained through freeze-drying, with and without maltodextrin (MD) and [...] Read more.

Fresh Welsh onions are widely used in food formulations due to their distinctive flavor and biological properties, but their high perishability limits their industrial applications. In this study, powdered Welsh onion leaf juices were obtained through freeze-drying, with and without maltodextrin (MD) and gum arabic (GA) as carrier agents. MD was chosen for its high solubility and neutral taste, while GA was selected for its ability to improve powder stability and dispersibility. Powders were obtained using a completely randomized design to evaluate the effects of five MD:GA ratios (0:100, 25:75, 50:50, 75:25, and 100:0) on their physicochemical and technological properties. The addition of carriers enabled the formation of fine, homogeneous powders with higher water solubility. All formulations exhibited low water activity (<0.4) and moisture content (<7%). Polyphenol content ranged from 2.60 to 3.53 mg GAE/g of dry matter, with a high recovery percentage (94–96%). DPPH^• scavenging activity was about 0.55 mg GAE/g of dry matter for all powders with carrier agents. Fourier-transform infrared (FTIR) analysis confirmed the presence of characteristic bands from both the carrier agents and the onion leaf juice, while thermogravimetric analysis (TGA) revealed enhanced thermal stability with carrier agents. Flowability tests showed that MD and MD:GA blends significantly improved powder handling. Full article

(This article belongs to the Special Issue Advances in Polymer Materials and Food Science)

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25 pages, 12594 KiB

Open AccessArticle

Enhancing the Flexibility and Hydrophilicity of PLA via Polymer Blends: Electrospinning vs. Solvent Casting

by Qi-Hong Weng, Ming-Hsien Hu, Ji-Feng Wang and Jin-Jia Hu

Polymers 2025, 17(6), 800; https://doi.org/10.3390/polym17060800 - 18 Mar 2025

Viewed by 382

Abstract

Polylactic acid (PLA) is a biodegradable polymer with high tensile strength, high stiffness, and biocompatibility, but its brittleness and hydrophobicity limit its applications. This study aims to address these limitations by blending PLA with polycaprolactone (PCL) to enhance flexibility and with polyethylene oxide [...] Read more.

Polylactic acid (PLA) is a biodegradable polymer with high tensile strength, high stiffness, and biocompatibility, but its brittleness and hydrophobicity limit its applications. This study aims to address these limitations by blending PLA with polycaprolactone (PCL) to enhance flexibility and with polyethylene oxide (PEO) to improve hydrophilicity. Unlike conventional approaches where PEO serves as a plasticizer, this study investigated PEO as a major blend component. Electrospinning and solvent casting, which differ in their solvent evaporation rates, were employed to fabricate thin films of neat PLA and PLA blends to examine their influence on mechanical and surface properties. Polymer solutions were prepared using a dichloromethane (DCM)/dimethylformamide (DMF) mixture known to enhance the electrospinning process. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were used to investigate crystallinity of polymers and their interactions, while scanning electron microscopy (SEM) and atomic force microscopy (AFM) provided insights into phase separation and fiber morphology. Uniaxial tensile testing and water contact angle measurements were conducted to evaluate mechanical properties and surface properties, respectively. The results showed that electrospun PLA films exhibited higher elongation at break and ultimate strength but lower Young’s modulus than solvent-cast PLA films. Electrospun films of PLA/PCL blends demonstrated improved elongation at break while retaining Young’s modulus comparable to that of electrospun PLA films, unlike their solvent-cast counterparts. In contrast, PLA/PEO blends exhibited enhanced hydrophilicity in both processing methods but showed a marked reduction in mechanical properties. In summary, electrospun films consistently outperformed solvent-cast films in terms of flexibility and mechanical integrity, primarily due to their fibrous structure, suppressed phase separation, and reduced crystallinity. This study uniquely demonstrates that electrospinning enables the fabrication of phase-separated PLA/PEO blends with mechanical integrity despite PEO’s inherent immiscibility with PLA and incompatibility in the solvent mixture. Furthermore, electrospinning proves to be an effective processing method for producing PLA blend films with enhanced flexibility and hydrophilicity without the need for plasticizers or compatibilizers. Full article

(This article belongs to the Section Polymer Analysis and Characterization)

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17 pages, 5315 KiB

Open AccessArticle

Cl⁻, Na⁺ and Mg²⁺ Adsorption and Electronic Properties on 2-Octyl Acrylate and Isobornyl Acrylate Monomers: A Comprehensive DFT Study

by Emre Bolen, Jorge S. Dolado and Andrés Ayuela

Polymers 2025, 17(6), 799; https://doi.org/10.3390/polym17060799 - 18 Mar 2025

Viewed by 195

Abstract

The design of advanced functional materials from polymers involving 2-octyl acrylate and isobornyl acrylate monomers is crucial for applications such as biofouling resistance, coatings, UV-curable films, and use in marine environments. In this study, we investigated the adsorption and electronic properties of 2-octyl [...] Read more.

The design of advanced functional materials from polymers involving 2-octyl acrylate and isobornyl acrylate monomers is crucial for applications such as biofouling resistance, coatings, UV-curable films, and use in marine environments. In this study, we investigated the adsorption and electronic properties of 2-octyl acrylate and isobornyl acrylate monomers in the presence of Cl⁻, Na⁺, and Mg²⁺ ions using Density Functional Theory calculations. Adsorption energies, quantum descriptors, and electrostatic potential maps were analyzed to elucidate ion-specific interactions with these monomers. Our findings indicate that Mg²⁺ ions exhibit the strongest interactions due to their high charge density, followed by Na⁺ and Cl⁻ ions, which show moderate and weak adsorption, respectively. Density of states analyses revealed that Mg²⁺ significantly lowers HOMO and LUMO levels, narrowing the gap and stabilizing the system, while Cl⁻ ions result in a smaller gap and weaker interactions. Electrostatic potential maps further confirmed these trends, correlating ion adsorption sites with molecular charge distributions. This study highlights the critical role of ion adsorption and its associated electronic properties and paves the way for future advancements in optimizing 2-octyl acrylate and isobornyl acrylate-based materials for applications such as coatings and use in marine environments. Full article

(This article belongs to the Section Polymer Physics and Theory)

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