Polymers

19 pages, 2512 KB

Open AccessArticle

Green Polymeric Nanocomposite (KCl/SiO₂/Xanthan/Origanum vulgare) for Multi-Scale Interfacial Stabilization and Permeability Preservation in Carbonate Petroleum Reservoirs

by Yaser Ahmadi, Mehdi Havasbeigi and David A. Wood

Polymers 2026, 18(16), 2035; https://doi.org/10.3390/polym18162035 - 21 Aug 2026

Viewed by 297

Abstract

In carbonate petroleum reservoirs, permeability impairment caused by asphaltene precipitation and deposition remains a major challenge that limits long-term productivity. This study introduces a green polymeric nanocomposite (KCl/SiO₂/Xanthan/Origanum vulgare, NCs) designed to control interfacial dynamics and preserve flow capacity [...] Read more.

In carbonate petroleum reservoirs, permeability impairment caused by asphaltene precipitation and deposition remains a major challenge that limits long-term productivity. This study introduces a green polymeric nanocomposite (KCl/SiO₂/Xanthan/Origanum vulgare, NCs) designed to control interfacial dynamics and preserve flow capacity in carbonate formations. Using a multi-technique approach—interfacial tension (IFT) analysis, atomic force microscopy (AFM), and rock-core, fluid-flooding experiments at simulated subsurface conditions—the NCs’ abilities were evaluated in terms of their potential to modify properties at fluid–fluid and fluid–rock interfaces. The NCs increased the CO₂–brine/oil IFT slope in certain pressure regions by up to 40.77%. These results indicate competitive adsorption that stabilizes interfaces. Adsorption isotherms confirmed a monolayer mechanism with a high capacity of 294.12 mg/g. AFM topographic mapping revealed order-of-magnitude changes in surface roughness (reductions in average roughness by ~75%, root-mean-square by ~83%, peak-to-valley by ~93%). These results directly link nanoscale smoothing to reduced capillary pinning. Core flooding tests demonstrated that NCs treatment decreased formation damage by up to 67.45% at 4000 psi, maintaining a high permeability ratio (k/k_i = 0.87) and preserving porosity (φ/φ_i = 0.887, representing 88.7% porosity retention). These results establish that the studied NCs coherently manipulate fluid physics in relation to molecular adsorption and macroscopic permeability. Consequently, these NCs offer a sustainable, high-performance strategy for flow assurance and formation damage control in geological and geothermal reservoirs. Full article

(This article belongs to the Special Issue Polymer Fluids in Geology and Geotechnical Engineering)

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46 pages, 24663 KB

Open AccessReview

From Screening to Optimization: Strategic Implementation of Design of Experiments (DOE) for Robust Nanoparticle Formulation

by Ritu Gupta, Mahua Sarkar and Huan Xie

Polymers 2026, 18(16), 2034; https://doi.org/10.3390/polym18162034 - 21 Aug 2026

Viewed by 532

Abstract

Design of experiments (DOE) offers a powerful, systematic framework for optimizing nanoparticle (NP) formulations by replacing inefficient one-factor-at-a-time (OFAT) methods. By enabling the simultaneous evaluation of multiple variables, DOE uncovers critical factor interactions and identifies true global optima—critical for quality-by-design approaches. Despite its [...] Read more.

Design of experiments (DOE) offers a powerful, systematic framework for optimizing nanoparticle (NP) formulations by replacing inefficient one-factor-at-a-time (OFAT) methods. By enabling the simultaneous evaluation of multiple variables, DOE uncovers critical factor interactions and identifies true global optima—critical for quality-by-design approaches. Despite its potential for systematic innovation, DOE remains underutilized in nanomedicine due to its perceived complexity; this review provides a practical roadmap to bridge the gap between statistical theory and robust NP optimization. It provides a practical overview of DOE concepts, including factor selection, design choice, graphical interpretation of results (perturbation/contour plots), model validation (regression analysis and ANOVA), and numerical optimization via desirability function (D). Common pitfalls and best-practice strategies are discussed to support reliable model building and decision-making. A practical case study on poly(lactic-co-glycolic acid) (PLGA) NPs illustrates a multistage workflow: utilizing Taguchi screening to isolate key factors, followed by central composite design (CCD), for precise surface mapping. Numerical optimization using Design-Expert^® software maximized EE% (highest importance) within size/zeta ranges, yielding optimal conditions (5 mg drug amount, 4 mL aqueous volume; D = 0.961). Confirmation runs (EE 41.2%, NP size 124 nm, zeta potential −15 mV) validated predictions (EE 47.6%, NP size 133 nm, zeta potential −17.2 mV), confirming model reliability. Ultimately, by bridging conceptual foundations with practical implementation, this review aims to encourage broader adoption of DOE, particularly among emerging formulation scientists, and serves as a roadmap to accelerate scalable NP development, fostering data-driven innovation and improving efficiency in nanomedicine research. Moreover, future integration of artificial intelligence (AI) and artificial neural networks (ANNs) with DOE will drive a predictive, data-driven approach to NP optimization—accelerating robust, scalable, and regulatory-ready nanomedicine development with fewer experiments. Full article

(This article belongs to the Special Issue Polymer Innovations for Advanced Biomedical Applications: Insights and Developments)

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22 pages, 3837 KB

Open AccessArticle

Effect of Ergothioneine on the Stability of Hyaluronic Acid-Based Wound-Healing Materials

by Tianyu Ma, Shuangshuang Qi, Junkai Liu, Dongjiao Li, Xia Li, Shiyue Hu, Fuhua Zheng, Ruiyan Wang, Yang Su, Yunjiao Chi, Xueqi Zhao, Zhen Qin and Hao Wu

Polymers 2026, 18(16), 2033; https://doi.org/10.3390/polym18162033 - 21 Aug 2026

Viewed by 361

Abstract

Hyaluronic acid (HA)-based hydrogels are widely used as wound-healing materials and topical delivery systems because of their excellent biocompatibility, water retention capacity, and ability to promote cell migration. However, HA is prone to oxidative chain scission, which reduces molecular weight and compromises formulation [...] Read more.

Hyaluronic acid (HA)-based hydrogels are widely used as wound-healing materials and topical delivery systems because of their excellent biocompatibility, water retention capacity, and ability to promote cell migration. However, HA is prone to oxidative chain scission, which reduces molecular weight and compromises formulation stability and functional performance. This study evaluated the feasibility of ergothioneine (EGT) as a candidate antioxidant stabilizing excipient in a model HA-based wound-healing material. CCK-8 assays assessed the biocompatibility of EGT in L929 mouse fibroblasts after 24 h of exposure, and a stress-screening framework including Fenton oxidation, high-temperature/high-humidity treatment, light exposure, and quiescent storage at 4 °C was established. The results showed that Fenton oxidation markedly induced HA degradation, whereas EGT incorporation effectively protected HA structural integrity under oxidative stress. Cell scratch assays further demonstrated that EGT did not interfere with the ability of HA to promote cell migration. EGT may serve as a candidate antioxidant stabilizing excipient for HA-based wound-healing materials, improving HA structural and material stability under oxidative challenge while preserving HA-associated cell-migration function. Full article

(This article belongs to the Section Polymer Applications)

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18 pages, 13089 KB

Open AccessArticle

Pre-Damage Strengthening of Heavy-Duty Steel Crane Girders Using Bonded CFRP Plates for Fatigue Life Enhancement

by Xiaoqing Zhao, Yuzhu Liang, Nan Jin and Zhiwei Liu

Polymers 2026, 18(16), 2032; https://doi.org/10.3390/polym18162032 - 21 Aug 2026

Viewed by 253

Abstract

In recent years, premature fatigue issues in heavy-duty steel crane girders have occurred frequently, underscoring an urgent need to establish targeted life extension methods. Compared with post-crack repair after macroscopic fatigue cracks have appeared, it is more practical to delay or even prevent [...] Read more.

In recent years, premature fatigue issues in heavy-duty steel crane girders have occurred frequently, underscoring an urgent need to establish targeted life extension methods. Compared with post-crack repair after macroscopic fatigue cracks have appeared, it is more practical to delay or even prevent the formation of such cracks in fatigue-sensitive zones of the crane girder. Extensive research has demonstrated that bonding Carbon Fiber-Reinforced Polymer (CFRP) plates can significantly enhance the fatigue life of defective components. However, most existing studies focus on thin plates with pre-existing macroscopic cracks, with limited attention given to scenarios involving thick plates or intervention before crack initiation. Therefore, this study focuses on the fatigue problem around bolt holes in the lower flange of heavy-duty steel crane girders. It investigates the life extension method of bonding CFRP plates prior to macroscopic crack formation. Through finite element analysis and comparative fatigue tests, the fatigue life enhancement mechanism was preliminarily interpreted. The effectiveness of this method is validated, and a practical CFRP bonding strategy is proposed to significantly improve the fatigue life of the lower flange in heavy-duty steel crane girders. Full article

(This article belongs to the Special Issue Advanced Polymeric Materials for Buildings)

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38 pages, 1762 KB

Open AccessReview

Recycling of Flexible Plastic Films: Emergent Technologies

by Jacob S. Licht, Marina Tsianou and Paschalis Alexandridis

Polymers 2026, 18(16), 2031; https://doi.org/10.3390/polym18162031 - 21 Aug 2026

Viewed by 506

Abstract

Plastic is a valuable material for packaging of food and pharmaceuticals, protective wrappings in construction and agriculture, and fluid storage. Flexible plastic or plastic film waste from packaging, agriculture, and construction applications grows at a rate of at least 92 million metric tons [...] Read more.

Plastic is a valuable material for packaging of food and pharmaceuticals, protective wrappings in construction and agriculture, and fluid storage. Flexible plastic or plastic film waste from packaging, agriculture, and construction applications grows at a rate of at least 92 million metric tons a year, is considered challenging to recycle, and is typically landfilled. In recent years, there have been great advancements in plastic recycling technology in order to deal with the global challenge of plastic waste buildup and support legislation from a local to national level to implement recycling. This work highlights the most recent advancements in plastic film recycling. Plastic films are mono- or multilayered based on what their applications will be, with multilayer multimaterial films being the more challenging feedstock for recycling. Mechanical recycling cannot easily process flexible films. Pyrolysis can use polyolefin-based film as feedstock but is not practiced at scale to match the rate of plastic film waste generation, and incineration can recover energy from film feedstock but is not recycling plastic. This has motivated the development of new recycling technologies designed around plastic films. Better characterization technologies to identify film compositions in municipal waste streams have been key to sorting out film feedstock for mechanical recycling and the baling of flexible plastic waste, but they struggle with multilayer films and black plastic. Compatibilization enables the recycling of mixed plastic waste but requires polymer compositions for selecting specific compatibilizers. Dissolution–precipitation recovers individual types of polymers from multilayer films and, at the same time, can purify polymers from additives or contaminants, but requires intense solvent processing and associated energy. Delamination of multilayer films can separate and recover solid films of polyolefins at relatively low amounts of solvent but requires quality feedstock to be efficient. Both dissolution–precipitation and delamination recycling of films recover the original polymer molecules and maintain their embodied energy, hence support circularity. In the case of PET-containing films, depolymerization to recover PET monomers offers opportunities to recycle challenging film feedstock. Full article

(This article belongs to the Special Issue Advances in Recycling and Reuse of Polymers)

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40 pages, 5340 KB

Open AccessReview

Green Synthesis and Functional Design of Polypyrrole-Based Nanomedicines for Cancer Theranostics: A Critical Review and Sustainability-Guided Perspective

by Jiaqiao Zhong and Yuanzhe Li

Polymers 2026, 18(16), 2030; https://doi.org/10.3390/polym18162030 - 21 Aug 2026

Viewed by 413

Abstract

Nanomedicine has advanced cancer theranostics via targeted delivery and phototherapy, yet many high-performance systems rely on inorganic or metal-intensive materials synthesized through energy-demanding routes, raising concerns about biocompatibility, environmental accumulation, and sustainability. This review re-evaluates polypyrrole (PPy)-based nanomedicines from a green chemistry perspective, [...] Read more.

Nanomedicine has advanced cancer theranostics via targeted delivery and phototherapy, yet many high-performance systems rely on inorganic or metal-intensive materials synthesized through energy-demanding routes, raising concerns about biocompatibility, environmental accumulation, and sustainability. This review re-evaluates polypyrrole (PPy)-based nanomedicines from a green chemistry perspective, shifting focus from performance-centric optimization to sustainability-guided design. PPy, an organic conductive polymer with near-infrared photothermal activity and structural tunability, offers a promising platform. However, pristine PPy suffers from limited functionality, poor biodegradability, and insufficient reactive oxygen species (ROS) generation. Reported FeCl₃-, CuCl₂-, and Fe²⁺/H₂O₂-mediated routes are compared to examine formulation-specific relationships among synthesis conditions, polymer characteristics, redox behavior, ROS-related function, and process burdens. Because the underlying studies differ in composition, processing, purification, and assay conditions, these comparisons are used to identify evidence-supported trade-offs and data gaps rather than to establish a universal causal hierarchy. Green strategies are critically assessed, including one-step carboxylated copolymerization for backbone degradability and metal–polyphenol networks for catalytic ROS amplification. To organize the heterogeneous evidence, this review introduces a PPy-specific dual-axis evidence map that considers process-related sustainability alongside biofunctional performance. This qualitative tool is intended to identify trade-offs and evidence gaps rather than provide a validated sustainability score. Full article

(This article belongs to the Section Polymer Applications)

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25 pages, 3879 KB

Open AccessReview

Progress in Sol–Gel-Derived Phenolic Aerogels: Control of Network Topology, Drying Technologies, and Functional Modification

by Hongwei Yang, Zongyi Deng, Minxian Shi and Zhixiong Huang

Polymers 2026, 18(16), 2029; https://doi.org/10.3390/polym18162029 - 21 Aug 2026

Viewed by 494

Abstract

Phenolic aerogels, owing to their low density, high char yield, large specific surface area, and well-defined three-dimensional topological networks, hold considerable promise for applications in extreme thermal protection and multifunctional material systems. The sol–gel process, a cornerstone methodology for constructing the three-dimensional nanoporous [...] Read more.

Phenolic aerogels, owing to their low density, high char yield, large specific surface area, and well-defined three-dimensional topological networks, hold considerable promise for applications in extreme thermal protection and multifunctional material systems. The sol–gel process, a cornerstone methodology for constructing the three-dimensional nanoporous architecture of these materials, critically governs the resulting microstructural topology and macroscopic performance through its reaction kinetics, phase-separation behavior, and drying dynamics. This review systematically surveys recent advances in the sol–gel synthesis of phenolic aerogels, focusing on the polycondensation mechanisms operative under acidic and basic catalytic conditions, nucleation-and-growth kinetics, and strategies for tailoring multiscale pore structures. It further provides a comparative analysis of interfacial regulation mechanisms for capillary-stress elimination across supercritical drying, freeze-drying, and ambient-pressure drying routes. We also dissect the structure–property relationships underpinning Knudsen-effect-mediated gaseous thermal insulation, multi-scale hybrid network toughening, and inorganic phase-transition-induced in situ ceramization for thermal protection, demonstrating the synergistic optimization of thermal insulation, structural load-bearing, and ablation resistance. Finally, we summarise current applications in extreme thermal protection, environmental adsorption, electromagnetic interference shielding, and electrochemical energy storage and highlight future directions towards green, scalable manufacturing and intelligent materials design. Full article

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

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24 pages, 1879 KB

Open AccessReview

Toward In Situ Stabilization of Raw Chinese Lacquer (Toxicodendron vernicifluum): Current Evidence, Processing Strategies, and Research Challenges

by Ziyue Zhang, Baoju Jin, Xiaotong Li, Hanyun Gao and Xinhao Feng

Polymers 2026, 18(16), 2028; https://doi.org/10.3390/polym18162028 - 21 Aug 2026

Viewed by 302

Abstract

Raw Chinese lacquer, tapped from the sap of Toxicodendron vernicifluum, is a natural water-in-oil microemulsion containing urushiol, polysaccharides, proteins, and laccase. Because this reactive system continues to oxidize and polymerize after harvesting, handling conditions directly determine water content, viscosity, and later film-forming [...] Read more.

Raw Chinese lacquer, tapped from the sap of Toxicodendron vernicifluum, is a natural water-in-oil microemulsion containing urushiol, polysaccharides, proteins, and laccase. Because this reactive system continues to oxidize and polymerize after harvesting, handling conditions directly determine water content, viscosity, and later film-forming performance. This review analyzes potential in situ stabilization routes that couple purification, low-temperature vacuum dehydration, and quality conditioning at, or near, the collection site. Emphasis is placed on how laccase retention, oxygen exposure, and urushiol polymerization are controlled together to limit transport losses and premature crusting. Portable filtration devices, reported centrifugal filtration systems, and proposed vacuum dehydration strategies are compared in terms of throughput, field compatibility, and process control. Physical and bio-based conditioning strategies, including shear adjustment, oxygen management, and natural film-forming aids, are further considered for on-site regulation. Surface-enhanced Raman spectroscopy (SERS) and portable spectroscopic devices are examined as feedback tools for parameter adjustment under field temperatures, humidity, and storage variation; however, these signals are treated as decision-support indicators that still require lacquer-specific calibration after tapping. The central task is to define a field-compatible process window for water removal, laccase retention, viscosity control, drying behavior, and storage stability before downstream coating preparation. The remaining challenges involve miniaturized equipment, standardized evaluation, evidence-level classification, and dynamic control of coupled variables. Full article

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

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31 pages, 2545 KB

Open AccessArticle

Integrated Multi-Criteria Decision-Making for the Selection of Natural and Synthetic Fiber-Reinforced Composites for Unmanned Aerial Vehicle Micro-Turbojet Engine Inlets

by Abderraouf Gherissi

Polymers 2026, 18(16), 2027; https://doi.org/10.3390/polym18162027 - 21 Aug 2026

Viewed by 307

Abstract

This study develops an integrated Analytic Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) multi-criteria decision-making (MCDM) framework to systematically evaluate and rank composite material combinations based on 24 fibers (16 natural and 8 synthetic), 15 matrices [...] Read more.

This study develops an integrated Analytic Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) multi-criteria decision-making (MCDM) framework to systematically evaluate and rank composite material combinations based on 24 fibers (16 natural and 8 synthetic), 15 matrices (thermosets, thermoplastics, and biopolymers), and 9 fiber volume fractions (30–70%) for UAV inlet applications. Ten evaluation criteria covering technical performance, environmental sustainability, and economic viability were weighted using AHP pairwise comparisons based on Saaty’s 1–9 scale, yielding a consistency ratio of CR = 0.009, which confirms the reliability of the judgments. The TOPSIS analysis identified Carbon (PAN-HM)/Epoxy as the optimal composite material, achieving the highest TOPSIS score of 0.8893. In contrast, Flax/Epoxy emerged as the best natural fiber composite, with a TOPSIS score of 0.2686, indicating a performance gap of approximately 231% in favor of the synthetic composite. Comprehensive sensitivity analysis across four weighting scenarios (Equal, Technical, Environmental, and Economic) confirmed the stability of the reinforcement rankings, with Carbon (PAN-HM) remaining the top synthetic fiber and flax the top natural fiber across all scenarios. The findings contribute to the growing body of knowledge on sustainable aerospace materials and provide practical guidance for UAV designers seeking to optimize material selection for micro-turbojet engine inlet components, supporting the development of more environmentally responsible UAV designs while maintaining the performance requirements for safe and reliable operation. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites: Processing, Simulation, Properties and Applications)

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26 pages, 4613 KB

Open AccessArticle

Simulation-Oriented Rule-Driven Geometric Modeling of Polymer-Fiber Weft-Knitted Structures for Moisture-Transfer Prediction

by Miao Miao, Nana Li, Hao Zhang, Yuxiao Tang, Tianqi Yang and Xiaodong Zhang

Polymers 2026, 18(16), 2026; https://doi.org/10.3390/polym18162026 - 21 Aug 2026

Viewed by 321

Abstract

Polymer-fiber weft-knitted textiles are widely used in functional apparel and moisture-management materials, but their complex loop topology, yarn-level porosity, and interlayer hierarchy make simulation-oriented geometric modeling challenging. Conventional control-point and interpolated-curve methods often have limitations in representing knitting actions, maintaining yarn-path continuity, and [...] Read more.

Polymer-fiber weft-knitted textiles are widely used in functional apparel and moisture-management materials, but their complex loop topology, yarn-level porosity, and interlayer hierarchy make simulation-oriented geometric modeling challenging. Conventional control-point and interpolated-curve methods often have limitations in representing knitting actions, maintaining yarn-path continuity, and generating meshable geometries. This study proposes a rule-driven geometric modeling method for polymer-fiber weft-knitted structures using the yarn centerline as the basic geometric carrier. Knitting actions, including knit, tuck, float, plating, and double-needle-bed assignment, are converted into reusable local path-generation rules and integrated through pattern-matrix input, action recognition, parametric centerline generation, continuous stitching, and standardized output. The method represents single-bed and double-bed structures within a unified framework, including plain, jacquard, plated, tuck, rib, interlock, half-cardigan, full-cardigan, and purl structures. Compared with an interpolated-curve method, the curvature-jump rate of four representative structures decreases from 40.78–69.23% to 0–0.31%, with markedly reduced maximum bending angles. Mesh-generation results show continuous meshes with improved element quality for complex double-bed structures. A moisture-transfer simulation of a fully plated plain-knitted structure gives one-way transport indices of −122.3187 and 122.2472 for face- and back-side liquid entry, with relative errors of 1.74% and 0.50% compared with experiments. These results indicate that the proposed method provides reproducible and meshable geometric input for structure–property modeling and moisture-transfer prediction of polymer-fiber knitted textiles. Full article

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

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33 pages, 6768 KB

Open AccessArticle

Mechanistic Insights into Drying and Film Evolution of PVA–Bentonite Coatings: The Role of Solids Content and Coating Composition Optimization

by Sarojini Verma, George D. Verros and Raj Kumar Arya

Polymers 2026, 18(16), 2025; https://doi.org/10.3390/polym18162025 - 21 Aug 2026

Viewed by 891

Abstract

Poly(vinyl alcohol) (PVA)–bentonite composite coatings combine a hydrophilic polymer with a naturally abundant clay mineral, offering potential advantages for modifying the physicochemical and film-forming characteristics of polymer–clay coatings. However, the combined influence of PVA–bentonite composition and total solids content on drying behavior and [...] Read more.

Poly(vinyl alcohol) (PVA)–bentonite composite coatings combine a hydrophilic polymer with a naturally abundant clay mineral, offering potential advantages for modifying the physicochemical and film-forming characteristics of polymer–clay coatings. However, the combined influence of PVA–bentonite composition and total solids content on drying behavior and film evolution remains insufficiently explored. This study investigates the particle size, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), surface morphology, rheology, thixotropy, zeta potential, drying behavior, solvent transport, and film evolution of PVA–bentonite coatings prepared at total solids contents of 5 and 10 wt.% with different PVA to bentonite ratios. The drying profiles exhibited an initial relatively rapid solvent-removal stage followed by a slower stage associated with progressively restricted solvent transport during film consolidation. A lower total solids content (5 wt.%) generally accelerated drying but was associated with greater microcracking, whereas a higher total solids content (10 wt.%) produced more consolidated and comparatively uniform films with reduced solvent mobility. The combined physicochemical, rheological, drying, and morphological results demonstrate that both PVA–bentonite composition and total solids content substantially influence the structural organization and drying behavior of the coatings. Pure PVA formed a relatively uniform film but exhibited prolonged drying, while pure bentonite required the longest drying time (1083 min). Among the investigated formulations, the 50:50 PVA–bentonite coating demonstrated the shortest drying time, reaching equilibrium in approximately 480 min, while also exhibiting comparatively good film uniformity. During drying, its thickness decreased from approximately 1745 to 440 µm, corresponding to a reduction of about 1305 µm. Overall, under the investigated laboratory conditions, the 50:50 PVA–bentonite formulation provided the most favorable balance of drying behavior, film formation, and rheological characteristics among the compositions studied. These findings provide composition–structure–drying relationships that can guide further development of PVA–bentonite coating systems. At the same time, additional evaluation of mechanical, adhesion, barrier, durability, and economic performance is required to establish broader practical applicability. Full article

(This article belongs to the Section Polymer Membranes and Films)

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16 pages, 5421 KB

Open AccessArticle

Response Surface Methodology (RSM) Optimization of Electromagnetic Interference (EMI) Shielding Effectiveness in Polymer Nanocomposites with Irradiated Hybrid Carbon Nanostructures

by Anita Grozdanov, Stefan Kuvendziev, Iva Dimitrievska, Mirko Marinkovski, Martin Stojchevski, Andrea Petanova, Perica Paunović, Duska Kleut and Svetlana Jovanović

Polymers 2026, 18(16), 2024; https://doi.org/10.3390/polym18162024 - 21 Aug 2026

Viewed by 324

Abstract

In recent decades, due to the rapid development and application of wireless communication, flexible electronics, and smart devices, electromagnetic interference (EMI) and radiation pollution have been intensified, creating an urgent demand for efficient EMI shielding materials. Carbon nanostructures such as graphene and carbon [...] Read more.

In recent decades, due to the rapid development and application of wireless communication, flexible electronics, and smart devices, electromagnetic interference (EMI) and radiation pollution have been intensified, creating an urgent demand for efficient EMI shielding materials. Carbon nanostructures such as graphene and carbon nanotubes are considered promising candidates due to their excellent properties, such as high electrical conductivity, low density, large specific surface area, and flexibility. This work reports our recent results in the design and testing of polymer nanocomposites with irradiated hybrid carbon nanostructure (graphene/multi-walled carbon nanotubes) used as EMI shielding materials. Five representative composites with varying filler loadings (AH of 15% and AM1 of 20 wt%), thicknesses (0.208–0.48 mm), and e-beam irradiation doses (from 50 to 400 kGy) were systematically characterized using SEM, FTIR, TGA/DSC, and vector network analyzer (VNA) measurements in the S-band (2.65–3.90 GHz). The effects of different e-beam irradiation doses and hybrid carbon contents on conductive network construction, interface engineering, and porous or layered structures on EMI shielding performance are discussed. Experimental results show that all studied composites exhibited strong absorption-dominant behavior (SE_A), while the multiple reflection component (SE_M) was found to be negligible. Both filler loading and sample thickness significantly enhanced shielding performance, with a pronounced synergistic interaction observed between these parameters. A quadratic Response Surface Methodology (RSM) model was developed to correlate the total shielding effectiveness (SE_T) with thickness and filler content, yielding high predictive accuracy (R² > 0.96). The model enables efficient optimization of composite design for targeted shielding levels. Full article

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39 pages, 27685 KB

Open AccessArticle

Fiber-Reinforced One-Part Geopolymer Mortars Incorporating Red Mud, Ceramic Powder, and MgO: Performance Under Different Curing Regimes and Curing-Based Environmental Assessment

by Mohammed Dakhel Al Bdairi, Orhan Canpolat, Mucteba Uysal, Ömer Can Özen, Ömer Faruk Kuranlı and Aygül Zara Kebir

Polymers 2026, 18(16), 2023; https://doi.org/10.3390/polym18162023 - 20 Aug 2026

Viewed by 331

Abstract

One-part geopolymer mortars provide an alternative to cementitious materials by using dry activators and industrial by-products. This study evaluated a multi-precursor matrix containing slag, fly ash, ceramic powder, red mud, and 5% MgO, reinforced with polyvinyl alcohol (PVA), basalt, or micro-steel fibers at [...] Read more.

One-part geopolymer mortars provide an alternative to cementitious materials by using dry activators and industrial by-products. This study evaluated a multi-precursor matrix containing slag, fly ash, ceramic powder, red mud, and 5% MgO, reinforced with polyvinyl alcohol (PVA), basalt, or micro-steel fibers at 0.4% and 0.8% by volume. Specimens were cured at 20 ± 2 °C or at 80 °C for 24 h and assessed for flowability, mechanical properties, ultrasonic pulse velocity (UPV), Böhme abrasion, 24 h water absorption, and sorptivity. XRD, FTIR, and SEM/EDS were used only to compare by heat-cured mixtures. The results showed that at 28-day, heat curing increased compressive strength by 39.5–71.8%, flexural strength by 29.2–134.4%, and UPV by 20.5–36.4%, while reducing sorptivity by 12.2–35.7% relative to ambient curing. PVA reduced flowability likely because of its hydrophilic surface and high surface area. For 0.8PVA, the flow diameter was 23.6% below the reference, whereas the 28-day heat-cured flexural strength reached 7.5 MPa, with the lowest abrasion thickness loss of 0.63 mm. Micro-steel mixtures maintained compressive strength comparable to the reference, reaching 72–73 MPa at 28-day. Heat curing reduced water absorption in PVA and basalt mixtures, whereas the reference and micro-steel mixtures showed insignificant change. Microstructural analyses suggested the formation of a more compact and reacted aluminosilicate matrix under heat-cured conditions. A screening life-cycle assessment, limited to the non-fiber-reinforced reference matrix, showed that heat-curing increased global warming potential by 7.6%, while the two solid activators contributed approximately 45% of the ambient-cured reference GWP. The findings indicate that heat curing significantly enhances the performance of one-part geopolymers, while fiber selection provides additional mechanical and durability improvements. Full article

(This article belongs to the Special Issue Advances in Fiber-Reinforced Polymers for Construction: Properties and Application)

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23 pages, 7340 KB

Open AccessArticle

VOC Emission Reduction and Rheological Optimization of Recycled Asphalt with USP Warm Mix Additive

by Zhaoyang Wang, Bowen Guan, Xuetao Wang, Anhua Xu, Xin Zheng and Yue Zhang

Polymers 2026, 18(16), 2022; https://doi.org/10.3390/polym18162022 - 20 Aug 2026

Viewed by 214

Abstract

To mitigate high-temperature VOC emissions and reduce construction temperatures in recycled asphalt, a USP warm mix additive was introduced into waste soybean oil (WSO) recycled asphalt. This study systematically investigates the effects of USP content (1%, 3%, 5%, and 7%) and construction temperature [...] Read more.

To mitigate high-temperature VOC emissions and reduce construction temperatures in recycled asphalt, a USP warm mix additive was introduced into waste soybean oil (WSO) recycled asphalt. This study systematically investigates the effects of USP content (1%, 3%, 5%, and 7%) and construction temperature (140 °C and 160 °C) on VOCs emission characteristics, inhibition mechanisms, and rheological performance. The results show that USP reduces total VOC emissions, with the key inhibition effect achieved at 5% USP. At 160 °C, the VOCs inhibition rate reached 39.5% at 5% USP, while at 140 °C it increased to 80.8%; the findings suggest that lower temperatures enhance the inhibitory effect. The results show USP cuts emissions via physical mechanisms. However, the significant FTIR and DSC analyses suggest that VOC reduction appears to be primarily governed by physical mechanisms, including phase-change cooling, physical encapsulation, and migration retardation, without altering the chemical structure of asphalt. Moreover, the important rheological results indicate that although USP slightly decreases the high-temperature complex modulus and rutting factor, the evidence demonstrates that it improves the percent recovery (R_0.1 from 53% to 66%; R_3.2 from 21% to 40%) and low-temperature crack resistance through decreased stiffness S and increased m-value. In light of these significant findings, the study demonstrates that USP exhibits a multi-performance balance, appearing to reduce VOC emissions and improve workability while moderately weakening high-temperature deformation resistance. Notwithstanding the reduced high-temperature resistance, the key evidence could demonstrate that USP enhances elastic recovery and low-temperature performance in the results. The optimal USP content appears to be 5%, providing the critical compromise between emission reduction and pavement performance for WSO recycled asphalt. Full article

(This article belongs to the Special Issue Eco-Innovative Polymer Materials for Sustainable Infrastructure Applications)

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18 pages, 28737 KB

Open AccessArticle

Optimization of Bioink Formulations and Bioprinting Conditions for Enhanced Cell Viability in Particle-Containing Constructs

by Fiona Ye Rojo Acero, Daniel F. de Castro Hernández, María Lisseth Flores-Cedillo, Juan José Uriarte, Ainhoa Herrero, Raquel Villa and Luis M. Rodríguez-Lorenzo

Polymers 2026, 18(16), 2021; https://doi.org/10.3390/polym18162021 - 20 Aug 2026

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Abstract

Extrusion-based bioprinting imposes stringent mechanical constraints on bioink formulations, yet the rheological parameters governing cell survival during the printing process are rarely reported in a standardized way, limiting cross-study comparison. In this work, we systematically characterized the viscoelastic properties of alginate/methylcellulose bioinks incorporating [...] Read more.

Extrusion-based bioprinting imposes stringent mechanical constraints on bioink formulations, yet the rheological parameters governing cell survival during the printing process are rarely reported in a standardized way, limiting cross-study comparison. In this work, we systematically characterized the viscoelastic properties of alginate/methylcellulose bioinks incorporating strontium-enriched hydroxyapatite (Sr-OHAp) particles and Poloxamer 188, and assessed their effect on PANC-1 cell viability in bioprinted constructs. The power law consistency index K and pseudoplasticity index n were used as quantitative descriptors of bioink behavior. Addition of Poloxamer 188 reduced K by 52.1% in particle-free inks and by 64.6% in particle-containing inks, while n remained largely unchanged (≤2% variation), indicating that particles selectively modulate consistency without compromising shear-thinning behavior. On day 1, bioprinted constructs showed lower cell viability than cell-seeded scaffolds (53.9–58.9% vs. 96.7%); however, constructs containing Sr-OHAp (B3) displayed progressive recovery, reaching 84.0% viability by day 7, compared to 72.9% for particle-free bioinks (B1). These results demonstrate that Sr-OHAp particles act as rheological sensitizers that reduce extrusion-induced shear stress while simultaneously promoting long-term cell recovery, likely through their bioactive surface chemistry. We propose that systematic reporting of K and n indices should become standard practice in bioprinting studies to enable rational bioink design and consistent knowledge accumulation across the field. Full article

(This article belongs to the Special Issue Advanced Polymer Additive Manufacturing for Functional, Sustainable, and High-Performance Applications)

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20 pages, 7733 KB

Open AccessArticle

Effect of Waste MDF-Derived Carbonisate Morphology on the Dielectric Stability of Epoxy-Based Composites

by Agata Wieczorska

Polymers 2026, 18(16), 2020; https://doi.org/10.3390/polym18162020 - 20 Aug 2026

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Abstract

This paper presents the next stage of research on epoxy-glass composites modified with carbonisate obtained from the pyrolysis of waste MDF boards. Previous studies focused on assessing the mechanical properties of the developed material, while the aim of this work was to expand [...] Read more.

This paper presents the next stage of research on epoxy-glass composites modified with carbonisate obtained from the pyrolysis of waste MDF boards. Previous studies focused on assessing the mechanical properties of the developed material, while the aim of this work was to expand its characterization to include assessment of electrical properties and to determine the potential use of carbonisate as a functional filler in electrically insulating composites. The effect of carbonisate particle size (<500, <1000, and <1500 µm), carbonisate content (5% and 7.5% by weight), and resin-to-reinforcement ratio on the surface and volume resistivity of epoxy-glass composites was analysed. The microstructure of the materials was assessed using optical microscopy and scanning electron microscopy (SEM). To quantitatively assess changes in electrical insulating properties, we used logarithmic resistivity analysis and our own dielectric destabilization index (D), which serves as a comparative engineering index. The obtained results showed that increasing the carbonisate particle size leads to a gradual decrease in the electrical insulating properties of the composites and an increase in their structural heterogeneity. The highest dielectric destabilization index value was obtained for the composite containing 7.5% carbonisate with a fraction <1500 µm (D = 0.403). Microstructural observations confirmed the presence of agglomerates, micropores, and local structural discontinuities, which can reduce the electrical resistivity of the tested materials. The conducted studies confirmed the possibility of using carbonisate obtained from waste MDF (Medium-Density Fibreboard) boards as a functional filler in epoxy-glass composites. The obtained results constitute the next stage of comprehensive characterization of the developed material and indicate that the appropriate selection of the carbonisate morphology and the composition of the composite may enable shaping its electrical insulating properties depending on the planned application. Full article

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

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2 pages, 780 KB

Open AccessCorrection

Correction: Shirosaki et al. The Impact of the Molecular Weight of Degradation Products with Silicon from Porous Chitosan–Siloxane Hybrids on Neuronal Cell Behavior. Polymers 2023, 15, 3272

by Yuki Shirosaki, Federica Fregnan, Luisa Muratori, Saki Yasutomi, Stefano Geuna and Stefania Raimondo

Polymers 2026, 18(16), 2019; https://doi.org/10.3390/polym18162019 - 20 Aug 2026

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Abstract

In the original publication [...] Full article

(This article belongs to the Section Polymer Chemistry)

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29 pages, 5027 KB

Open AccessArticle

Multiparametric Optimization of Fabrication of Electrospun PVA Nanofibers for Utilization as Wound Dressing Mats

by Tshepang Mqatywa, Mehrab Mahdian, Paula Ossowicz-Rupniewska, Karolina Zyburtowicz-Ćwiartka, Karolina Bilska, Anna Nowak, Tímea Beskid, Mária Laki, András József Laki, János Juhász, Tamás Pardy and Franciska Erdő

Polymers 2026, 18(16), 2018; https://doi.org/10.3390/polym18162018 - 20 Aug 2026

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Abstract

Electrospun poly (vinyl alcohol) (PVA) nanofibers are promising materials for wound dressings because of their high porosity, large surface area, and structural similarity to the extracellular matrix. In this study, a Box–Behnken design was used to optimize the effects of applied voltage, flow [...] Read more.

Electrospun poly (vinyl alcohol) (PVA) nanofibers are promising materials for wound dressings because of their high porosity, large surface area, and structural similarity to the extracellular matrix. In this study, a Box–Behnken design was used to optimize the effects of applied voltage, flow rate, spinning distance, and needle gauge on the fabrication of electrospun PVA nanofiber mats using an 8% (w/v) PVA precursor solution. Fiber morphology, diameter, porosity, thickness, swelling capacity, and thermal properties were evaluated. Stable electrospinning conditions produced uniform, bead-free nanofibers with mean diameters ranging from 198.9 ± 3.6 to 228.7 ± 1.5 nm. Needle gauge and flow rate were identified as the most influential parameters affecting fiber diameter, while voltage and spinning distance showed interaction-dependent effects. Thinner fibers generated using finer needles resulted in higher porosity and enhanced swelling behavior, whereas larger needle diameters produced thicker and denser mats. Thermal analysis demonstrated good thermal stability, with degradation onset temperatures ranging from approximately 225 to 280 °C, and melting transitions consistently occurring at 190–193 °C. The results establish clear process–structure–property relationships and demonstrate that multiparametric optimization enables reproducible fabrication of PVA nanofibers with tunable characteristics relevant for wound-dressing applications. Full article

(This article belongs to the Section Polymer Applications)

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23 pages, 5436 KB

Open AccessArticle

Effects of Syringaldehyde/Gum Arabic Composite Chitosan Thermochromic Microcapsules on the Coating Properties of Basswood Surface

by Wenjing Chang, Jingyi Hang and Xiaoxing Yan

Polymers 2026, 18(16), 2017; https://doi.org/10.3390/polym18162017 - 20 Aug 2026

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Abstract

Thermochromic wood coatings hold promising application prospects, yet conventional thermochromic microcapsules are limited by monotonous color transitions and non-environmentally friendly wall materials. In this study, two formaldehyde-free thermochromic microcapsules were prepared via spray drying using crystal violet lactone (CVL) and bisphenol A (BPA) [...] Read more.

Thermochromic wood coatings hold promising application prospects, yet conventional thermochromic microcapsules are limited by monotonous color transitions and non-environmentally friendly wall materials. In this study, two formaldehyde-free thermochromic microcapsules were prepared via spray drying using crystal violet lactone (CVL) and bisphenol A (BPA) as the core system, with chitosan–syringaldehyde (SA-MCs, decyl alcohol as solvent, Schiff base crosslinking) and chitosan–gum Arabic (GA-MCs, lauryl alcohol as solvent, electrostatic complex coacervation) as the wall materials, respectively. These microcapsules were incorporated into basswood ultraviolet (UV) coatings at mass fractions of 1%, 3%, 5%, 7%, and 9%. With increasing microcapsule content, the gloss of both coatings decreased progressively, roughness increased gradually, and the color-changing amplitude, expressed as the color difference (ΔE), was continuously enhanced. At 9% addition, the SA-MC coating exhibited a moderate transition from light yellow to yellow-green (ΔE = 7.2), while the GA-MC coating displayed a dramatic reversible change from deep blue to light gray (ΔE = 42.4), both with good reversibility. In terms of mechanical properties, SA-MCs exhibited higher hardness, both systems achieved an impact resistance grade of 3, and GA-MCs demonstrated superior adhesion. After 24 h of short-term UV accelerated aging, GA-MCs still maintained a higher thermochromic response, albeit with more severe gloss loss. In summary, GA-MCs are superior in color-changing amplitude and adhesion, while SA-MCs offer advantages in gloss retention and hardness, providing a reference for material selection in the application of smart wood finishing. Full article

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

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28 pages, 17530 KB

Open AccessArticle

Compositionally Tunable Interpolymer System for Charge-Selective Recovery of Gold Cyanide from Ferrocyanide-Rich Solutions

by Meruyert Suleimenova, Talkybek Jumadilov, Juozas Gražulevičius, Khuangul Khimersen and Meruyert Mukanova

Polymers 2026, 18(16), 2016; https://doi.org/10.3390/polym18162016 - 20 Aug 2026

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Abstract

Selective recovery of gold from cyanide leach liquors is hindered by the co-dissolution of iron minerals that generate ferrocyanide complexes which strongly compete with [Au(CN)₂]⁻ at ion-exchange sorbents. Here, we investigate mixed-bed interpolymer systems (IPS) composed of a strong-acid sulfonated [...] Read more.

Selective recovery of gold from cyanide leach liquors is hindered by the co-dissolution of iron minerals that generate ferrocyanide complexes which strongly compete with [Au(CN)₂]⁻ at ion-exchange sorbents. Here, we investigate mixed-bed interpolymer systems (IPS) composed of a strong-acid sulfonated polystyrene–divinylbenzene cation exchanger (TC007, Na⁺ form) and a strong-base quaternary ammonium anion exchanger (AV-17-8, Cl⁻ form) as a charge-selective platform for gold cyanide recovery. IPS compositions spanning cation-to-anion molar ratios from 6:0 to 0:6 were evaluated in batch contact with binary model solutions containing 30 mg L⁻¹ each of [Au(CN)₂]⁻ and [Fe(CN)₆]⁴⁻ at pH 10 and 25 °C. The optimal 1:5 IPS achieved an [Au(CN)₂]⁻ extraction degree of 79.88% and a selectivity coefficient β = D_Au/D_Fe = 4.95 at 48 h, whereas the pure AV-17-8 anion exchanger (0:6) reached only 37.55% Au extraction at 48 h, following an atypical delayed-uptake kinetic profile rather than the rapid, near-quantitative capture expected of an unmodified strong-base resin. Sorption kinetics were best described by a pseudo-second-order model (R² = 0.9992), confirming ion exchange at quaternary ammonium sites as the dominant rate-controlling step, with a ~30-fold increase in k₂ for [Au(CN)₂]⁻ in the 1:5 IPS relative to AV-17-8 alone. FTIR spectroscopy and TGA-DSC revealed the incorporation of metal cyanide complexes into the IPS matrix, with diagnostic C≡N stretching bands at 2108.7 and 2034.1 cm⁻¹ and an additional thermal event at 200–280 °C. These findings establish compositionally tunable IPS based on commercially available resins as a charge-selective sorbent platform demonstrating a capacity to regenerate under single-cycle elution conditions for gold cyanide recovery from ferrocyanide-containing process streams while highlighting the need for further evaluation under industrial Fe:Au ratios. Full article

(This article belongs to the Section Circular and Green Sustainable Polymer Science)

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17 pages, 22493 KB

Open AccessArticle

Synergistic Effects of Plasticizer Types on the Mechanical, Thermal, and Morphological Properties of PVC Compounds for Cable Application

by Furkan Kaya, Aysun Ekinci-Tekin, Mustafa Oksuz and Murat Ates

Polymers 2026, 18(16), 2015; https://doi.org/10.3390/polym18162015 - 19 Aug 2026

Viewed by 473

Abstract

Poly (vinyl chloride) (PVC) is widely used in many products due to its increased flexibility and processability. It is preferred in many industrial applications, especially in the plasticized PVC cable industry due to its excellent insulation properties. PVC is quite hard and can [...] Read more.

Poly (vinyl chloride) (PVC) is widely used in many products due to its increased flexibility and processability. It is preferred in many industrial applications, especially in the plasticized PVC cable industry due to its excellent insulation properties. PVC is quite hard and can be difficult to process. Therefore, it requires additives such as plasticizers. Plasticizers typically reduce the glass transition temperature (Tg) and provide flexibility by reducing the workable temperature level. In the PVC compound production industry, phthalate-based plasticizers are preferred due to their low cost. Commonly used plasticizers are adipates, azelates, trimethylates, phthalates, benzoates, and chlorinated paraffins. The aim of the study was to investigate the plasticizer changes in PVC compounds used in cable insulation applications by synergistic effects of adipate, trimellitate, and phthalate-based plasticizers such as dioctyl terephthalate (DOTP), 2-ethyl hexyl adipate (DOA), and tris(2-ethylhexyl) benzene-1,2,4-tricarboxylate (TOTM). In this study, the effects of plasticizer additives were investigated on the structural, morphological, thermal, and mechanical properties of PVC compounds in the cable industry. Fabricated test products were characterized using characterization methods such as Fourier transform infrared-attenuated total reflectance (FTIR-ATR), scanning electron microscope–energy-dispersive X-ray (SEM-EDX) spectroscopy, thermal gravimetric analysis (TGA), tensile test, and density test. Successfully fabricated samples were tested before and after aging. The highest elongation at break of PVC flat sheet (244.96%) was obtained with the use of DOA plasticizer. The highest tensile strength was measured as 17.85 MPa for the sample containing 50 phr DOTP. Furthermore, no significant mass loss was observed up to 238 °C, while substantial decomposition occurred in the samples containing 50 phr DOTP, 50 phr DOA, and 50 phr TOTM between 238–338 °C, followed by gradual degradation at 483 °C and 683 °C. As a result, it has been determined that the use of DOA plasticizer in PVC compounds used in the cable industry is more effective than DOTP and TOTM plasticizers. Full article

(This article belongs to the Special Issue Polymer Manufacturing Processes)

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59 pages, 12745 KB

Open AccessArticle

The Effect of Natural Pozzolanic Coated Waste Tire Aggregates on the Mechanical, Transport and Durability Properties of Fiber-Reinforced and One-Part Hybrid Geopolymer Composites

by Wiam Abdelmagid Taher Elabade, Oğuzhan Yavuz Bayraktar, Halil Oğuzhan Kara, İhsan Kasım Karataş, Mehmet Uğur Yılmazoğlu, Adem Ahıskalı, Mohamed A. Salem Elmekahal and Gökhan Kaplan

Polymers 2026, 18(16), 2014; https://doi.org/10.3390/polym18162014 - 19 Aug 2026

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Abstract

This study examined the effects of coating waste tire aggregates (WTAs) with pumice, perlite, or diatomite, combined with polypropylene (PP) fiber addition, on the fresh, mechanical, transport, and durability properties of one-part hybrid geopolymer composites. Sixteen mixtures were produced using a Taguchi L16 [...] Read more.

This study examined the effects of coating waste tire aggregates (WTAs) with pumice, perlite, or diatomite, combined with polypropylene (PP) fiber addition, on the fresh, mechanical, transport, and durability properties of one-part hybrid geopolymer composites. Sixteen mixtures were produced using a Taguchi L16 design with a binder system of fly ash, CEM II/B-S cement, and sodium metasilicate powder. Coating type, WTA ratio, and PP fiber content were the key performance factors. Pumice coating performed best overall by improving the interfacial transition zone: 28-day compressive strength reached 15.5 MPa and flexural strength 1.60 MPa, while porosity and capillary water absorption decreased significantly. Among the studied WTA levels, 10% WTA yielded the most positive direct responses in compressive strength, flexural strength, toughness, and capillary water absorption, whereas higher contents weakened matrix continuity. The effect of PP fiber was response-dependent: 0.5% fiber maximized compressive strength and durability-related responses, while 2% fiber gave the greatest flexural strength and toughness; no single dosage was universally optimal. The pumice-coated series was also the most stable under high temperature, freeze–thaw, MgSO₄, and H₂SO₄ exposure. Overall, waste tire aggregates can be technically incorporated into one-part hybrid geopolymer composites; a dedicated life-cycle assessment is nevertheless required to quantify the net environmental benefit. Full article

(This article belongs to the Special Issue Research Progress on Mechanical Behavior of Polymers, 2nd Edition)

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38 pages, 29303 KB

Open AccessReview

PEEK in Harsh Oil and Gas Environments: Applications and Chemical Aging Response

by Wael Badeghaish, Ahmed Wagih and G. Lubineau

Polymers 2026, 18(16), 2013; https://doi.org/10.3390/polym18162013 - 19 Aug 2026

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Abstract

The oil and gas (O&G) industry is increasingly adopting non-metallic materials for pipelines and downhole components to mitigate corrosion, reduce maintenance costs, and improve performance in harsh service environments. Among high-performance polymers, polyether-ether-ketone (PEEK) has attracted significant attention owing to its excellent mechanical [...] Read more.

The oil and gas (O&G) industry is increasingly adopting non-metallic materials for pipelines and downhole components to mitigate corrosion, reduce maintenance costs, and improve performance in harsh service environments. Among high-performance polymers, polyether-ether-ketone (PEEK) has attracted significant attention owing to its excellent mechanical properties, thermal stability, and chemical resistance, making it a promising candidate for aggressive downhole applications. However, exposure to acids, hydrocarbons, water, CO₂, and supercritical CO₂ under high-pressure/high-temperature conditions can alter its microstructure and mechanical performance, necessitating a comprehensive understanding of its long-term behavior. This review summarizes the microstructure, properties, and current applications of PEEK in the O&G industry, including its emerging use in additive manufacturing. It further examines the fundamental mechanisms of gas and liquid diffusion, aging processes (physical, chemical, and thermal), and their effects on the morphology, thermal behavior, and mechanical properties of PEEK. By consolidating findings from studies conducted under representative O&G environments, this review identifies current knowledge gaps and future research priorities, providing guidance for the selection, qualification, and design of PEEK components for demanding oil and gas applications. Full article

(This article belongs to the Section Polymer Applications)

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16 pages, 6100 KB

Open AccessArticle

Photo-Initiated Main-Chain Scission of Poly(methyl methacrylate) in Solution at Room Temperature

by Xiao Wang, Xiangze Meng, Zhiping Xu and Rui Yang

Polymers 2026, 18(16), 2012; https://doi.org/10.3390/polym18162012 - 18 Aug 2026

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Abstract

Poly(methyl methacrylate) (PMMA), as a widely used transparent polymer material, is highly stable because of its all-carbon backbone, which makes its chain cleavage under mild conditions challenging. In this work, we report a photo-initiated solution reaction that induces main-chain scission of PMMA at [...] Read more.

Poly(methyl methacrylate) (PMMA), as a widely used transparent polymer material, is highly stable because of its all-carbon backbone, which makes its chain cleavage under mild conditions challenging. In this work, we report a photo-initiated solution reaction that induces main-chain scission of PMMA at room temperature, leading mainly to molecular-weight reduction and oligomer formation. This method requires no catalysts and does not need pre-introduction of specific groups. The degradation mechanism proposed according to DFT calculations involves the photolysis of trichloromethane to produce phosgene, which then reacts with ester groups on the side chains of PMMA to form acyl chloride groups. These acyl chloride groups further cleave under light or heat, generating radicals that trigger β-scission of the PMMA main chain through a side-chain-initiated pathway. The degradation mechanism was demonstrated experimentally, and the extent of chain scission can be regulated by temperature, O₂ and an alcohol stabilizer. Full article

(This article belongs to the Special Issue Aging, Degradation, and Lifetime Engineering of Advanced Polymeric Materials)

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26 pages, 1346 KB

Open AccessSystematic Review

Systematic Mapping of the Literature on Dextran Hydrogels Produced by Leuconostoc sp. for Agrobiotechnological Purposes

by M. De La Cruz-Noriega, Segundo Rojas-Flores, Moisés Gallozzo Cardenas, Luis Cabanillas-Chirinos, Waldo Salvatierra Espinola, Elena Hernández-del Amo and Olga Sánchez

Polymers 2026, 18(16), 2011; https://doi.org/10.3390/polym18162011 - 18 Aug 2026

Viewed by 355

Abstract

Agriculture faces the challenge of transitioning toward sustainable practices, driving the use of plant growth-promoting bacteria (PGPB). However, these bacteria suffer critical losses in viability due to environmental stress and drying processes. Although synthetic hydrogels offer protection, their low biodegradability and toxicity pose [...] Read more.

Agriculture faces the challenge of transitioning toward sustainable practices, driving the use of plant growth-promoting bacteria (PGPB). However, these bacteria suffer critical losses in viability due to environmental stress and drying processes. Although synthetic hydrogels offer protection, their low biodegradability and toxicity pose ecological risks, positioning dextran hydrogels produced by Leuconostoc sp. as a biocompatible biotechnological alternative, despite challenges related to their mechanical stability. The methodology employed consisted of systematic literature mapping in the Scopus database for the period 2010–2026. The search was conducted on 2 May 2026, using a defined search equation, and 447 documents were processed using RStudio (Bibliometrix), VOSviewer, and Plotly Studio to analyze trends and collaboration networks. The results of the systematic mapping reveal an exponentially growing field (R² = 0.998), led by Agricultural Sciences (23.5%) and Biochemistry (16%). China and India dominate scientific output in terms of volume, while Italy and the United States lead in qualitative impact, with researchers such as Cimini, Schiraldi, and Pandey as key references. An evolution is confirmed from the basic characterization of Leuconostoc sp. toward the development of matrices for immobilizing PGPB, reducing viability losses from 6 log to manageable levels of 4 log CFU. Cluster analysis shows a clear trend toward nanotechnology and “smart hydrogels” responsive to multiple stimuli. Finally, strategic gaps were identified in the creation of predictive release models, as well as an urgent need to democratize the technology through low-cost processes, essential aspects for consolidating sustainable precision agriculture. Full article

(This article belongs to the Special Issue Polymers in the Face of Sustainable Development)

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12 pages, 1238 KB

Open AccessArticle

Assessing the Biodegradation of Lignin/PBAT Composites: A Comparative Study of Weight Loss and Mineralization

by Yanyan Dong, Shaochuang Su, Hong Yang, Zixi Han, Dan Huang, Xiaoshuai Han, Mingqiang Zhu and Fangda Zhang

Polymers 2026, 18(16), 2010; https://doi.org/10.3390/polym18162010 - 18 Aug 2026

Viewed by 322

Abstract

Lignin is a promising bio-based filler for poly(butylene adipate-co-terephthalate) (PBAT), yet its true contribution to biodegradation remains unclear—most studies rely on weight loss alone, neglecting CO₂ mineralization and lignin’s antibacterial activity. Here, lignin/PBAT composites with 1 wt% (LP-1) and 3 wt% (LP-2) [...] Read more.

Lignin is a promising bio-based filler for poly(butylene adipate-co-terephthalate) (PBAT), yet its true contribution to biodegradation remains unclear—most studies rely on weight loss alone, neglecting CO₂ mineralization and lignin’s antibacterial activity. Here, lignin/PBAT composites with 1 wt% (LP-1) and 3 wt% (LP-2) lignin are assessed under composting conditions using both weight loss and mineralization rate. Lignin exhibits a dual role: it promotes hydrolytic weight loss (18.3% and 28.6% for LP-1 and LP-2 at 40 days), but significantly inhibits ultimate mineralization (one-year mineralization: 65.71% for pure PBAT vs. 48.74% and 29.53% for LP-1 and LP-2). A negative initial mineralization rate suggests transient antibacterial activity from released phenolic compounds. Lignin increases crystallization temperature (48.4 → 92.6 °C) and T_g (−28.5 → 49.1 °C), with 1% loading largely preserving mechanical properties. These findings demonstrate that weight loss alone is insufficient to assess degradation; mineralization must be included. Appropriate lignin loading enables balanced performance and degradation controllability, offering new insights into lifecycle assessment of green composites. Full article

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29 pages, 4675 KB

Open AccessArticle

Chemometric Organization and Structure–Property Relationships in an Industrial Polypropylene Product Portfolio

by Joaquín Hernández-Fernández, Juan Lopez-Martinez and Jhojan Salcedo-Castellar

Polymers 2026, 18(16), 2009; https://doi.org/10.3390/polym18162009 - 18 Aug 2026

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Abstract

Industrial polypropylene portfolios comprise multiple commercial grades differentiated by molecular architecture, phase morphology, processability, and performance. In this study, 81 industrial polypropylene grades, including 38 homopolymers, 21 random copolymers, and 22 impact copolymers, were analyzed to evaluate the chemometric organization and structure–property relationships [...] Read more.

Industrial polypropylene portfolios comprise multiple commercial grades differentiated by molecular architecture, phase morphology, processability, and performance. In this study, 81 industrial polypropylene grades, including 38 homopolymers, 21 random copolymers, and 22 impact copolymers, were analyzed to evaluate the chemometric organization and structure–property relationships of a complete commercial portfolio. The dataset integrated melt flow index, xylene-soluble fraction, total ethylene content, ethylene content of the rubber phase, rubber-phase fraction, and mechanical, thermal, and optical performance variables obtained from routine industrial quality-control and product-certification activities. Principal component analysis, partial least squares discriminant analysis, and variable importance in projection analysis were used to examine portfolio organization, evaluate consistency with the predefined polypropylene families, and identify the descriptors contributing most strongly to family-level discrimination. The first two principal components explained 83.8% of the total variance. They revealed a low-dimensional organization consistent with the molecular and morphological differences among homopolymer, random copolymer, and impact copolymer grades. The full-descriptor PLS-DA model achieved 98.8% cross-validated accuracy and correctly classified 80 of the 81 grades using two latent variables. This performance reflects the internal consistency between the descriptor matrix and the existing industrial family classification rather than independently validated predictive capability for unknown grades. Homopolymer differentiation was mainly associated with molecular-weight-related flow behavior, random copolymer organization with ethylene-induced modification of crystallinity, and impact copolymer differentiation with heterophasic rubber-phase characteristics. The results provide a portfolio-specific chemometric workflow for grade organization and structure–property interpretation. However, the numerical domain boundaries and their transferability require validation using independent polypropylene portfolios from other producers. Full article

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

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20 pages, 5243 KB

Open AccessArticle

Long-Term Thermo-Oil Conditioning of PA66-GF25: Non-Monotonic Tensile Response Under Combined Thermal and Lubricant Exposure

by Ronald Bastovansky, Robert Kohar, Rudolf Madaj and Peter Weis

Polymers 2026, 18(16), 2008; https://doi.org/10.3390/polym18162008 - 18 Aug 2026

Viewed by 363

Abstract

Polyamide 66 reinforced with 25 wt.% short glass fibres (PA66-GF25) is widely used in engineering applications requiring long-term operation under combined thermal and lubricated conditions, including polymer bearing cage applications. However, the long-term evolution of its mechanical behaviour under thermo-oil exposure remains insufficiently [...] Read more.

Polyamide 66 reinforced with 25 wt.% short glass fibres (PA66-GF25) is widely used in engineering applications requiring long-term operation under combined thermal and lubricated conditions, including polymer bearing cage applications. However, the long-term evolution of its mechanical behaviour under thermo-oil exposure remains insufficiently documented, particularly over extended exposure periods relevant for service-oriented durability assessment. This study investigates the tensile behaviour of PA66-GF25 after immersion in an industrial bearing lubricant for up to 12 months at conditioning temperatures of −30 °C, 24 °C, and 60 °C. Tensile tests were primarily performed at 24 °C to evaluate the influence of conditioning history, while selected specimens were additionally tested at 60 °C to assess the effect of testing temperature. The results indicate that conditioning temperature strongly influences the evolution of tensile behaviour. Specimens thermo-oil-conditioned at 24 °C and −30 °C exhibited a non-monotonic evolution of tensile strength, characterised by an initial reduction after 4 months followed by recovery and an apparent tendency towards stabilisation at longer exposure durations. In contrast, specimens thermo-oil-conditioned at 60 °C exhibited a continuous increase in tensile strength throughout the investigated period. Although elevated testing temperatures reduced the absolute tensile strength, the relative trends associated with thermo-oil conditioning remained observable. The findings indicate that long-term thermo-oil exposure of PA66-GF25 does not necessarily lead to continuous degradation of tensile performance under the investigated conditions. Instead, the material exhibits a transient response at intermediate exposure durations followed by recovery or an apparent tendency towards stabilisation of tensile performance. These results provide a long-term experimental tensile dataset for PA66-GF25 under combined thermal and lubricant exposure conditions and highlight the importance of extended conditioning when evaluating material performance for lubricated engineering applications. The findings show that intermediate exposure data may not be sufficient for assessing long-term tensile behaviour. However, the mechanisms responsible for the observed tensile strength evolution require further verification using complementary physicochemical and microstructural analyses. Full article

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

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24 pages, 5990 KB

Open AccessEditor’s ChoiceArticle

Meniscus Morphology-Based Prediction of Backup Roll Eccentricity for Stable Slot-Die Coating on Polymer Films

by Mingi Kim, Chanwoo Kim, Jeongdai Jo, Byungho Park and Changwoo Lee

Polymers 2026, 18(16), 2007; https://doi.org/10.3390/polym18162007 - 17 Aug 2026

Viewed by 1214

Abstract

In roll-to-roll slot-die coating systems, backup roll eccentricity induces periodic fluctuations in key process parameters, leading to coating defects. Therefore, accurate prediction of backup roll eccentricity during operation is essential for maintaining stable coating quality. However, conventional methods based on web tension signals [...] Read more.

In roll-to-roll slot-die coating systems, backup roll eccentricity induces periodic fluctuations in key process parameters, leading to coating defects. Therefore, accurate prediction of backup roll eccentricity during operation is essential for maintaining stable coating quality. However, conventional methods based on web tension signals have limitations in clearly distinguishing and quantitatively evaluating subtle eccentricities. To address this issue, this study proposes a data-driven framework for predicting backup roll eccentricity using meniscus image information. Representative morphological features are defined to describe the global shape, local shape, and curvature characteristics of the meniscus. Since these features are sensitive to eccentricity-induced process variations, they can serve as effective indicators for eccentricity prediction. The defined features are used to train regression models, and the model with the highest predictive accuracy is selected. Experimental results confirm that the proposed meniscus-based approach significantly outperforms conventional tension-based methods. The proposed method achieves an average Root Mean Square Error (RMSE) of approximately 0.63 μm, an average Normalized Root Mean Square Error (NRMSE) of approximately 0.34, and a coefficient of determination (R²) greater than 0.93 across all test cases. These results demonstrate the feasibility of robust process monitoring using a simple vision sensor configuration. Full article

(This article belongs to the Special Issue Polymer-Based Coatings: Principles, Development and Applications)

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30 pages, 4319 KB

Open AccessArticle

The Influence of Xanthan Gum and Guar Gum Biopolymers on the Geotechnical Properties of Three Different Soils

by Çiğdem Ceylan

Polymers 2026, 18(16), 2006; https://doi.org/10.3390/polym18162006 - 17 Aug 2026

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Abstract

This study investigates the macromolecular interaction mechanisms between linear-anionic xanthan gum (XG) and branched-nonionic guar gum (GG) biopolymers in three mineralogically distinct soils: Bentonite Clay (BC), Zeolite Silty Soil (ZS), and Red Clay (RC). Mıxtures were prepared by dry mixing of soil powders [...] Read more.

This study investigates the macromolecular interaction mechanisms between linear-anionic xanthan gum (XG) and branched-nonionic guar gum (GG) biopolymers in three mineralogically distinct soils: Bentonite Clay (BC), Zeolite Silty Soil (ZS), and Red Clay (RC). Mıxtures were prepared by dry mixing of soil powders with biopolymer powders at designated ratios (0%, 1%, 2%, 3%, and 4% by dry weight). The prepared mixtures were characterized using X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), and standard compaction and shear strength tests. The results show that geotechnical macro-behavior is primarily influenced by polymer chain conformation and mineral interfacial reactions. In ZS-XG mixture, hydraulic conductivity increased approximately 26-fold (from 0.107 × 10⁻⁹ to 2.83 × 10⁻⁹ m/s), a phenomenon attributed to the Donnan electrostatic exclusion effect, where linear anionic XG chains repel zeolite surfaces and generate low-friction macro-flow paths. Conversely, the addition of GG to RC formed a strongly interconnected hydrogel network through hydrogen bonding with trivalent iron and magnesium oxides, resulting in a 20.8% increase in cohesion (up to 70.05 kPa). In contrast, GG addition decreased cohesion in BC and ZS. These findings confirm that sustainable biopolymer-based soil remediation depends on customizing the polymer morphology according to the properties of the soil. In engineering applications, ZS-XG mixtures should be evaluated for drainage projects requiring high permeability, whereas the RC-GG4 mixture should be considered a primary option for infiltration barriers (e.g., landfill liners) requiring low permeability and high cohesion. Full article

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

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Polymers, Volume 18, Issue 16 (August-2 2026) – 106 articles

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