Polymers

16 pages, 3122 KB

Open AccessArticle

Enhancing Separation Performance of PA Nanofiltration Membrane Through Polyelectrolyte PSS Interlayer and Surface Modification

by Fotios Panagiotou, Georgia Zafeiropoulou, Franceska Gojda, Kiriaki Chrissopoulou, Ioannis Zuburtikudis and Valadoula Deimede

Polymers 2026, 18(10), 1242; https://doi.org/10.3390/polym18101242 - 19 May 2026

Abstract

Thin-film composite (TFC) polyamide (PA) nanofiltration membranes are the state of the art for water purification and reclamation, although a selectivity–permeability trade-off often restricts their development. To mitigate this problem, in this work, a novel three-layer structured nanofiltration (NF) membrane was fabricated consisting [...] Read more.

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

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

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24 pages, 3046 KB

Open AccessArticle

Biomimetic Core–Sheath GelMA/PCL Nanofibers for Enhanced Peripheral Nerve Regeneration

by Xingxing Fang, Haichang Guo, Fei Yu, Wei Zhang, Qicheng Li, Shulin Bai and Peixun Zhang

Polymers 2026, 18(10), 1241; https://doi.org/10.3390/polym18101241 - 19 May 2026

Abstract

Artificial nerve guidance conduits (NGCs) have gained significant attention in the field of peripheral nerve regeneration for the treatment of critically sized nerve defects. Nanotechnology-based NGCs are being explored as potential solutions for repairing and reconstructing peripheral nerve injuries due to their unique [...] Read more.

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

(This article belongs to the Special Issue Advanced Polymer Processing for Tissue Engineering)

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36 pages, 5169 KB

Open AccessArticle

A Statistically Grounded and Physics-Aware Vision Framework for Detecting Barely Visible Impact Damage (BVID) in Heterogeneous Polymer-Matrix Composites

by Gönenç Duran

Polymers 2026, 18(10), 1240; https://doi.org/10.3390/polym18101240 - 19 May 2026

Abstract

Barely Visible Impact Damage (BVID) in heterogeneous polymer-matrix composites remains difficult to detect because subtle damage signatures are often masked by complex architectures, hybrid textures, and overlapping failure morphologies. This study therefore presents an experimentally grounded, physics-aware, and statistically validated vision-based inspection framework [...] Read more.

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

(This article belongs to the Special Issue Artificial Intelligence in Polymers)

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35 pages, 16323 KB

Open AccessArticle

Osteoinductive and Biocompatibility Assessment of a 3D-Printed Polymeric–Hydroxyapatite Composite Interference Screw

by Rana Smaida, Louis-Paul Maugard, Hervé Gegout, Manuel Arruebo, Florence Fioretti, Nadia Benkirane-Jessel and Henri Favreau

Polymers 2026, 18(10), 1239; https://doi.org/10.3390/polym18101239 - 19 May 2026

Abstract

Anterior cruciate ligament reconstruction relies on interference screw fixation, yet insufficient graft osseointegration remains a critical clinical challenge. This study aimed to develop and characterize a 3D-printed polymeric–hydroxyapatite composite interference screw with an osteoinductive surface to enhance localized osteogenic responses. Screws were designed, [...] Read more.

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

(This article belongs to the Special Issue 3D Printing Polymer Materials and Their Biomedical Applications—2nd Edition)

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29 pages, 17904 KB

Open AccessReview

Interphase Engineering in Lignin-Containing Nanocellulose Composites from Tropical Biomass: Evidence-Weighted Comparative Framework, Product Windows, and Biorefinery Constraints

by José Roberto Vega-Baudrit and Mary Lopretti

Polymers 2026, 18(10), 1238; https://doi.org/10.3390/polym18101238 - 19 May 2026

Abstract

Tropical lignocellulosic residues are increasingly relevant feedstocks for lignin-containing nanocellulose composites, but their performance cannot be predicted from botanical origin or bulk lignin percentage alone. This review defines the interface as the geometrical boundary between phases and the interphase as the finite, compositionally [...] Read more.

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

(This article belongs to the Special Issue Advanced Study on Lignin-Containing Composites)

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16 pages, 3675 KB

Open AccessArticle

Chitosan-Modified Coconut Shell Activated Carbon for Efficient Hexavalent Chromium Removal from Aqueous Solution

by Danyun Lei, Weiyi She, Xiaoyu Chen, Lei You, Ying Zheng and Byoung-Suhk Kim

Polymers 2026, 18(10), 1237; https://doi.org/10.3390/polym18101237 - 19 May 2026

Abstract

Chitosan (CS) was employed to modify coconut shell activated carbon (CAC) to fabricate a composite adsorbent for wastewater treatment. By integrating the functional groups of CS with the high specific surface area of CAC through chemical modification, the resulting CS-AC composite exhibited significantly [...] Read more.

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

(This article belongs to the Special Issue Polymeric Materials for Wastewater Treatment Applications, 2nd Edition)

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18 pages, 3950 KB

Open AccessArticle

Wetting Behavior of Acrylate Hot-Melt Adhesive on Polyester Fabric Substrates and Its Influence on Adhesion Performance

by Haoran Shi, Jun Qian and Yifeng Shi

Polymers 2026, 18(10), 1236; https://doi.org/10.3390/polym18101236 - 19 May 2026

Abstract

Acrylate hot-melt adhesives (AHMAs) are widely used in medical dressings, electronic components, and automotive interiors due to their solvent-free nature and high bonding strength. However, their wetting behavior on porous fabric substrates under varying coating temperatures—a critical factor for interfacial adhesion—remains poorly understood. [...] Read more.

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

(This article belongs to the Special Issue Surface and Interface Analysis of Polymeric Materials)

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21 pages, 2206 KB

Open AccessReview

Lignocellulosic Biomass-Based Metal–Organic Frameworks: A Sustainable Frontier for Advanced Wastewater Remediation

by Aparna Sudarsana Babu, Florian Zikeli and Debora Puglia

Polymers 2026, 18(10), 1235; https://doi.org/10.3390/polym18101235 - 19 May 2026

Abstract

The emerging demand for water pollution control has driven a significant interest in advanced porous materials for sustainable and effective wastewater treatment technologies. Metal–organic frameworks (MOFs) have been employed as promising substrates due to their versatile properties, especially their high surface area, tunable [...] Read more.

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

(This article belongs to the Special Issue Life Cycle and Utilization of Lignocellulosic Materials)

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44 pages, 4319 KB

Open AccessReview

Concise Review of Corrective Responsive Food Packaging: Recent Advances and Future Prospects

by Hailin Wang, Haowei Lv, Boliang Li, Linyan Deng, Yangyang Wen and Hongyan Li

Polymers 2026, 18(10), 1234; https://doi.org/10.3390/polym18101234 - 18 May 2026

Abstract

Food packaging constitutes a pivotal enabler within the contemporary food industry, requiring continuous innovation to address evolving challenges. Traditional packaging systems typically provide passive protection, which is inadequate for addressing dynamic microbial shifts and spoilage-induced microenvironmental instabilities. In contrast, corrective responsive food packaging [...] Read more.

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

(This article belongs to the Special Issue Sustainable Polymer for Green Packaging Application)

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23 pages, 8253 KB

Open AccessArticle

Mechanical Performance of Novel 3D-Printed Symmetric Corrugated Hierarchical Honeycombs

by Derui Zhang, Junpeng Ma, Long Liu, Yan Zhu, Anfu Guo, Peng Qu, Shuai Guo, Zengrui Song, Yaqin Song and Shaoqing Wang

Polymers 2026, 18(10), 1233; https://doi.org/10.3390/polym18101233 - 18 May 2026

Abstract

Symmetric corrugated hierarchical honeycombs (SCHHs) are critical lightweight load-bearing structures, featuring distinctive topological architectures and excellent mechanical performance. However, they are prone to local buckling under out-of-plane compression and shear loading, which degrades their overall load-bearing capacity. To address this limitation, this work [...] Read more.

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

(This article belongs to the Special Issue 3D Printing of Polymer Composite Materials—Advances in Materials and Processes)

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16 pages, 2209 KB

Open AccessArticle

Improved Viscoelastic Numerical Simulation and In Situ Dynamic FBG Sensing of Interfacial Curing Stress Concentration in Epoxy Insulation Materials

by Zhen Li, Zhiyun Han, Xinkai Zhang, Yizhou Xu, Liang Zou, Kejie Huang and Hanwen Ren

Polymers 2026, 18(10), 1232; https://doi.org/10.3390/polym18101232 - 18 May 2026

Abstract

Interfacial stress concentration induced by curing shrinkage during the manufacturing of epoxy resin is a primary trigger for micro-nano defect formation and electrical performance degradation in power equipment. To address the computational complexity of traditional viscoelastic models and the thermoelastic behavior wherein the [...] Read more.

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

(This article belongs to the Section Polymer Applications)

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23 pages, 1951 KB

Open AccessArticle

Electron Beam Irradiation for Impact Strength Enhancement of Kevlar Fiber-Reinforced Polypropylene

by Hideki Kimura, Yusuke Kobayashi, Hirotaka Irie, Kouhei Sagawa, Helmut Takahiro Uchida, Michael C. Faudree, Michelle Salvia and Yoshitake Nishi

Polymers 2026, 18(10), 1231; https://doi.org/10.3390/polym18101231 - 18 May 2026

Abstract

Presently, there is little to no literature that investigates the effect of electron beams on para-aramid (Kevlar^®) fiber polymer (KFRP) composites. Therefore, we assessed the effect of homogeneous low-potential electron beam irradiation (HLEBI) on Kevlar-reinforced recyclable thermoplastic (TP) polypropylene (PP) (KFRPP). [...] Read more.

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

(This article belongs to the Special Issue Advanced Polymer Composites: Structure and Mechanical Properties)

19 pages, 1322 KB

Open AccessArticle

Compound-Resolved VOC Dynamics in a Full-Scale Medium-Density Fibreboard Dryer: Process–State Screening Across Wood Furnish, Amino Resin Dosing, and Thermal Operating Variables

by Vladimir Nedić, Andreas Paul, Marius Catalin Barbu and Lubos Kristak

Polymers 2026, 18(10), 1230; https://doi.org/10.3390/polym18101230 - 18 May 2026

Abstract

Industrial control of volatile organic compound (VOC) emissions from medium-density fibreboard (MDF) production remains constrained by a shortage of compound-resolved evidence from full-scale plants, where wood furnish, amino resin chemistry, heat transfer, gas flow, and wet gas cleaning act simultaneously. Here, we analysed [...] Read more.

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

(This article belongs to the Special Issue Advances in Wood and Wood Polymer Composites)

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22 pages, 20929 KB

Open AccessArticle

Production of Green Synthesized Zinc Oxide Nanoparticle-Reinforced PMMA-Based Photopolymer Resins on DLP-Based 3D Printers and Characterization

by Behiç Selman Erdoğdu, Muhammed İhsan Özgün, Emrah Madenci, Mehmet Ali Sayınbatur and Fatih Erci

Polymers 2026, 18(10), 1229; https://doi.org/10.3390/polym18101229 - 18 May 2026

Abstract

In this study, the structural, thermal, and mechanical properties of nanocomposites obtained by adding zinc oxide (ZnO) nanoparticles (NPs), produced by phyto-mediated synthesis using Dianthus chinensis plant extract, to a PMMA-based photopolymer resin at different ratios (0.05%, 0.10%, 0.15%, 0.20%, and 0.25%, by [...] Read more.

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

(This article belongs to the Special Issue 3D Printing of Polymer Composite Materials—Advances in Materials and Processes)

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26 pages, 10861 KB

Open AccessArticle

Static and Dynamic Compressive Properties of Nano-Al₂O₃-Reinforced Epoxy Matrix Composites

by Jinzhu Li, Liwei Zhang and Jinchao Qiao

Polymers 2026, 18(10), 1228; https://doi.org/10.3390/polym18101228 - 17 May 2026

Abstract

This study investigates the influence of nano-alumina (nano-Al₂O₃) on the compressive properties and damage mechanisms of epoxy matrix composites across a wide strain rate range. Composites with varying nano-Al₂O₃ contents (0, 1, 3, 5, 10, 15 [...] Read more.

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

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

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22 pages, 3109 KB

Open AccessArticle

Cellulose-Based Polymer Blends for Oral Mucoadhesion: Impact of Hydration and Surface Interactions

by Monika Rojewska, Emilia Jakubowska, Klaudia Szelejewska, Maja Nowaczyk, Anna Froelich, Krystyna Prochaska and Tomasz Osmałek

Polymers 2026, 18(10), 1227; https://doi.org/10.3390/polym18101227 - 17 May 2026

Abstract

Hydration, interfacial interactions, and matrix stability are critical determinants of the mucoadhesive behavior of cellulose-based polymers. In this study, we investigated the physicochemical and mucoadhesive behavior of hydroxypropyl methylcellulose (HPMC), Carbopol 974P NF, and Kollidon VA 64, along with their binary blends (1:1, [...] Read more.

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

(This article belongs to the Special Issue Advances in Polymer Based, Structured Liquid Systems)

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15 pages, 7069 KB

Open AccessArticle

Mechanically Enhanced and Reprocessable Vanillin-Based Epoxy Resin via Synergistic Effect of Rigid Cross-Linked Networks and Alkyl Dangling Chains

by Likang Zhou, Songjie Xu, Junhao Fei, Meng Ma, Huiwen He, Yanqin Shi, Yulu Zhu, Si Chen and Xu Wang

Polymers 2026, 18(10), 1226; https://doi.org/10.3390/polym18101226 - 17 May 2026

Abstract

The cross-linked network structure of epoxy resins gives them excellent mechanical properties and heat resistance. However, it also makes them difficult to reprocess and recycle. This leads to environmental pollution and resource waste. Dynamic covalent bonds can make epoxy resins reprocessable. However, this [...] Read more.

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

(This article belongs to the Special Issue Synthesis, Characterization and Environmental Assessment of Novel Polymeric Materials for Sustainable Applications)

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25 pages, 4170 KB

Open AccessArticle

Scalable AC Electrospinning of Biocompatible Nanofibrous Yarns Based on Expanded Graphite and PEDOT:PSS

by Divan Coetzee, Juan Pablo Perez Aguilera, Jakub Wiener and Jiří Militký

Polymers 2026, 18(10), 1225; https://doi.org/10.3390/polym18101225 - 17 May 2026

Abstract

This study presents the development of biocompatible antistatic nanofibrous composite yarns via a scalable AC electrospinning method, incorporating ultrasonicated expanded graphite (uEG) and PEDOT:PSS into polyamide (PA), polyvinyl butyral (PVB), and polyvinyl alcohol (PVA) matrices. TGA confirmed high filler retention during electrospinning. Electrical [...] Read more.

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

(This article belongs to the Special Issue Recent Advances in Electrospun Polymer Nanofibers)

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43 pages, 5122 KB

Open AccessReview

Bioinspired Polymeric Scaffolds for Improvement of Angiogenesis and Tissue Engineering: A Review

by Vyas Jigar, Raytthatha Nensi, Vyas Puja, Bhupendra Prajapati, Pattaraporn Panraksa, Sudarshan Singh and Chuda Chittasupho

Polymers 2026, 18(10), 1224; https://doi.org/10.3390/polym18101224 - 17 May 2026

Abstract

Poor vascularization is one of the basic obstacles to the regeneration of functioning tissues because an oxygen diffusion process and elimination of wastes are essential in preserving the grafts. Recently, biomaterials have allowed the invention of bioinspired polymer scaffolds and replicated the natural [...] Read more.

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

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Polymers

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