Polymers

21 pages, 15875 KB

Open AccessArticle

Effect of Liquid Smoke Incorporation on the Structural, Barrier, and Functional Properties of Okra Mucilage–Corn Starch Films

by Nayanne Lima Dos Santos Ferreira, Luana Kelly Sampaio Facundo, Maryana Melo Frota, Maria Do Socorro Rocha Bastos, Lorena Maria Freire, Kaliana Sitônio Eça, Jeanlex Soares de Sousa, João Borges Laurindo, Thomas Karbowiak, Patrícia Marques De Farias, Markus Schmid and Luciana De Siqueira Oliveira

Polymers 2026, 18(13), 1566; https://doi.org/10.3390/polym18131566 (registering DOI) - 23 Jun 2026

Abstract

The present study investigated the effect of liquid smoke (LS) on the physicochemical, structural, barrier, and functional properties of okra mucilage–corn starch (OMCS) films. Formulations containing varying concentrations of LS (0–3%) were prepared using the casting method. The incorporation of LS modified the [...] Read more.

The present study investigated the effect of liquid smoke (LS) on the physicochemical, structural, barrier, and functional properties of okra mucilage–corn starch (OMCS) films. Formulations containing varying concentrations of LS (0–3%) were prepared using the casting method. The incorporation of LS modified the rheological behavior of the film-forming dispersions, as evidenced by increased apparent viscosity and consistency index. In the films, water solubility increased from 43.6 to 53.2%, contact angle increased from 31.9° to 55.6°, and opacity increased from 4.73 to 8.83, while water vapor permeability decreased from 1.05 to 0.88 g·mm·m⁻²·h⁻¹·kPa⁻¹, indicating modifications in matrix organization and surface hydrophobicity. Tensile strength increased from 26.3 to 40.5 MPa at 3% LS, accompanied by a slight reduction in elongation, suggesting enhanced structural rigidity. Structural analyses revealed interactions between the LS phenolic compounds and the polysaccharide hydroxyl groups, resulting in a more cohesive polymeric network. LS was the main contributor to the film’s antioxidant activity owing to its elevated phenolic content and free radical scavenging capacity. The films also showed substantial degradation under soil burial conditions, with mass loss ranging from 61% to 96%. Overall, LS proved to be an effective functional additive, improving the structural and antioxidant performance of OMCS films and expanding their potential for active food packaging applications. Full article

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

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26 pages, 2833 KB

Open AccessReview

Recent Advances in Cellulose Depolymerization: Mechanistic Insights, Catalytic Innovations, and Scalable Pathways for Biomass Valorization

by Marián Lehocký

Polymers 2026, 18(13), 1565; https://doi.org/10.3390/polym18131565 (registering DOI) - 23 Jun 2026

Abstract

Cellulose is the most promising abundant renewable polymer material with the highest potential for the future low-carbon biorefineries. However, its utilization in industry is limited by the structural recalcitrance as a result of organization of crystalline domains, fibrillar architecture hierarchy and intramolecular and [...] Read more.

Cellulose is the most promising abundant renewable polymer material with the highest potential for the future low-carbon biorefineries. However, its utilization in industry is limited by the structural recalcitrance as a result of organization of crystalline domains, fibrillar architecture hierarchy and intramolecular and intermolecular hydrogen bonding which is responsible for access restriction for the catalysts and consequent cleavage of the glycosidic bonds. Therefore, efficient depolymerization of cellulose is of paramount importance as a step in biomass conversion into the low molecular products. In this review, the recent advances in cellulose depolymerization are discussed. The chemical, enzymatic, thermal, thermochemical, mechanochemical, oxidative and hybrid catalytic method is thoroughly discussed. Attention is paid to the mechanism of the depolymerization reaction steps as glycosidic bond activation as hydrolytic, radical mediated, and energy assisted pathways. Selectivity and conversion efficiency based on substrate morphology, solvent system and catalyst design are also discussed. Further, there is a comparison of key performance metrics which are relevant for the industrial process as product yield, carbon efficiency, energy demand, stability of the catalyst, solvent recyclability and impact to the environmental lifecycle. The pros and cons of the various methods are also represented. Processes based on mineral acids enable rapid conversion. However, they suffer from corrosion, waste handling issues and degradation by-products. On the other hand, enzymatic depolymerization processes offer relatively high selectivity but they are limited in terms of feedstock sensitivity and slow reaction kinetics. The downstream valorization mechanisms are also described with the result being that no single available technology is capable of satisfying all industrial requirements. Thus, future progress expects integrated circular processes where advanced catalysis, process intensification and digital optimization strategies take place. Full article

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

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16 pages, 520 KB

Open AccessArticle

Production of Motor Gasoline Components from Plastic Waste by Pyrolysis Followed by Hydrosaturation of Fuel Fractions

by Andrey Altynov, Daniil Eronskiy, Maria Kirgina, Kirill Larionov and Ilya Bogdanov

Polymers 2026, 18(13), 1564; https://doi.org/10.3390/polym18131564 (registering DOI) - 23 Jun 2026

Abstract

In the context of a constantly deteriorating environmental situation, in particular due to the uncontrolled accumulation of plastic waste, the search for effective ways to recycle plastic is an urgent task. Pyrolysis of plastic waste followed by the hydrosaturation of liquid products may [...] Read more.

In the context of a constantly deteriorating environmental situation, in particular due to the uncontrolled accumulation of plastic waste, the search for effective ways to recycle plastic is an urgent task. Pyrolysis of plastic waste followed by the hydrosaturation of liquid products may become a promising method for obtaining components of motor gasoline. The aim of this study is to obtain motor gasoline components from plastic waste through pyrolysis, followed by hydrogenation of the fuel fractions for their use in the production of commercial fuels. The scientific novelty of this study consists of establishing the influence of hydrosaturation process parameters on an Al-Co-Mo hydrotreating catalyst (temperature and feedstock flow rate) on the transformation of hydrocarbons present in the gasoline fraction separated from the liquid pyrolysis products of polypropylene waste. The most preferred conditions for obtaining feedstock for subsequent hydrosaturation of polypropylene waste turned out to be the pyrolysis process carried out at a temperature of 450 °C and atmospheric pressure. Based on calculations in the Compounding software, promising blending components were identified. Based on the obtained results, two samples were identified as having the greatest potential for blending commercial gasolines in terms of hydrocarbon composition and performance characteristics. The sample obtained at the hydrosaturation process parameters of 350 °C and a feedstock flow rate of 0.51 mL/min is the most preferable in terms of its composition, since it demonstrates a minimal content of olefins (18.7 % vol.) and benzene (0.87 % vol.) but has a relatively low octane number (RON 58.7). The sample obtained at the hydrosaturation process parameters of 300 °C and a feedstock flow rate of 0.85 mL/min has relatively higher octane characteristics (RON 72.9) and can be used as a high-octane component but requires blending with components that compensate for the increased olefin content. Also, it is shown in this work that hydrosaturation of the gasoline fraction separated from the liquid pyrolysis products of polypropylene waste enables the production of motor gasoline components whose blending rate in commercial gasolines recipes can reach up to 35 % by volume. Full article

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

28 pages, 6209 KB

Open AccessArticle

Mechanical, Thermal, and Microstructural Characterization of FDM-Printed PLA/Obsidian Composites

by Fatih Alibeyoglu

Polymers 2026, 18(13), 1563; https://doi.org/10.3390/polym18131563 (registering DOI) - 23 Jun 2026

Abstract

FDM-printed polylactic acid (PLA) composites containing 5 and 10 wt% obsidian powder sourced from the Kars region of Eastern Anatolia (Turkey) were produced via twin-screw masterbatch extrusion and subsequent single-screw filament dilution. Mechanical (tensile, three-point flexure, notched Charpy impact, Shore D), physical (density), [...] Read more.

FDM-printed polylactic acid (PLA) composites containing 5 and 10 wt% obsidian powder sourced from the Kars region of Eastern Anatolia (Turkey) were produced via twin-screw masterbatch extrusion and subsequent single-screw filament dilution. Mechanical (tensile, three-point flexure, notched Charpy impact, Shore D), physical (density), thermal (simultaneous TGA/DSC) and microstructural (macroscopic fractography and SEM at 100×–1000×) characterizations were performed on FDM-printed specimens. Young’s modulus rose monotonically by +9.0% at 5 wt% and +18.2% at 10 wt%, while ultimate tensile strength decreased by 12.4% and 17.3%, respectively. The flexural modulus increased by +15.2% at 5 wt% and plateaued at 10 wt% (+16.7%), whereas the flexural strength decreased by only 3.5% at 10 wt%, indicating that flexure-mode loading is markedly more tolerant of obsidian filler than axial tension. Shore D hardness rose by +2.11 points from 0 to 5 wt% with saturation thereafter. TGA showed a dual thermal effect: T₅ and T₁₀ dropped by 5–6 °C from 5 to 10 wt%, while the main decomposition rate decreased by ~46% and the decomposition interval widened from 9.7 to 23.5 °C, indicating a barrier/heat-shielding effect of dispersed silicate particles. SEM revealed a continuous ductile → transitional → brittle progression with increasing obsidian content; extended interfacial debonding lines at 10 wt% identified weak unmodified filler/matrix coupling as the principal performance-ceiling factor. Density measurements indicated a ~3–6% residual void fraction consistent with the inter-bead voids observed by SEM. To the authors’ knowledge, this is the first systematic study of obsidian as a reinforcing filler in PLA; the 5 wt% composition is identified as a strong candidate for esthetic, flexure-dominant, and low-load structural applications. Full article

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

22 pages, 9530 KB

Open AccessArticle

Enhanced Bone-Defect Regeneration Through nHA/Chitosan Nanocomposite-Facilitated Delivery of HUCB-MSCs-Derived Exosomes

by Lingzhi Ding, Jiachen Liu, Jia Gao, Yongqian Fu, Wenhui Chu and Shunwu Fan

Polymers 2026, 18(13), 1562; https://doi.org/10.3390/polym18131562 (registering DOI) - 23 Jun 2026

Abstract

Critical-sized bone defects lack spontaneous healing capacity. While mesenchymal stem cell-derived exosomes (sEVs) are promising osteoinductive agents, their rapid in vivo clearance limits their free-form efficacy. Here, we fabricated a nano-hydroxyapatite/chitosan (nHA/CTS) composite scaffold as a protective, sustained-delivery platform for human umbilical cord [...] Read more.

Critical-sized bone defects lack spontaneous healing capacity. While mesenchymal stem cell-derived exosomes (sEVs) are promising osteoinductive agents, their rapid in vivo clearance limits their free-form efficacy. Here, we fabricated a nano-hydroxyapatite/chitosan (nHA/CTS) composite scaffold as a protective, sustained-delivery platform for human umbilical cord blood-derived mesenchymal stem cell exosomes (HUCB-MSCs-exos) to accelerate bone repair. The 3D porous CTS/10% nHA scaffold exhibited excellent cytocompatibility and a degradation rate commensurate with new bone ingrowth. Critically, it enabled a biphasic exosome release profile—an initial burst followed by a 14-day sustained release (89.73% cumulative release). In vitro, HUCB-MSCs-exos significantly promoted the proliferation, migration, and osteogenic differentiation of bone marrow-derived MSCs, as demonstrated by enhanced alkaline phosphatase activity and matrix mineralization. In a rabbit condylar defect model (5 mm diameter), the CTS/10% nHA-exo scaffold achieved a 57.44 ± 8.42% healing rate at two months, nearly two-fold greater than the scaffold-only group (29.33 ± 6.94%). Histological and immunohistochemical analyses at two months confirmed the formation of mature, well-vascularized trabecular bone, accompanied by robust expression of late-stage osteogenic markers (OCN and OPN). These findings demonstrate that the CTS/10% nHA scaffold synergistically integrates osteoconductive structural guidance with exosome-mediated osteoinductive paracrine signaling, providing a compelling and translatable strategy for critical-sized bone-defect management. Full article

(This article belongs to the Special Issue Chitosan and Its Composite Materials for Biomedical Applications)

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24 pages, 11542 KB

Open AccessArticle

Novel Silicone Rubber–Based Multi-Dimensional Filler Composite Electrode Materials for the Dielectric Elastomer Actuation Technology of Micro-Crawling Robots

by Yang Hong, Yun Yang, Zening Lin, Tao Jiang and Zirong Luo

Polymers 2026, 18(13), 1561; https://doi.org/10.3390/polym18131561 (registering DOI) - 23 Jun 2026

Abstract

Aiming to develop high-performance flexible electrode materials for dielectric elastomer actuation systems applied to micro-crawling robots, this study proposes multi-dimensional filler composite electrode materials with a methyl vinyl silicone rubber matrix. Three types of conductive fillers—namely, zero-dimensional super-conductive carbon black, one-dimensional single-walled carbon [...] Read more.

Aiming to develop high-performance flexible electrode materials for dielectric elastomer actuation systems applied to micro-crawling robots, this study proposes multi-dimensional filler composite electrode materials with a methyl vinyl silicone rubber matrix. Three types of conductive fillers—namely, zero-dimensional super-conductive carbon black, one-dimensional single-walled carbon nanotubes, and two-dimensional flaky micron-sized silver powder—were employed to construct a hierarchical multi-dimensional conductive network within the silicone rubber matrix via a three-stage fabrication strategy. The electrical conductivity and conductive stability of the as-prepared composite electrode materials were systematically investigated, where the intrinsic mechanisms and evolutionary laws of material electrical performance variations were analyzed. Furthermore, the effects of fillers with different dimensional morphologies on the comprehensive properties of the composites at each fabrication stage were explored, and the optimal filler dosage for each component was determined. Microstructural observations of the staged conductive network formation further verified the rationality of the stage-based functional design model. The optimized composite electrode delivers an initial electrical conductivity of 1.5 × 10⁴ S/m, with only a 14.9% conductivity attenuation under 50% tensile strain, demonstrating excellent electromechanical stability. Moreover, a prototype micro-crawling robot was fabricated using the optimized composite electrode, achieving a maximum linear crawling speed of 8 mm/s. These experimental results validate the feasibility and superiority of the proposed multi-dimensional filler composite strategy. This work provides a novel technical approach for the design and development of high-performance flexible electrode materials for flexible electronic and micro-robotic actuation applications. Full article

(This article belongs to the Section Smart and Functional Polymers)

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17 pages, 14220 KB

Open AccessArticle

Experimental and Theoretical Studies on Enhanced Lubricity of Hyperbranched Polyamide-Amine for Water-Based Drilling Fluids

by Wei Wang, Rongsheng Lin, Lin Xu, Zhujun Zhang, Lei Wang, Siqi Yang, Wuwei Feng, Peng Xu and Meilan Huang

Polymers 2026, 18(13), 1560; https://doi.org/10.3390/polym18131560 (registering DOI) - 23 Jun 2026

Abstract

High friction and drag are among the challenging subjects for constructing water-based drilling fluids available in horizontal drilling. Lubricants play a major role in mitigating friction of water-based drilling fluids, and thus, developing new lubricants is necessary for efficient horizontal drilling. In this [...] Read more.

High friction and drag are among the challenging subjects for constructing water-based drilling fluids available in horizontal drilling. Lubricants play a major role in mitigating friction of water-based drilling fluids, and thus, developing new lubricants is necessary for efficient horizontal drilling. In this work, a generation 1.5 (1.5G) hyperbranched polyamide-amine P(EDA-MA-OA), which serves as a candidate for a traditional lubricant with linear conformation, was newly synthesized via a divergent approach. A set of physicochemical characterizations was carried out on P(EDA-MA-OA) to confirm its effective synthesis. The results indicated that P(EDA-MA-OA) has a nanoparticulate morphology with a size of approximately 100 nm. Its molecular structure shows strong thermal stability, with initial thermal decomposition occurring at 146 °C. The water-based drilling fluid formulated with P(EDA-MA-OA) as the lubricant exhibits effective comprehensive properties and, in particular, the lubrication coefficient was 0.067, comparable to that of the oil-based drilling fluid, indicating enhanced lubricity by the incorporation of the hyperbranched polymer. The results of molecular simulations show that P(EDA-MA-OA) possesses a unique “basket-like” architecture, with C18 long chains enveloping the central active segments, namely the carbonyl (-C=O) and amide (-CO(NH₂)) groups. When interacting with montmorillonite (MMT) particulates, the active groups can interact with MMT, allowing the eight C18 branched terminal chains to form a “molecular brush” with a normal orientation toward the MMT interface, which can serve as a hydrophobic lubricating film to improve lubricity. A lubrication model was finally proposed to rationalize the enhanced lubricity from the hyperbranched polymers in the water-based drilling fluid. Full article

(This article belongs to the Special Issue Polymer Science in Petroleum Engineering: Latest Trends and Developments, 2nd Edition)

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36 pages, 5697 KB

Open AccessArticle

Machine Learning Prediction of Thermal Properties of PHB/PHBV-Based Materials: A Quantitative Structure–Property Relationship Approach Using an Integrated Polymer Database

by Nikolaos P. Sotiropoulos, Leonidas Mindrinos, Jean-David Peltier, Konstantina V. Filippou, Marianna I. Kotzabasaki, Nikolaos Tsigkas and Chrysanthos Maraveas

Polymers 2026, 18(13), 1559; https://doi.org/10.3390/polym18131559 (registering DOI) - 23 Jun 2026

Abstract

Bio-based and biodegradable polymers such as short-chain-length (scl) poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) are widely adopted in diverse areas such as healthcare, manufacturing, and packaging. However, high production costs and the complexity of tailoring their thermal properties, such as glass transition temperature (Tg), [...] Read more.

Bio-based and biodegradable polymers such as short-chain-length (scl) poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) are widely adopted in diverse areas such as healthcare, manufacturing, and packaging. However, high production costs and the complexity of tailoring their thermal properties, such as glass transition temperature (Tg), melting temperature (Tm), and crystallization temperature (Tc), hinder further adoption. The current study reported on the development of a raw dataset of PHB and PHBV materials compiled from 572 instances collected from the literature (558 instances) and in-house experiments (14 instances). The dataset encompassed compositional physicochemical parameters, molecular features, and corresponding thermal characteristics. After assessing data quality and filtering for completeness and available features, curated datasets were created for machine learning (ML) analysis. Two ML models, Random Forest (RF) and eXtreme Gradient Boosting (XGBoost), were utilized to predict values of Tg, Tc, and Tm using feature engineering methods that integrated chemistry-based descriptors with polymer-specific and experimental variables. The predictive performance of the models was systematically investigated using different combinations of input features to identify the most informative descriptor sets for each target property. The best-performing models were obtained using 118 data points for Tg and Tm and 201 data points for Tc, achieving R² values of 0.77, 0.76, and 0.82 for Tg, Tc, and Tm, respectively. Despite the reliable prediction of the thermal properties of scl-PHAs, the main limitations of the study were the relatively small dataset size for certain targets and incomplete or missing reporting of experimental conditions in the literature sources, which may introduce variability in the compiled data. The findings implied that curated polymer datasets and interpretable ML models can support the rational design of sustainable polymers with tailored properties for specific applications. Full article

(This article belongs to the Special Issue Computational Modeling of Polymer Composites and Nanocomposites)

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20 pages, 16363 KB

Open AccessArticle

Reinforcement and Toughening of Thermo-Compressed Guar Gum Films with Untreated Rice Husk for Eco-Friendly Packaging Applications

by Theeraphol Phromsopha and Yodthong Baimark

Polymers 2026, 18(13), 1558; https://doi.org/10.3390/polym18131558 (registering DOI) - 23 Jun 2026

Abstract

This study investigates the fabrication of eco-friendly composite films based on guar gum (GG) reinforced with untreated rice husk (URH) powder (5–30 wt%) via a thermocompression process. To the best of our knowledge, this is one of the first demonstrations of directly utilizing [...] Read more.

This study investigates the fabrication of eco-friendly composite films based on guar gum (GG) reinforced with untreated rice husk (URH) powder (5–30 wt%) via a thermocompression process. To the best of our knowledge, this is one of the first demonstrations of directly utilizing untreated rice husk as a multifunctional reinforcing filler in GG-based bioplastics without any chemical or surface modification, thereby eliminating energy-intensive pretreatment steps. Particle dispersion and interfacial adhesion were optimal up to 10 wt% loading, above which agglomeration occurred. The incorporation of URH enhanced the thermal stability of the matrix. Mechanical performance peaked at 10 wt% URH, exhibiting a 90% increase in tensile strength, a 32% increase in elongation at break, and a 246% improvement in toughness compared to the neat GG film. Furthermore, URH addition reduced moisture content and water vapor permeability while increasing the water contact angle. Although film opacity increased, the results demonstrate that URH acts as an effective multifunctional filler. These GG/URH composite films exhibit strong potential for scalable industrial applications in eco-friendly food packaging, including disposable pouches and trays, offering a sustainable alternative to petroleum-based plastic materials. Full article

(This article belongs to the Special Issue Polymer Packaging: Sustainable Innovations and Alternatives to Fossil-Based Materials)

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13 pages, 7111 KB

Open AccessArticle

Effect of Polymer Concentration and Surface Charge on Controllable Nanopesticides Delivery

by Ran Cao, Yue Wu, Nuo Xu, Yutao Zhang, Zhiqian Guo and Yisheng Xu

Polymers 2026, 18(13), 1557; https://doi.org/10.3390/polym18131557 (registering DOI) - 23 Jun 2026

Abstract

The efficacy of polymer-based nanopesticides (NPs) is strongly governed by carrier concentration and surface charge, which affect shell thickness, drug release kinetics, and photostability. However, the influence of these two factors in pesticide release and delivery performance remains unclear. This study introduces a [...] Read more.

The efficacy of polymer-based nanopesticides (NPs) is strongly governed by carrier concentration and surface charge, which affect shell thickness, drug release kinetics, and photostability. However, the influence of these two factors in pesticide release and delivery performance remains unclear. This study introduces a NIR-II fluorescence dye-tracing strategy to enable high-resolution monitoring of NP behavior in model plants. By systematically varying polymer concentration and copolymer blocks, we investigate their impact on release behavior, photostability, and stem uptake. As the polymer concentration increased, NPs demonstrated a controlled slow release and better photostability, yet a lower pesticide loading capability. In model plants, PISNPs transport quickly and can accumulate at wound sites, effectively offering antifungal properties. This work provides experimental evidence for optimizing polymer carrier design to achieve efficient, controlled release while minimizing photodegradation risks, offering practical guidelines for developing high-performance, low-risk nanopesticide formulations. Full article

(This article belongs to the Section Polymer Applications)

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24 pages, 3623 KB

Open AccessArticle

Intrinsic Chemical Consequences of Interface Failure in Composite Insulators Under Electrical Stress: PD-Induced Degradation of Epoxy/Anhydride Matrix and the Role of Humidity

by Kexin Shi, Dandan Zhang, Zhiyu Wan, Lixue Chen and Zhaohua Lu

Polymers 2026, 18(13), 1556; https://doi.org/10.3390/polym18131556 (registering DOI) - 23 Jun 2026

Abstract

This study investigates the decay-like degradation mechanisms of the matrix material in composite insulators, focusing on the pronounced influence of humid environments on partial discharge (PD) characteristics and degradation pathways. A sealed chamber discharge platform was established, integrating PD signal monitoring, surface characterization, [...] Read more.

This study investigates the decay-like degradation mechanisms of the matrix material in composite insulators, focusing on the pronounced influence of humid environments on partial discharge (PD) characteristics and degradation pathways. A sealed chamber discharge platform was established, integrating PD signal monitoring, surface characterization, and gas chromatography-mass spectrometry (GC-MS) with molecular network analysis to examine the synergistic effects of thermal influences from PD and active atmospheric particles at humidity levels of 0% RH, 50% RH, and 100% RH. Results show that dry conditions favor high-energy, low-repetition-rate discharges, promoting cleavage and recombination of high-bond-energy bonds (e.g., benzene rings and (α)C–O), yielding primarily long-chain carboxylic acids (C9 and above). In contrast, humid conditions shift to low-energy, high-repetition-rate discharges, with water vapor decomposition generating highly oxidizing hydroxyl radicals (·OH). These facilitate selective scission of lower-bond-energy (β)C–O bonds and deep oxidation, significantly increasing short-chain dicarboxylic acids—especially oxalic acid—whose acidity and water solubility are nearly an order of magnitude higher than in dry environments, becoming the dominant acidic products. The work demonstrates that many PD-generated organic acids act as intrinsic corrosive agents in insulating systems, independent of ambient nitric acid. This elucidates, at the reaction pathway level, how high humidity modulates PD to enhance corrosive acid production, providing a microchemical basis for understanding regional decay-like failure patterns in composite insulators. Full article

(This article belongs to the Special Issue Polymeric Composites for Electrical Insulation Applications)

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15 pages, 7015 KB

Open AccessArticle

Influence of Self-Adhesive Resin Composite Deep Marginal Elevation on the Sealing Ability of CAD/CAM Lithium Disilicate Glass-Ceramic Inlays: An In Vitro Study

by Rasha Haridy, Shadan Almotairi, Shoroug Alshehri, Abrar Nasser Bin Nooh and Moataz Elgezawi

Polymers 2026, 18(12), 1555; https://doi.org/10.3390/polym18121555 (registering DOI) - 22 Jun 2026

Abstract

Deep margin elevation (DME) is a conservative technique used to relocate subgingival proximal margins to a more favorable supragingival position, facilitating adhesive procedures and impression taking. This in vitro study evaluated the influence of two DME materials—a universal flowable resin composite and a [...] Read more.

Deep margin elevation (DME) is a conservative technique used to relocate subgingival proximal margins to a more favorable supragingival position, facilitating adhesive procedures and impression taking. This in vitro study evaluated the influence of two DME materials—a universal flowable resin composite and a self-adhesive flowable resin composite—on the cervical interfacial sealing ability of lithium disilicate glass–ceramic CAD/CAM inlay restorations. Twenty extracted maxillary premolars were randomly allocated into two groups (n = 10). Group A received DME using a universal flowable resin composite (3M™ Filtek™ Z350 XT) preceded by a conventional adhesive system, while Group B received DME using a self-adhesive flowable resin composite (Vertise™ Flow). All teeth were restored with lithium disilicate CAD/CAM inlays (CEREC Tessera) cemented with a self-adhesive resin cement (Breeze^®). Specimens underwent thermocycling (10,000 cycles; 5–55 °C). Marginal gaps were assessed at the DME interface using high-resolution micro-computed tomography (micro-CT) in both coronal and sagittal cross-sections, before and after thermocycling. Statistically significant differences were found between groups in both sections before and after thermocycling (p < 0.05). The self-adhesive composite (Group B) demonstrated significantly lower gap values compared to the universal flowable composite (Group A) in both coronal and sagittal assessments. Thermocycling increased the gap in both groups; however, Group B maintained considerably lower leakage. The self-adhesive resin composite showed superior sealing ability at the DME interface compared to the universal flowable composite when used under lithium disilicate glass–ceramic inlay restorations. Further clinical studies are recommended to validate these findings. Full article

(This article belongs to the Special Issue Bio-Based Polymeric Materials for Biomedical Applications)

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17 pages, 1271 KB

Open AccessArticle

Modulating Exciton Dynamics Through Fluorescent Side Group Incorporation in Benzodithiophene-Benzotriazole-Isoindigo Terpolymers

by René Hauyón, Yasmín Pérez, Daniela Zúñiga, Scarlet Araya, Bastian Camacho, Pablo Thomas, Cesar Saldías, Denis Fuentealba, Claudio A. Terraza, Felipe A. Angel and Ignacio A. Jessop

Polymers 2026, 18(12), 1554; https://doi.org/10.3390/polym18121554 (registering DOI) - 22 Jun 2026

Abstract

In this work, we investigated the incorporation of a fluorescent side group, fluorescein octyl ester (FOE), in benzodithiophene-based donor–acceptor terpolymers as a strategy to modulate excited-state behavior. Three FOE-containing terpolymers (P2-iIa-c), obtained at different polymerization times, were systematically evaluated against an [...] Read more.

In this work, we investigated the incorporation of a fluorescent side group, fluorescein octyl ester (FOE), in benzodithiophene-based donor–acceptor terpolymers as a strategy to modulate excited-state behavior. Three FOE-containing terpolymers (P2-iIa-c), obtained at different polymerization times, were systematically evaluated against an analogous material without the fluorescent pendant unit (P1-iI). Thermal analysis revealed good thermal stability and an increase in glass transition temperature upon FOE incorporation, suggesting restricted segmental mobility and increased conformational constraints within the conjugated backbone. Optical characterization showed distinct absorption spectra with reaction time and shorter fluorescence lifetimes for the FOE-containing materials, consistent with the presence of additional excited-state deactivation pathways and intramolecular energy transfer processes within the terpolymer backbone. An approximate estimation of energy transfer efficiencies (≈60–65%) suggested that such processes may be operative within the system. Cyclic voltammetry measurements showed only minor variations in HOMO and LUMO energy levels between P1-iI and P2-iIa-c series, indicating that the conjugated backbone predominantly determined the frontier orbital energies despite side chain modification. Furthermore, photocurrent measurements from the bilayer device configuration exhibited a systematic increase in photocurrent for the FOE-containing material, supporting the role of excitonic modulation, rather than significant changes in interfacial energetic alignment. These results suggest that fluorescent side chain incorporation provides an effective strategy for regulating exciton dynamics while maintaining the electronic structure of the donor–acceptor terpolymer. Full article

(This article belongs to the Section Polymer Chemistry)

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26 pages, 5414 KB

Open AccessArticle

PLA/PBSA Biocomposites Reinforced with Tangerine Tree-Derived Agro-Industrial Waste for Rigid Packaging: Effect of Extraction Treatment on Morphology and Thermo-Mechanical Performance

by Francesca Cartoni, Viola Berrugi, Aouatif Aboudia, Morad Chadni, Vito Gigante and Maria-Beatrice Coltelli

Polymers 2026, 18(12), 1553; https://doi.org/10.3390/polym18121553 (registering DOI) - 22 Jun 2026

Abstract

Bio-based and biodegradable polymer composites based on polylactic acid (PLA) and polybutylene succinate-co-adipate (PBSA) were developed for rigid food packaging applications. Agro-industrial residues consisting of ground leaves and branches derived from tangerine tree cultivation (pruning) were used as fillers at high loading (30 [...] Read more.

Bio-based and biodegradable polymer composites based on polylactic acid (PLA) and polybutylene succinate-co-adipate (PBSA) were developed for rigid food packaging applications. Agro-industrial residues consisting of ground leaves and branches derived from tangerine tree cultivation (pruning) were used as fillers at high loading (30 wt%) before (PRE) or after (POST) extraction of bioactive compounds. The influence of blend composition (PLA/PBSA 60/40 and 30/70), filler extraction, and the addition of antioxidants (0.5 wt%) on material properties was systematically investigated. Composites were processed via extrusion and injection molding and characterized through FTIR, SEM, tensile testing and thermal analysis. The results show that polymer blend morphology affects mechanical behavior, with co-continuous structures (60/40) exhibiting improved ductility compared to dispersed systems (30/70). The incorporation of lignocellulosic residues increased stiffness but reduced elongation at break. Extraction treatment significantly modified filler morphology and interfacial interactions, slightly improving dispersion and processability. The effect of the extracted bioactive compounds on the thermal stabilization of biocomposites was also investigated. Overall, the findings demonstrate the potential of combining biodegradable polymer blends with treated agricultural residues to produce sustainable rigid packaging materials while supporting a bio-circular approach. In fact, preliminary extraction of valuable compounds from tangerine pruning waste appears to be a convenient strategy for its efficient cascade valorization. Full article

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

23 pages, 1214 KB

Open AccessArticle

Synergistic Coatings Based on Chitosan and Eugenia caryophyllata Essential Oil to Improve Postharvest Quality of Capsicum chinense

by Fanor David Reyes Pérez, Yeimmy Peralta-Ruiz, Domingo César Carrascal-Hernández, Johannes Delgado-Ospina, Clemencia Chaves-López and Carlos David Grande-Tovar

Polymers 2026, 18(12), 1552; https://doi.org/10.3390/polym18121552 (registering DOI) - 22 Jun 2026

Abstract

The topito pepper (Capsicum chinense) is a tropical fruit of economic and gastronomic importance in the Caribbean region, valued for its nutritional content. However, this fruit is susceptible to postharvest fungal diseases, including those caused by the phytopathogenic fungus Penicillium expansum [...] Read more.

The topito pepper (Capsicum chinense) is a tropical fruit of economic and gastronomic importance in the Caribbean region, valued for its nutritional content. However, this fruit is susceptible to postharvest fungal diseases, including those caused by the phytopathogenic fungus Penicillium expansum, which can degrade fruit quality and pose a health risk due to the potential presence of mycotoxins such as patulin. In this context, we evaluated the protective effects of coatings with chitosan (CS), clove essential oil (CEO), and their combination (CS+CEO) on sweet peppers stored at 12 °C for 12 days after harvest. The results indicate that the film-forming solution exhibited an acidic pH (5.33–5.44), a density of ~1.0 g/cm³, and viscosities ranging from 2.75 to 32.9 cP. Furthermore, the results indicate that coatings with CS and CS+CEO significantly reduced weight loss, preserved firmness (19.12–30.40 N), and delayed ripening. At the same time, the coatings exhibited inhibitory effects on P. expansum and aerobic mesophiles. The CS+CEO combination demonstrated the greatest inhibitory effect, indicating that it is a sustainable and effective strategy for the postharvest preservation of sweet peppers, thereby enhancing their value, preservation, and food security in the Caribbean region. Full article

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

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17 pages, 1395 KB

Open AccessArticle

Bioethanol from Miscanthus × giganteus: A Comparative Study of Different Pretreatment Technologies

by Ekaterina A. Skiba, Ekaterina I. Kashcheyeva, Vladimir N. Zolotukhin, Galina F. Mironova and Vera V. Budaeva

Polymers 2026, 18(12), 1551; https://doi.org/10.3390/polym18121551 (registering DOI) - 22 Jun 2026

Abstract

Second-generation bioethanol technology is based on renewable raw materials with an unlimited potential for replenishment. However, the production cost of second-generation bioethanol is still higher than that of the first-generation. Biomass pretreatment is a key challenge, and solving it will improve the technology [...] Read more.

Second-generation bioethanol technology is based on renewable raw materials with an unlimited potential for replenishment. However, the production cost of second-generation bioethanol is still higher than that of the first-generation. Biomass pretreatment is a key challenge, and solving it will improve the technology efficiency. In this study, Miscanthus × giganteus from the Russian breeding stock was subjected to pretreatments with dilute HNO₃ under atmospheric pressure. Pretreatments were carried out either as a single stage (HNO₃) or as two stages ((i) HNO₃ followed by NaOH, and (ii) NaOH followed by HNO₃). Classical delignification with NaOH was also performed for comparison. Simultaneous saccharification and fermentation with delayed inoculation (dSSF) was then performed under identical conditions, with Saccharomyces cerevisiae Y-3136 as the microbial producer. Two-stage pretreatments were found to excel in purity, pulp composition, pulp conversion, bioethanol yield during fermentation, and raw bioethanol purity (impurities decreased by a factor of 21 compared to NaOH delignification). However, fermentation indicators are not the only critical aspect in bioethanol production technology. The complete cycle from Miscanthus × giganteus feedstock to the target bioethanol product was evaluated. The single-stage pretreatment with HNO₃ performed best among the tested conditions. The HNO₃ pretreatment achieved a 50% yield of pulps and a maximal bioethanol yield of 267 L/t, which is 44% higher compared to NaOH delignification. Furthermore, the HNO₃ pretreatment enables savings in resources and electric power, as well as full commercial utilization of all polymers of the lignocellulosic matrix of the feedstock. Full article

(This article belongs to the Special Issue Advances in Lignocellulose: Cellulose, Hemicellulose and Lignin)

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24 pages, 3593 KB

Open AccessArticle

Mulch Films Manufactured from Poly(Butylene Adipate-Co-Terephthalate) and Biopolymers Obtained from Urban and Agriculture Wastes: Mechanical Properties and Effects in Agriculture

by Enzo Montoneri, Philippe Evon, Jordane Charbonnier, Emanuele La Bella, Ferdinando Fragalà, Ivana Puglisi, Andrea Baglieri, Laurent Labonne, Landry Jégat, Solal Mendez, Simone Solaro, Elio Padoan and Jose L. Diéguez

Polymers 2026, 18(12), 1550; https://doi.org/10.3390/polym18121550 (registering DOI) - 22 Jun 2026

Abstract

Biopolymers (BPs), obtained from urban and agricultural wastes, are known as active principles to manufacture ready-for-use finished products in several sectors of the agriculture and chemical industries. These findings prospect a biowaste-based refinery producing chemical specialities to replace products derived from fossil feedstock. [...] Read more.

Biopolymers (BPs), obtained from urban and agricultural wastes, are known as active principles to manufacture ready-for-use finished products in several sectors of the agriculture and chemical industries. These findings prospect a biowaste-based refinery producing chemical specialities to replace products derived from fossil feedstock. The present paper reports new materials containing BPs. Composite granules containing Poly(Butylene Adipate-Co-Terephthalate (PBAT) as a matrix and BPs as fillers are manufactured by twin-screw extrusion. The granules are used to make single-layer PBAT-BP mulch films by single-screw extrusion and three-layer Starch-PBAT-BP films by blown co-extrusion. The films are tested for mechanical properties, and for structural stability and effects in the in vitro cress germination and the in-field horticulture. The results show that both the films’ effects on plant performance and the films’ structural degradation are regulated by the BP and polymeric matrix release kinetics in the operational germination medium or the field soil, and in turn, that the kinetics depend on the mulch film structural features. The horticulture trials prove that the three-layer mulch films have adequate mechanical strength (25 MPa maximum tensile strength and 520% elongation at break) and about 6 months lifespan to maintain and/or improve the soil protection and crop production (17 t/ha) over the plant seasonal cycle. These findings widen the range of renewable chemical specialities potentially producible by the envisioned biowaste-based refinery. Full article

(This article belongs to the Special Issue Process–Structure–Properties Relationships in Polymers and Polymer Composites)

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13 pages, 2047 KB

Open AccessArticle

Mechanical Properties of PUR and Latex Foams as Predictors for Seating or Lying Comfort

by Zoran Vlaović, Danijela Domljan, Tomislav Gržan and Goran Mihulja

Polymers 2026, 18(12), 1549; https://doi.org/10.3390/polym18121549 (registering DOI) - 22 Jun 2026

Abstract

Flexible polyurethane (PUR) foams and latex rubber foams are widely used in furniture and mattress cushioning, yet conventional standardized mechanical tests only partially capture comfort-relevant behavior, particularly in layered constructions where material interactions and sequencing can alter elastic response. This study aimed to [...] Read more.

Flexible polyurethane (PUR) foams and latex rubber foams are widely used in furniture and mattress cushioning, yet conventional standardized mechanical tests only partially capture comfort-relevant behavior, particularly in layered constructions where material interactions and sequencing can alter elastic response. This study aimed to compare the mechanical (elastic) properties of selected three-layer composites of approximately 60 mm thickness (composed of conventional PUR, high-resilience PUR, low-resilience PUR, and latex foam) and to preliminarily assess whether combining foam types improves support of such setup and whether changing layer order modifies elasticity and support. Indentation hardness testing of multilayer cushions was conducted by ISO 2439:2008 Method E. Six three-layer systems (Alpha–Zeta) were assembled in two groups. Group X showed nearly identical support factors (2.6–2.7), high recovery (64.3–66.2%), low hysteresis loss (24.3–24.5%), and overlapping force–indentation (IFD) curves, indicating minimal effect of layer order and dominance of the PUR layers. Group Y exhibited higher but more sequence-dependent support (3.1–3.7), markedly reduced, wider range recovery (30.0–45.9%), increased hysteresis (33.0–34.7%), and more dispersed IFD curves. Placing high-resilience foam at the top partially improve recovery, whereas locating low-resilience foam at the surface increase energy loss. The research contributes in part to the body of knowledge about the behavior of the tested materials according to standardized rules. These preliminary results can be compared with other research findings and used in the preparation of testing models for multilayer foam composites, thereby generating new knowledge to improve the design of future experiments, which will result in increased sitting and lying comfort. Full article

(This article belongs to the Special Issue Advanced Polymer Composites and Foams)

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24 pages, 22612 KB

Open AccessArticle

Effect of Beverages on the Surface Roughness and Staining of Modified Polyetheretherketone (PEEK) Materials

by Aybike Cengiz Dağtekin and Samet Tekin

Polymers 2026, 18(12), 1548; https://doi.org/10.3390/polym18121548 (registering DOI) - 22 Jun 2026

Abstract

This study investigates color and surface alterations in neat and modified PEEK materials (10 × 3 mm, n = 140) immersed in various beverage solutions. Surface roughness (Ra) and color change (ΔE) were analyzed, supported by SEM and AFM evaluations. Specimens polished with [...] Read more.

This study investigates color and surface alterations in neat and modified PEEK materials (10 × 3 mm, n = 140) immersed in various beverage solutions. Surface roughness (Ra) and color change (ΔE) were analyzed, supported by SEM and AFM evaluations. Specimens polished with 400–1200 grit sandpaper were measured via profilometry before a 30-day immersion in distilled water, coffee, tea, cola, and red wine (refreshed every 12 h). Post-immersion results indicated that material and solution types significantly influenced Ra and ΔE values (p < 0.05), with the TP group being the least affected. Statistically, tea caused the greatest discoloration. The GFP group exhibited the highest Ra, indicating inferior surface stability, whereas TP and CR groups remained below the 0.2 μm clinical threshold. Specifically, the TP group demonstrated the lowest Ra value. Although perceptible color changes occurred in all materials, a positive correlation was identified between material type and beverage solutions. SEM and AFM analyses confirmed the presence of surface micro-cracks and morphological irregularities. Full article

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

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