Polymers

13 pages, 2363 KB

Open AccessArticle

Preparation and Paclitaxel-Loading of Regenerated Chitin Nanoparticles

by Yanping Li, Dan Qiu, Xuechen Zhuang, Zhiduo Pei, Tao Li and Shanggui Deng

Polymers 2025, 17(22), 3036; https://doi.org/10.3390/polym17223036 (registering DOI) - 16 Nov 2025

This study aims to investigate biodegradable and biocompatible chitin as a natural carrier for loading the hydrophobic anti-cancer drug paclitaxel (PTX) for the first time, resulting in a new loading system of chitin nanoparticles–paclitaxel (ChNps–PTX). The well-dispersed chitin nanoparticles (ChNps) and ChNps–PTX were [...] Read more.

This study aims to investigate biodegradable and biocompatible chitin as a natural carrier for loading the hydrophobic anti-cancer drug paclitaxel (PTX) for the first time, resulting in a new loading system of chitin nanoparticles–paclitaxel (ChNps–PTX). The well-dispersed chitin nanoparticles (ChNps) and ChNps–PTX were prepared via a water-dripping regeneration method. The functional groups, crystal form, and the high degree of acetylation (DA = 96.03%) of ChNps did not change during regeneration, suggesting that ChNps retained the complete molecular structure of chitin. The average particle size of ChNps–PTX was approximately 93.11 nm, which was larger than that of ChNps (84.06 nm) because of loading PTX (the drug loading was approximately 8.01%). TEM and CLSM were employed to confirm PTX existence in ChNps–PTX, and the nano-strip PTX (30.52 ± 6.78 nm in length and 16.02 ± 2.77 nm in width) was found for the first time. Loading of PTX resulted in ChNps–PTX presenting a new characteristic peak at 1734 cm⁻¹ in FT-IR spectra, a new peak at 2θ = 5.3° in XRD pattern, and a new exothermic peak (252 °C) in DSC curve. While ChNps–PTX showed a lower crystallinity (19.86%) compared with that of ChNps (24.11%) and chitin (36.77%), utilizing the chitin carrier and mild regeneration method to load PTX were highly beneficial for pharmaceutical fields. Full article

(This article belongs to the Special Issue Additive Manufactuging of Polymer-Based Nanocomposites and Composites: Progress and Prospects)

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25 pages, 4102 KB

Open AccessArticle

Reusable 3D-Printed Thermoplastic Polyurethane Honeycombs for Mechanical Energy Absorption

by Alin Bustihan, Razvan Hirian and Ioan Botiz

Polymers 2025, 17(22), 3035; https://doi.org/10.3390/polym17223035 (registering DOI) - 16 Nov 2025

Abstract

In this study, we investigate the mechanical energy absorption performance of reusable 3D-printed honeycomb structures fabricated using fused deposition modeling with three thermoplastic polyurethane variants: TPU 70A, TPU 85A, and TPU 95A. Prior to manufacturing, the mechanical properties of the TPU filaments were [...] Read more.

In this study, we investigate the mechanical energy absorption performance of reusable 3D-printed honeycomb structures fabricated using fused deposition modeling with three thermoplastic polyurethane variants: TPU 70A, TPU 85A, and TPU 95A. Prior to manufacturing, the mechanical properties of the TPU filaments were analyzed as a function of printing temperature to optimize tensile strength and layer adhesion. Four honeycomb configurations, including hexagonal and circular cell geometries, both with and without a 30° twist, were subjected to out-of-plane compression testing to evaluate energy absorption efficiency, specific energy absorption, and crushing load efficiency. The highest energy absorption efficiency, 47%, was achieved by the hexagonal honeycomb structure fabricated from TPU 95A, surpassing the expected values for expanded polystyrene and approaching the performance reported for high-cost advanced lattice structures. Additionally, twisted honeycomb configurations exhibited improved crushing load efficiency values (up to 73.5%), indicating better stress distribution and enhanced reusability. Despite variations in absorbed energy, TPU 95A demonstrated the best balance of elasticity, structural integrity, and reusability across multiple compression cycles. These findings suggest that TPU-based honeycomb structures could provide a viable, cost-effective alternative for energy-absorbing applications in impact protection systems, automotive safety, and sports equipment. Full article

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

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13 pages, 5530 KB

Open AccessArticle

Investigation of Metallo(organo)siloxane—Polydimethylsiloxane Composites with a High Metallosiloxane Component Content

by Nadezhda A. Tebeneva, Alexander N. Tarasenkov, Ivan B. Meshkov, Aleksandra A. Kalinina, Alexander I. Buzin, Mikhail I. Buzin, Galina P. Goncharuk and Aziz M. Muzafarov

Polymers 2025, 17(22), 3034; https://doi.org/10.3390/polym17223034 (registering DOI) - 16 Nov 2025

Abstract

A representative series of functional branched metallosiloxane oligomers was used to obtain polydimethylsiloxane-based composites highly filled with a metallosiloxane component. Physical and mechanical characteristics of compositions obtained strongly depends on metallosiloxane structure and composition. It is shown that it is possible to regulate [...] Read more.

A representative series of functional branched metallosiloxane oligomers was used to obtain polydimethylsiloxane-based composites highly filled with a metallosiloxane component. Physical and mechanical characteristics of compositions obtained strongly depends on metallosiloxane structure and composition. It is shown that it is possible to regulate the strength and elastic properties of the systems under consideration within wide limits, as well as to influence the morphology of the material. The resulting materials are rather thermo-oxidatively stable and can also maintain high mobility of polydimethylsiloxane chains. Full article

(This article belongs to the Special Issue Polymeric Composites: Manufacturing, Processing and Applications)

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16 pages, 2447 KB

Open AccessArticle

Assessment of the Stability of Propellants Modified with Eco-Friendly Plasticizers

by Katarzyna Cieślak, Monika Izabella Wycech and Waldemar Tomaszewski

Polymers 2025, 17(22), 3033; https://doi.org/10.3390/polym17223033 (registering DOI) - 15 Nov 2025

Abstract

The growing importance of sustainable technologies and environmental safety is promoting the implementation of green chemistry principles in the field of energetic materials. Traditionally, nitrocellulose-based propellants are plasticized with dibutyl phthalate (DBP), which is classified as a hazardous substance due to its toxicity [...] Read more.

The growing importance of sustainable technologies and environmental safety is promoting the implementation of green chemistry principles in the field of energetic materials. Traditionally, nitrocellulose-based propellants are plasticized with dibutyl phthalate (DBP), which is classified as a hazardous substance due to its toxicity and migration during storage. In this work, triethyl 2-acetylcitrate (ATEC) and tributyl 2-acetylcitrate (ATBC) were investigated as biodegradable and non-toxic alternatives to DBP. The objective of this study was to evaluate the thermal and chemical stability, physicochemical properties, and incorporation efficiency of these eco-friendly plasticizers in regard to propellants prepared from nitrocellulose of different origins and with nitrogen contents. The stability of the obtained propellants was assessed based on accelerated aging tests conducted in accordance with NATO STANAG 4582 and AOP-48 procedures. The results showed that both the ATEC- and ATBC-modified propellants meet the stability requirements corresponding to at least ten years of storage at 25 °C. The modified propellants showed slightly lower heats of combustion. Both plasticizers were effectively integrated into the nitrocellulose matrix without compromising density or stability. This study confirms that citric-acid-based plasticizers are promising green alternatives to conventional phthalates, offering improved environmental compatibility while maintaining the required performance and safety of nitrocellulose propellants. Full article

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

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12 pages, 1282 KB

Open AccessArticle

Disposable Foamed Silicone Composite Actuator Powered by Sublimation

by Igor Bezsudnov, Alina Khmelnitskaia, Aleksandra Kalinina and Sergey Ponomarenko

Polymers 2025, 17(22), 3032; https://doi.org/10.3390/polym17223032 (registering DOI) - 15 Nov 2025

Abstract

Soft actuators are widely explored as movers in various devices, human–machine interfaces, for medical purposes and other biomedical applications. Among them are soft actuators based on a foamed silicone matrix with the working liquid (WL) captured in its pores that undergo the liquid–gas [...] Read more.

Soft actuators are widely explored as movers in various devices, human–machine interfaces, for medical purposes and other biomedical applications. Among them are soft actuators based on a foamed silicone matrix with the working liquid (WL) captured in its pores that undergo the liquid–gas phase transition. For the first time, to gain the actuation strain of such composites, we added, to the WL, a substance that sublimates during the composite actuation. C1–C3 alcohols were tested as WLs, while the sublimation substance (SS) used was benzoic acid dissolved in the WL. It was found that the rejuvenation procedure is able to fill the composite pores with WL + SS solution. The effect of benzoic acid addition was revealed using the two-stage heating mode. The sublimation substance effectively extends the composite strain for methanol and ethanol as WL for about 20%. For C3 propanols, the strain is left nearly unchanged. In the open-air conditions, the high diffusion of WL + SS in silicone allows only a single actuation that makes it a disposable actuator, i.e., a kind of safety switch is proposed. The results obtained in this work pave the way to future, powerful multipurpose “soft safeties” appliances. Full article

(This article belongs to the Special Issue Polymeric Composites: Manufacturing, Processing and Applications)

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24 pages, 5078 KB

Open AccessArticle

Numerical Study on Elastic Properties of Natural Fibres in Multi-Hybrid Composites

by Mughees Shahid, Gediminas Monastyreckis and Daiva Zeleniakiene

Polymers 2025, 17(22), 3031; https://doi.org/10.3390/polym17223031 (registering DOI) - 15 Nov 2025

Abstract

This study investigates the elastic properties of bio-epoxy composites reinforced with natural fibres (flax, hemp) and synthetic fibres (S-glass), with particular focus on the effect of the fibre volume fraction (VF) ranging from 10% to 70%. Three-dimensional representative volume element (RVE) models were [...] Read more.

This study investigates the elastic properties of bio-epoxy composites reinforced with natural fibres (flax, hemp) and synthetic fibres (S-glass), with particular focus on the effect of the fibre volume fraction (VF) ranging from 10% to 70%. Three-dimensional representative volume element (RVE) models were developed for single-fibre, hybrid, and multi-fibre systems. The mean-field homogenisation (MF) approach, based on the Mori–Tanaka scheme, and finite element analysis (FEA) with periodic boundary conditions were employed to predict the effective elastic properties, including longitudinal, transverse, and shear moduli, as well as Poisson’s ratio. These numerical predictions were validated against analytical models, including the rule of mixtures, Chamis, and composite cylinder assemblage (CCA) methods. The results demonstrate that increasing the VF enhances longitudinal, transverse, and shear moduli while reducing Poisson’s ratio in natural fibre composites. The good agreement between numerical, semi-analytical, and analytical methods validates the 3D RVE models as useful tools for predicting the properties of multi-hybrid natural fibre composites, supporting their design for lightweight structural applications. Full article

(This article belongs to the Special Issue Theoretical and Computational Polymers Science: Physics, Chemistry and Biology—2nd Edition)

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21 pages, 2732 KB

Open AccessArticle

Ionic Conductive Hydrogels with Choline Salt for Potential Use in Electrochemical Capacitors

by Jan Malczak, Wiktoria Żyła, Piotr Gajewski, Katarzyna Szcześniak, Łukasz Popenda and Agnieszka Marcinkowska

Polymers 2025, 17(22), 3030; https://doi.org/10.3390/polym17223030 - 14 Nov 2025

Abstract

Choline salts represent sustainable and safe electrolyte systems. In this study, an aqueous 1 M choline nitrate solution was employed to prepare hydrogel polymer electrolytes (HPE) via in situ photopolymerization. To enhance compatibility between the electrolyte and polymer matrix, choline methacrylate was synthesized [...] Read more.

Choline salts represent sustainable and safe electrolyte systems. In this study, an aqueous 1 M choline nitrate solution was employed to prepare hydrogel polymer electrolytes (HPE) via in situ photopolymerization. To enhance compatibility between the electrolyte and polymer matrix, choline methacrylate was synthesized and used as a functional monomer alongside HEMA and PEGDA. The photocurable formulation contained 70 wt.% electrolyte and 30 wt.% monomer mixture. Subsequent electrolyte uptake increased the electrolyte fraction in the HPE to 87 wt.%. The use of choline methacrylate enabled the formation of transparent HPE with favorable mechanical performance, showing puncture resistance of 0.33 N and 0.28 N at elongations of 7.9 mm and 4.4 mm for samples with 70 and 87 wt.% electrolyte, respectively. High ionic conductivity was achieved, reaching ~18 mS/cm and ~34 mS/cm for HPE with 70 and 87 wt.% electrolyte. Finally, a capacitor assembled with HPE containing 87 wt.% electrolyte demonstrated good operational parameters, confirming the applicability of this system in energy storage devices. This work highlights the potential of choline-based electrolytes and polymerizable choline derivatives as functional components for the design of efficient, safe, and environmentally friendly gel polymer electrolytes. Full article

(This article belongs to the Special Issue Active Polymeric Materials for Electrochemical Applications)

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20 pages, 1313 KB

Open AccessArticle

Drop Hammer Impact Ignition Experiment and Effect of Additives on Energy Release Characteristics of PTFE-Based Reactive Materials

by Junming Yuan, Jiaying Gu, Zhe Zhai, Jinying Wang, Peijiang Han, Jiangqi Linghu and Yang Liu

Polymers 2025, 17(22), 3029; https://doi.org/10.3390/polym17223029 - 14 Nov 2025

Abstract

To solve the problem of low energy release efficiency of fluoropolymer-based reactive materials, four PTFE (Polytetrafluoroethylene) -based reactive structural materials with different contents were prepared by adding traditional energetic materials (RDX, 1,3,5-Trinitrohexahydro-1,3,5-triazine) and alloy metals (aluminum magnesium, aluminum magnesium zinc). In addition, in [...] Read more.

To solve the problem of low energy release efficiency of fluoropolymer-based reactive materials, four PTFE (Polytetrafluoroethylene) -based reactive structural materials with different contents were prepared by adding traditional energetic materials (RDX, 1,3,5-Trinitrohexahydro-1,3,5-triazine) and alloy metals (aluminum magnesium, aluminum magnesium zinc). In addition, in order to reduce the high cost of the existing high-speed impact energy release testing device, the formulation optimization of PTFE-based aluminum alloy reactive material was efficiently carried out using a small-scale drop hammer impact test in this paper. The self-designed impact energy release testing device was established for the overpressure measurement of PTFE-based aluminum alloy reactive materials. The impact response processes of PTFE-based aluminum alloy reactive material were recorded with high-speed photography. The energy release characteristics were quantified using overpressure measurements. Based on the chemical reaction properties and microstructural characterization of the PTFE-based reactive materials, the ignition mechanism of aluminum alloy reactive materials was analyzed under drop hammer impact load. The results show that the quantitative characterization of the overpressure changes of reactive materials in a quasi-enclosed space before and after reaction can reflect their energy release efficiency under low-velocity impact by using the drop hammer impact energy release testing device. The order of impact response overpressure values for four PTFE-based reactive materials has been conducted. The aluminum alloy reactive material containing RDX explosive has the highest overpressure value and the highest energy release efficiency in terms of drop hammer impact response. Based on the ignition mechanism and energy release characteristics of these four PTFE-based reactive materials, it was found that the addition of alloy metal powder can reduce impact sensitivity, but when activated, it can effectively enhance the damage effect. Full article

(This article belongs to the Special Issue High-Energy-Density Polymer-Based Materials)

5 pages, 168 KB

Open AccessEditorial

Polysaccharide-Based Materials: Developments and Properties

by Andrés Gerardo Salvay

Polymers 2025, 17(22), 3028; https://doi.org/10.3390/polym17223028 - 14 Nov 2025

Abstract

The growing concern for environmental sustainability and the urgent demand to reduce dependence on non-renewable resources have placed bio-based materials at the centre of materials science innovation [...] Full article

(This article belongs to the Special Issue Polysaccharide-Based Materials: Developments and Properties)

21 pages, 1295 KB

Open AccessArticle

Incorporation of Natural Biostimulants in Biodegradable Mulch Films for Agricultural Applications: Ecotoxicological Evaluation

by Chelo Escrig Rondán, Celia Sevilla Gil, Pablo Sanz Fernández, Juan Francisco Ferrer Crespo and Cristina Furió Sanz

Polymers 2025, 17(22), 3027; https://doi.org/10.3390/polym17223027 - 14 Nov 2025

Abstract

This study deals with the incorporation of biostimulants of natural origin in a biodegradable polymeric matrix, with the aim of developing mulch films that, when degraded in the soil, release bioactive compounds that improve soil quality and favor the agronomic growth of crops. [...] Read more.

This study deals with the incorporation of biostimulants of natural origin in a biodegradable polymeric matrix, with the aim of developing mulch films that, when degraded in the soil, release bioactive compounds that improve soil quality and favor the agronomic growth of crops. Three types of commercial biostimulants were used: one based on seaweed extract, one on lignosulfonates, and one on plant-derived essential amino acids. To ensure the thermal stability of the biostimulant compounds during processing, thermogravimetric analyses (TGAs) were carried out, and a methodology based on the adsorption of the biostimulants onto porous substrates was developed, enabling their effective incorporation into the polymeric matrix. The formulations obtained have been processed by blown film extrusion at a pilot scale. In addition, the presence of film residues in soil was analyzed by pyrolysis–gas chromatography–mass spectrometry (Py-GC/MS). The results indicate that the proposed methodology supports the integrity of the biostimulants in the films obtained. After the incubation period studied, complete degradation of the biopolymer and the absence of film residues in the soil were confirmed. Furthermore, it was confirmed that this final product had no adverse effects on organisms that were representative of the two end-of-life scenarios, with the exception of the film functionalized with the commercial biostimulant based on seaweed extract, which showed a negative effect on terrestrial higher plants. Full article

(This article belongs to the Special Issue New Progress in Biodegradable Polymeric Materials)

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14 pages, 2588 KB

Open AccessArticle

Effect of Drying Methods on the Morphological and Functional Properties of Cellulose Ester Films

by Tanuj Kattamanchi, Heikko Kallakas, Elvira Tarasova, Percy Festus Alao, Tiit Kaljuvee, Arvo Mere, Atanas Katerski, Rünno Lõhmus, Andres Krumme and Jaan Kers

Polymers 2025, 17(22), 3026; https://doi.org/10.3390/polym17223026 - 14 Nov 2025

Abstract

This study presents the synthesis and characterisation of cellulose long chain fatty acid ester films using a novel distillable ionic liquid (IL), 5-methyl-1,5,7-triaza-bicyclo-[4.3.0] non-6-enium acetate [mTBNH][OAc] in combination with DMSO as a cosolvent. The cellulose esters cellulose diacetate (CDA), cellulose laurate (CL), and [...] Read more.

This study presents the synthesis and characterisation of cellulose long chain fatty acid ester films using a novel distillable ionic liquid (IL), 5-methyl-1,5,7-triaza-bicyclo-[4.3.0] non-6-enium acetate [mTBNH][OAc] in combination with DMSO as a cosolvent. The cellulose esters cellulose diacetate (CDA), cellulose laurate (CL), and cellulose palmitate (CP) were fabricated through an evaporation-induced phase separation method (EIPS) and dried under two conditions: conventional oven drying (RO) and vacuum oven drying (VO). The influence of drying conditions on the structural, thermal, and surface properties of the films was evaluated using XRD, TGA, SEM, AFM, and contact angle measurement techniques. XRD confirmed an amorphous structure in all films, with no significant effect on the drying conditions. TGA revealed consistent thermal degradation profiles across all samples, with ester group decomposition accruing between 140 and 250 °C and main cellulose backbone degradation near 350 °C. The SEM cross-section showed a uniform film, devoid of cavities and layered structures. AFM analysis demonstrated that VO-dried films had smoother surfaces compared to RO-dried films, correlating with increased contact angles and enhanced hydrophobicity. A strong inverse relationship between surface roughness and hydrophobicity was observed, particularly in VO-dried samples, although this was not statistically significant due to data variability. Overall, the drying method had minimal impact on the internal structure and thermal stability; it significantly influenced surface morphology and wettability. Full article

(This article belongs to the Special Issue Advances in the Preparation, Properties and Application of Polyurethane, Cellulose and Their Composites (3rd Edition))

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17 pages, 2415 KB

Open AccessArticle

Dynamic Monitoring Method of Polymer Injection Molding Product Quality Based on Operating Condition Drift Detection and Incremental Learning

by Guancheng Shen, Sihong Li, Yun Zhang, Huamin Zhou and Maoyuan Li

Polymers 2025, 17(22), 3025; https://doi.org/10.3390/polym17223025 - 14 Nov 2025

Abstract

Prediction models for polymer injection molding quality often degrade due to shifts in operating conditions caused by variations in melting temperature, cooling efficiency, or machine conditions. To address this challenge, this study proposes a drift-aware dynamic quality-monitoring framework that integrates hybrid-feature autoencoder (HFAE) [...] Read more.

Prediction models for polymer injection molding quality often degrade due to shifts in operating conditions caused by variations in melting temperature, cooling efficiency, or machine conditions. To address this challenge, this study proposes a drift-aware dynamic quality-monitoring framework that integrates hybrid-feature autoencoder (HFAE) drift detection, sliding-window reconstruction error analysis, and a mixed-feature artificial neural network (ANN) for online quality prediction. First, shifts in processing parameters are rigorously quantified to uncover continuous drifts in both input and conditional output distributions. A HFAE monitors reconstruction errors within a sliding window to promptly detect anomalous deviations. Once the drift index exceeds a predefined threshold, the system automatically triggers a drift-event response, including the collection and labeling of a small batch of new samples. In benchmark tests, this adaptive scheme outperforms static models, achieving a 35.4% increase in overall accuracy. After two incremental updates, the root-mean-squared error decreases by 42.3% across different production intervals. The anomaly detection rate falls from 0.86 to 0.09, effectively narrowing the distribution gap between training and testing sets. By tightly coupling drift detection with online model adaptation, the proposed method not only maintains high-fidelity quality predictions under dynamically evolving injection molding conditions but also demonstrates practical relevance for large-scale industrial production, enabling reduced rework, improved process stability, and lower sampling frequency. Full article

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

24 pages, 8615 KB

Open AccessArticle

Xylitol Modification of Electrospun Polymer Scaffolds: Impact on Physicochemical and Antibacterial Properties

by Francesco Boschetto, Matteo Zanocco, Kaeko Kamei, Huaizhong Xu and Elia Marin

Polymers 2025, 17(22), 3024; https://doi.org/10.3390/polym17223024 - 14 Nov 2025

Abstract

Electrospun fibrous scaffolds based on cellulose acetate (CA), polycaprolactone (PCL), and poly (L-lactic acid) (PLLA) are versatile materials with applications spanning diverse fields, but in their pristine form, they typically lack significant inherent antibacterial properties. To address this limitation and expand their utility, [...] Read more.

Electrospun fibrous scaffolds based on cellulose acetate (CA), polycaprolactone (PCL), and poly (L-lactic acid) (PLLA) are versatile materials with applications spanning diverse fields, but in their pristine form, they typically lack significant inherent antibacterial properties. To address this limitation and expand their utility, this study explored the incorporation of xylitol, a natural antibacterial sugar alcohol, into these polymer matrices to enhance their physicochemical and antimicrobial properties. Electrospinning was employed to fabricate pristine and xylitol-loaded scaffolds with varying xylitol concentrations. Morphological analysis revealed polymer-dependent changes in fiber diameter and porosity. Mechanical testing assessed the impact of xylitol on tensile properties, while thermal analysis investigated alterations in melting temperature and crystallinity. The antibacterial efficacy against Staphylococcus aureus and Escherichia coli was evaluated using WST assay and live/dead staining. Notably, xylitol significantly enhanced the antibacterial activity against both bacterial species, with a more pronounced and rapid effect observed against S. aureus. The tailored scaffold properties and imparted antimicrobial characteristics highlight the potential of these xylitol-modified electrospun materials: they are easily produced, low-cost, and appropriate for a range of applications (dental applications, filters, masks, wound dressing, and packaging) where preventing bacterial contamination is crucial. Full article

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

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15 pages, 1467 KB

Open AccessArticle

Wood Bio-Adhesives Made by Polymerizing Oxidized Starch with Deep Eutectic Solvent-Modified Lignin

by Hamed Younesi-Kordkheili and Antonio Pizzi

Polymers 2025, 17(22), 3023; https://doi.org/10.3390/polym17223023 - 14 Nov 2025

Abstract

In the present work, a new bio-sourced adhesive system based on deep eutectic solvent-modified lignin and oxidized starch (OSTL) resin is presented. For this purpose, unmodified and choline chloride–Zinc chloride (ChCl–ZnCl₂) deep eutectic solvent modified lignin at different contents (10%, 20%, [...] Read more.

In the present work, a new bio-sourced adhesive system based on deep eutectic solvent-modified lignin and oxidized starch (OSTL) resin is presented. For this purpose, unmodified and choline chloride–Zinc chloride (ChCl–ZnCl₂) deep eutectic solvent modified lignin at different contents (10%, 20%, and 30%) were used to prepare the OSTL resin. Ammonium persulfate (APS) was the oxidizer employed for the oxidation of starch, and urea was used as a low cost and effective crosslinker agent in the OSTL resin. FTIR analysis indicated that the content of carboxyl and carbonyl groups changed after the curing of the OSTL resin compared to oxidized starch (OST). DSC analysis indicated that the curing temperature of the OSTL resin containing DES-modified lignin was lower than that for unmodified lignin. Also, greater dimensional stability and mechanical strength could be achieved by increasing the amount of DES-treated lignin in the OSTL wood adhesive from 10 to 30 wt%. Based on the findings of this research, the physical and mechanical properties of the particleboard panels bonded with this type of bio-adhesive were acceptable according to the relevant standards. Additionally, urea can thus be used as a good cross-linker, not only to crosslink just OST, but also to connect DES-modified lignin and oxidized starch molecules. Under the conditions used, particleboards bonded with an oxidized starch–urea–pristine lignin adhesive presented decreasing internal bond (IB) strength with an increasing proportion of lignin. Conversely, when the same adhesive using DES-modified lignin was used, the internal bond (IB) strength improved with the increasing proportion of DES-modified lignin. At 30% proportions of lignin, the oxidized starch–urea–DES-modified lignin presented a 27% improvement in strength. Finally, it can be noted that this work brings a new insight to the development and application of lignin-based bio-adhesives to bond wood-based panels. Full article

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

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20 pages, 4913 KB

Open AccessArticle

Biorenewable FDCA-Based Alkyd Resins for More Sustainable Wood Coatings

by Victor Klushin, Ivan Zubkov, Dmitry Petrenko, Alina Petrenko, Tatyana Yurieva, Tatyana Belichenko, Aleksey Yatsenko, Yash Kataria and Anna Ulyankina

Polymers 2025, 17(22), 3022; https://doi.org/10.3390/polym17223022 - 14 Nov 2025

Abstract

Alkyd resins (ARs) represent a significant development in synthetic polymers, being among the oldest ones and playing a crucial role in numerous applications, especially within the coating sector. The trend is moving towards replacing non-renewable resources in the production of ARs with bio-based [...] Read more.

Alkyd resins (ARs) represent a significant development in synthetic polymers, being among the oldest ones and playing a crucial role in numerous applications, especially within the coating sector. The trend is moving towards replacing non-renewable resources in the production of ARs with bio-based alternatives, with the goal of creating more sustainable binder materials as part of the transition to a bioeconomy. 2,5-Furandicarboxylic acid (FDCA) serves as a promising biomass-derived “building block” to replace non-renewable petroleum-derived aromatic diacids and anhydrides in AR synthesis. Various vegetable oils, including sunflower seed (SFO) and linseed oils (LSO), were utilized along with pentaerythritol (P) and glycerol (G) as polyols. FTIR and ¹H NMR spectroscopies were conducted for the verification of alkyd structures. The synthesized ARs were assessed for their physico-chemical properties, including acid value, hydroxyl value, color, density, and viscosity. The performance of the resulting alkyd coatings, which are crucial for their commercial applications, was examined. Key factors such as drying time, hardness, adhesion, wettability, chemical and corrosion resistance, and UV stability were analyzed. All synthesized FDCA-based alkyd coatings demonstrate outstanding adhesion, good thermal stability up to 220 °C, and barrier properties for steel with |Z|_0.02Hz ~10⁶–10⁷ Ohm cm⁻², which render them suitable for the processing requirements of indoor coating applications. The higher temperature at 50% mass loss (T₅₀) for SFO-P (397 °C) and LSO-P (413 °C) as compared to SFO-G (380 °C) and LSO-G (394 °C) indicated greater resistance to thermal breakdown when pentaerythritol was used as a polyol. Replacing glycerol with pentaerythritol in FDCA-based ARs resulted in a viscosity increase of 1.2–2.4 times and an enhancement in hardness from 2H to 3H. FDCA-based ARs exhibited decreased tack-free time, enhanced thermomechanical properties, and similar hardness as compared to phthalic anhydride-based ARs, underscoring the potential of FDCA as a sustainable alternative to phthalic anhydride in the formulation of ARs, integrating a greater proportion of renewable components for wood coating applications. Full article

(This article belongs to the Special Issue Eco-Friendly Polymeric Coatings and Adhesive Technology, 2nd Edition)

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15 pages, 2609 KB

Open AccessArticle

Research on Diagnostic Methods for Gas Generation Due to Degradation of Cable PVC Materials Under Electrical and Thermal Stress

by Peng Zhang, Xingwang Huang, Jingang Su, Zhen Liu, Xianhai Pang, Zihao Wang and Yidong Chen

Polymers 2025, 17(22), 3021; https://doi.org/10.3390/polym17223021 - 13 Nov 2025

Abstract

Polyvinyl chloride (PVC), owing to its excellent electrical properties and low cost, is widely applied in the inner insulation and outer sheath of cables. To achieve early fault warning based on characteristic gases, this study integrates experimental testing with molecular simulations to systematically [...] Read more.

Polyvinyl chloride (PVC), owing to its excellent electrical properties and low cost, is widely applied in the inner insulation and outer sheath of cables. To achieve early fault warning based on characteristic gases, this study integrates experimental testing with molecular simulations to systematically reveal the decomposition and gas generation characteristics of different PVC layers under electrical and thermal stresses. The results indicate that inner-layer PVC under electrical stress predominantly generates small-molecule olefins and halogenated hydrocarbons, while outer-layer PVC during thermal decomposition mainly produces hydrogen chloride, alkanes, and fragments of plasticizers. The surrounding atmosphere significantly regulates the gas generation pathways: air promotes the formation of CO₂ and H₂O, whereas electrical discharges accelerate the release of unsaturated hydrocarbons such as acetylene. By employing TG-FTIR, ReaxFF molecular dynamics, and DFT spectral calculations, a normalized infrared spectral library covering typical products was established and combined with the non-negative least squares method to realize quantitative deconvolution of mixed gases. Ultimately, a diagnostic system was constructed based on the concentration ratios of characteristic gases, which can effectively distinguish the failure modes of inner and outer PVC layers as well as different stress types. This provides a feasible approach for early detection of cable faults and supports intelligent maintenance strategies. Full article

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

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29 pages, 6467 KB

Open AccessArticle

Shear Performance and Numerical Simulation of Adhesively Bonded Joints in Multi-Jet Fusion 3D-Printed Polyamide Components

by Frantisek Sedlacek, Martin Stejskal, Nikola Bednarova and Ondrej Spacek

Polymers 2025, 17(22), 3020; https://doi.org/10.3390/polym17223020 - 13 Nov 2025

Abstract

Additive manufacturing technologies are no longer limited to rapid prototyping but are increasingly used for low-volume production of functional end-use components. Among advanced AM techniques, HP Multi-Jet Fusion (MJF) stands out for its high precision and efficiency. Polyamides, thanks to their balanced mechanical [...] Read more.

Additive manufacturing technologies are no longer limited to rapid prototyping but are increasingly used for low-volume production of functional end-use components. Among advanced AM techniques, HP Multi-Jet Fusion (MJF) stands out for its high precision and efficiency. Polyamides, thanks to their balanced mechanical and thermal properties, are commonly used as building materials in this technology. However, these materials are notoriously difficult to bond with conventional adhesives. This study investigates the shear strength of bonded joints made from two frequently used MJF materials—PA12 and glass-bead-filled PA12—using four different industrial adhesives. Experimental procedures were conducted according to ASTM standards. Specimens for single-lap-shear tests were fabricated on an HP MJF 4200 series printer, bonded using a custom jig, and tested on a Zwick-Roell Z250 electro-mechanical testing machine. Surface roughness of the adherends was measured with a 3D optical microscope to assess its influence on bonding performance. The polyurethane-based adhesive (3M Scotch-Weld DP620NS) demonstrated superior performance with maximum shear strengths of 5.0 ± 0.35 MPa for PA12 and 4.4 ± 0.03 MPa for PA12GB, representing 30% and 17% higher strength, respectively, compared to epoxy-based alternatives. The hybrid cyanoacrylate–epoxy adhesive (Loctite HY4090) was the only system showing improved performance with glass-bead-reinforced substrate (16.5% increase from PA12 to PA12GB). Statistical analysis confirmed significant differences between adhesive types (F_3,24 = 31.37, p < 0.001), with adhesive selection accounting for 65.7% of total performance variance. In addition to the experimental work, a finite element-based numerical simulation was performed to analyze the distribution of shear and peel stresses across the adhesive layer using Siemens Simcenter 3D 2406 software with the NX Nastran solver. The numerical results were compared with analytical predictions from the Volkersen and Goland–Reissner models. Full article

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

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43 pages, 9117 KB

Open AccessArticle

A Guide for Industrial Needleless Electrospinning of Synthetic and Hybrid Nanofibers

by Baturalp Yalcinkaya and Matej Buzgo

Polymers 2025, 17(22), 3019; https://doi.org/10.3390/polym17223019 - 13 Nov 2025

Abstract

This study presents a comprehensive investigation into the large-scale production of synthetic and hybrid (nanoparticle-loaded) nanofibers using needleless electrospinning. A diverse range of polymers, including polyamide 6 (PA6) and its other polymer combinations, recycled PA6, polyamide 11 (PA11), polyamide 12 (PA12), polyvinyl butyral [...] Read more.

This study presents a comprehensive investigation into the large-scale production of synthetic and hybrid (nanoparticle-loaded) nanofibers using needleless electrospinning. A diverse range of polymers, including polyamide 6 (PA6) and its other polymer combinations, recycled PA6, polyamide 11 (PA11), polyamide 12 (PA12), polyvinyl butyral (PVB), polycaprolactone (PCL), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyurethane (PU), polyvinyl alcohol (PVA), and cellulose acetate (CA), were utilized to fabricate nanofibers with tailored properties such as polymer solution concentrations and various solvent systems. Furthermore, an extensive variety of nano- and micro-particles, including TiO₂, ZnO, MgO, CuO, Ag, graphene oxide, CeO₂, Er₂O₃, WO₃, MnO₂, and hyperbranched polymers, were incorporated into the polymeric systems to engineer multifunctional nanofibers with enhanced structural characteristics. The study examines the impact of polymer–nano/micro-particle interactions, fiber morphology, and the feasibility of large-scale production via needleless electrospinning. The resulting nanofibers exhibited diameters starting from 80 nm, depending on the polymer and processing conditions. The incorporation of TiO₂, CeO₂, WO₃, Ag, and ZnO nanoparticles into 15% PA6 solutions yielded well-dispersed hybrid nanofibers. By providing insights into polymer selection, nano- and micro-particle integration, and large-scale production techniques, this work establishes a versatile platform for scalable hybrid nanofiber fabrication, paving the way for innovative applications in nanotechnology and materials science. Full article

(This article belongs to the Special Issue Fiber Spinning Technologies and Functional Polymer Fiber Development)

14 pages, 1542 KB

Open AccessArticle

Analysis of the Hertz Contact Model for Evaluating Mechanical Properties of Polymers Using the Finite Element Method

by Laisvidas Striska, Rokas Astrauskas, Nikolajus Kozulinas, Dainius Udris, Sonata Tolvaisiene, Eugenijus Macerauskas, Inga Morkvenaite and Arunas Ramanavicius

Polymers 2025, 17(22), 3018; https://doi.org/10.3390/polym17223018 - 13 Nov 2025

Abstract

Atomic force microscopy (AFM) is widely used to quantify mechanical properties, typically Young’s modulus, by fitting force–indentation data with various mathematical contact models. However, results across laboratories often diverge, and the causes remain unresolved. Here, we interrogate the methodology by which mechanical properties [...] Read more.

Atomic force microscopy (AFM) is widely used to quantify mechanical properties, typically Young’s modulus, by fitting force–indentation data with various mathematical contact models. However, results across laboratories often diverge, and the causes remain unresolved. Here, we interrogate the methodology by which mechanical properties are defined in AFM indentation and identify key limitations of the Hertz model, the standard model for determining mechanical properties, notably that the contact radius is not directly determined, which limits the accuracy of the estimated Young’s modulus. We hypothesize that this inference systematically overestimates the true tip–sample contact, which inflates the contact area and thereby underestimates Young’s modulus. This bias is amplified under large indentation conditions, which are frequently used in soft-material studies. To isolate and clarify the issue, we focus on a well-characterized polymer, polyvinyl chloride (PVC), using it as a controlled testbed for contact radius overestimation. Our analysis is focused on the contact radius and Hertz-based extraction of Young’s modulus. We determined the contact radius and Young’s modulus using AFM with two different probes: a sphere with a 20 nm radius (SPHERE20) and a sphere with a 2 µm radius (SPHERE2000). The results were compared to macroscopic data obtained using a standard measurement (ISO 527-1:2019) of Young’s modulus. The contact was modeled using finite element analysis (FEA). The dependence of the contact radius on the indentation was compared to the Hertz model. The results from FEA fit corrected contact radius values, and it is smaller by 15.46% (SPHERE20) and 57.9% (SPHERE2000) than those calculated by the Hertz model. Full article

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

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