Polymers

16 pages, 3441 KiB

Open AccessArticle

Utilization of Waste Rubber Materials After the End of Their Life Cycle in the Production of Three-Layer Particleboards—Physical and Mechanical Properties

by Vladimír Mancel, Iveta Čabalová, Jozef Krilek, Çağrı Olgun, Mustafa Öncel, Önder Tor, Tomasz Szul, Grzegorz Woroniak and Joanna Piotrowska-Woroniak

Polymers 2025, 17(7), 998; https://doi.org/10.3390/polym17070998 - 7 Apr 2025

Viewed by 382

Abstract

The aim of the article was to test new types of rubber-containing particleboards created from waste materials, which positively contributes to environmental protection, saving primary resources and reducing production costs. This article focuses on the study of three-layer particleboards made from wood particles [...] Read more.

The aim of the article was to test new types of rubber-containing particleboards created from waste materials, which positively contributes to environmental protection, saving primary resources and reducing production costs. This article focuses on the study of three-layer particleboards made from wood particles (spruce non-treated beams) and waste rubber granulates (tires, mixture of seals and carpets, internal flammable cables, external non-flammable cables). Urea–formaldehyde glue, melamine–formaldehyde glue, paraffin emulsion, and ammonium nitrate were used as a binders and excipients in the manufacturing of particleboards. In the core layer of each particleboard, 10% of the weight was made up of rubber granulate. Physical properties (density, water absorption, thickness swelling) and mechanical properties (internal bonding strength, modulus of rupture, modulus of elasticity, screw driving torque) were assessed from this perspective using current EN technical standards. According to the findings, the average densities of all particleboards were comparable to each other in a range from 0.692 to 0.704 g·cm⁻³. The lowest average water absorption and thickness swelling reached particleboards containing 10% of waste internal flammable cables, namely 32.79% for water absorption and 13.21% for thickness swelling. The highest average internal bonding strength reached particleboards without rubber filler and particleboards containing 10% of waste external non-flammable cables, namely 0.52 MPa for both types. The highest average modulus of rupture reached particleboards without rubber filler, namely 12.44 MPa. The highest average modulus of elasticity reached particleboards containing 10% of waste internal flammable cables, namely 2206.29 MPa, and the highest screw driving torque reached particleboards without rubber filler, namely 0.46 N·m for seating torque and 1.44 N·m for stripping torque. The results show that particleboards containing waste external non-flammable cables and particleboards containing waste internal flammable cables achieved comparable results to particleboards without rubber filler, which provides a good basis for a new way of utilizing this type of waste in the form of producing new wood–rubber composites. Full article

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

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21 pages, 78310 KiB

Open AccessArticle

Effect of Laser Power on Formation and Joining Strength of DP980-CFRP Joint Fabricated by Laser Circle Welding

by Sendong Ren, Yihao Shen, Taowei Wang, Hao Chen, Ninshu Ma and Jianguo Yang

Polymers 2025, 17(7), 997; https://doi.org/10.3390/polym17070997 - 7 Apr 2025

Viewed by 226

Abstract

In the present research, laser circle welding (LCW) was proposed to join dual-phase steel (DP980) and carbon fiber-reinforced plastic (CFRP). The welding appearance, cross-section of the welded joint and fracture surfaces were subjected to multi-scale characterizations. Joining strength was evaluated by the single-lap [...] Read more.

In the present research, laser circle welding (LCW) was proposed to join dual-phase steel (DP980) and carbon fiber-reinforced plastic (CFRP). The welding appearance, cross-section of the welded joint and fracture surfaces were subjected to multi-scale characterizations. Joining strength was evaluated by the single-lap shear test. Moreover, a numerical model was established based on the in-house finite element (FE) code JWRIAN-Hybrid to reproduce the thermal process of LCW. The results showed that successful bonding was achieved with a laser power higher than 300 W. The largest joining strength increased to about 1353.2 N (12.2 MPa) with 450 W laser power and then decreased under higher heat input. While the welded joint always presented brittle fracture, the joining zone could be divided into a squeezed zone (SZ), molten zone (MZ) and decomposition zone (DZ). The morphology of CFRP and chemical bonding information were distinct in each subregion. The chemical reaction between the O-C=O bond on the CFRP surface and the -OH bond on the DP980 sheet provided the joining force between dissimilar materials. Additionally, the developed FE model was effective in predicting the interfacial maximum temperature distribution of LCW. The influence of laser power on the joining strength of LCW joints was dualistic in character. The joining strength variation reflected the competitive result between joining zone expansion and local bonding quality change. Full article

(This article belongs to the Special Issue Advanced Joining Technologies for Polymers and Polymer Composites)

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20 pages, 6268 KiB

Open AccessArticle

Theoretical Investigation of Photon Interaction and X-Ray Imaging Performance of PEEK-Based Composites for Medical Implants

by Hanan Akhdar

Polymers 2025, 17(7), 996; https://doi.org/10.3390/polym17070996 - 7 Apr 2025

Viewed by 170

Abstract

Polyetheretherketone (PEEK) is a high-performance, biocompatible polymer with remarkable mechanical properties, making it a promising candidate for medical implants. However, its intrinsic radiolucency poses a challenge for post-operative imaging. This study investigates the photon shielding capabilities and X-ray imaging qualities of pure PEEK [...] Read more.

Polyetheretherketone (PEEK) is a high-performance, biocompatible polymer with remarkable mechanical properties, making it a promising candidate for medical implants. However, its intrinsic radiolucency poses a challenge for post-operative imaging. This study investigates the photon shielding capabilities and X-ray imaging qualities of pure PEEK and its composites with barium sulfate (BaSO₄), tantalum (Ta), bismuth oxide (Bi₂O₃), and hydroxyapatite (HA). The Monte Carlo-based Geant4 toolkit and the EpiXS application were used to evaluate key photon interaction parameters, including mass attenuation coefficients, effective atomic number (Z_eff), and effective electron density (N_eff), as well as the imaging performance metrics such as energy deposition and signal-to-noise ratio (SNR). Results indicate that high atomic number composites significantly enhance PEEK’s photon attenuation and imaging contrast. PEEK-Bi₂O₃ exhibited the highest attenuation coefficients and energy deposition, making it the most effective X-ray shielding material. PEEK-Ta provided a balanced performance with enhanced shielding and lower secondary radiation effects, making it suitable for applications requiring both radiopacity and imaging stability. PEEK-BaSO₄ moderately improved attenuation while maintaining a lower density, offering a trade-off between radiopacity and mechanical properties. Conversely, PEEK-HA demonstrated minimal enhancement in photon attenuation, limiting its effectiveness for radiographic applications. The findings suggest that incorporating high atomic number elements into PEEK significantly enhances its suitability for radiopaque medical implants, allowing for improved post-operative monitoring. Full article

(This article belongs to the Section Polymer Applications)

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12 pages, 3776 KiB

Open AccessArticle

Exploration of the Application of Data-Driven and Generation Models in the Design of Thermoplastic Vulcanizate Rubbers

by Hongyu Yang, Ce Hu, Yanhong Liu and Weimin Yang

Polymers 2025, 17(7), 995; https://doi.org/10.3390/polym17070995 - 7 Apr 2025

Viewed by 242

Abstract

The rapid advancement of big data and artificial intelligence has highlighted the substantial potential of data-driven approaches in polymer material research and development. In the present study, data-driven predictive models were developed to accurately forecast the density, tensile strength, flexural strength and melt [...] Read more.

The rapid advancement of big data and artificial intelligence has highlighted the substantial potential of data-driven approaches in polymer material research and development. In the present study, data-driven predictive models were developed to accurately forecast the density, tensile strength, flexural strength and melt mass flow rate of thermoplastic vulcanizate (TPV) rubber. Furthermore, a generation model was used to produce new material formula data for TPV rubber, and predictions were made for the aforementioned properties. The results indicated that the predicted values are in good agreement with experimental data. This study introduces innovative strategies and methodologies for the intelligent design of polymer materials, which could potentially lower research and development costs and accelerate the emergence of novel materials. Full article

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

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14 pages, 3064 KiB

Open AccessArticle

One-Step Synergistic SDS-H₂O₂ Process for High-Purity Chitin Extraction from Fly Larvae

by Yuhuan Qiu, Zhongtao Zhao, Feng Hu, Mengyi Liu and Xiaowen Shi

Polymers 2025, 17(7), 994; https://doi.org/10.3390/polym17070994 - 7 Apr 2025

Viewed by 247

Abstract

This study develops an efficient method for chitin extraction from fly larvae using a synergistic sodium dodecyl sulfate (SDS)-hydrogen peroxide (H₂O₂) system. Through a three-factor orthogonal experimental design, the optimal conditions were determined as 7% H₂O₂ [...] Read more.

This study develops an efficient method for chitin extraction from fly larvae using a synergistic sodium dodecyl sulfate (SDS)-hydrogen peroxide (H₂O₂) system. Through a three-factor orthogonal experimental design, the optimal conditions were determined as 7% H₂O₂, 80 °C, and 15% SDS, achieving 97.93% deproteinization and 95.66% lipid removal efficiencies. Comparative analyses revealed that the SDS-H₂O₂ system outperformed traditional alkaline and deep eutectic solvent treatments in both purification performance and structural preservation. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) confirmed the high purity and crystallinity of the extracted chitin. Chitin prepared by this method demonstrated good Pb²⁺ adsorption (99.91%), highlighting its potential for targeted heavy metal remediation. Full article

(This article belongs to the Special Issue Advances in Natural Polymers and Active Compounds: Extraction Methods and Applications)

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16 pages, 1523 KiB

Open AccessArticle

Hardness and Roughness of Glass/Epoxy Composite Laminates Subjected to Different Hostile Solutions: A Comparative Study

by Ana Martins Amaro, M. F. Paulino, Maria Augusta Neto and Paulo N. B. Reis

Polymers 2025, 17(7), 993; https://doi.org/10.3390/polym17070993 - 7 Apr 2025

Viewed by 243

Abstract

This work aims to compare the hardness (H) and roughness (R_a) of glass/epoxy composites after being exposed to various hostile environments, which is possible because the constituents are always the same. Considering the stacking sequence [45₂, 90₂, [...] Read more.

This work aims to compare the hardness (H) and roughness (R_a) of glass/epoxy composites after being exposed to various hostile environments, which is possible because the constituents are always the same. Considering the stacking sequence [45₂, 90₂, −45₂, 0₂]_s, the hardness increases for all solutions up to a certain exposure time, from which it decreases for longer immersion times. For the same stacking sequence, roughness had its highest increase (around 44.5%) for the alkaline solution after 36 days of immersion, while the highest decrease (around 25%) occurred for all mortars after 30 days of exposure. For the stacking sequence [0₂, 90₂]_2s, the hardness varied in the opposite direction for acidic and alkaline solutions, observing a direct increase in H with immersion time. However, for samples immersed in oil, hardness decreased as a function of immersion time. In terms of roughness, there was a linear increase with immersion time for all samples, which increased linearly. Therefore, it can be concluded that the stacking sequence has a significant influence on hardness and roughness. Furthermore, knowledge of the variation in hardness and roughness is very important because it can be associated with the structural response of a composite exposed to hostile environments. Full article

(This article belongs to the Special Issue Advancements in the Development of Polymer Composites: Design, Fabrication, Properties and Application)

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22 pages, 2381 KiB

Open AccessArticle

Modeling the Kinetics of Polyethylene Terephthalate and Polyesters with Terminal Hydroxyl Groups Transesterification Reactions

by Kirill A. Kirshanov, Roman V. Toms, Gadir Sh. Aliev, Daniil A. Ismaylov, Natalya Yu. Shagina, Pavel V. Sokolovskiy, Guliya R. Nizameeva and Alexander Yu. Gervald

Polymers 2025, 17(7), 992; https://doi.org/10.3390/polym17070992 - 6 Apr 2025

Viewed by 269

Abstract

Interchain exchange, proceeded by the transesterification mechanism, allows one to obtain polyethylene terephthalate-based polyester products, bypassing the stage of molecular weight reduction and polycondensation used in classical methods of chemical recycling. A kinetic model is presented, which describes the change in the concentrations [...] Read more.

Interchain exchange, proceeded by the transesterification mechanism, allows one to obtain polyethylene terephthalate-based polyester products, bypassing the stage of molecular weight reduction and polycondensation used in classical methods of chemical recycling. A kinetic model is presented, which describes the change in the concentrations of bound and terminal units of ethylene glycol from PET and glycol from another polyester, as well as free molecules of ethylene glycol and another glycol, during transesterification reactions for the first time. Experimental data on the dependence of the degree of randomness and conversion on timeduring the interaction of polyethylene terephthalate and oligodiethylene terephthalate with terminal hydroxyl groups with a number-average molecular weight of 860 g/mol in different ratios were obtained. Molecular weight characteristics of the products of PET and oligoesters with hydroxyl end group interchain exchange, with number-average molecular weights from 610 to 860 g/mol, were also investigated. The simulation results were also compared with published data on the dependence of the degree of randomness and conversion on time during ether exchange in PET/PEN blends. The developed kinetic model was found to be in agreement with the experimental data. Full article

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

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22 pages, 6246 KiB

Open AccessArticle

Structure and Property Evolution of Microinjection Molded PLA/PCL/Bioactive Glass Composite

by Meiqiong Chen, Yinghong Chen, Haihao He, Xinwen Zhou and Ning Chen

Polymers 2025, 17(7), 991; https://doi.org/10.3390/polym17070991 - 6 Apr 2025

Viewed by 219

Abstract

In this study, the microinjection molding technology was adopted to prepare polylactic acid (PLA)/polycaprolactone (PCL)/bioactive glass (BG) composites with varying BG contents for biomedical applications. The various measurement techniques, including scanning electronic microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, the [...] Read more.

In this study, the microinjection molding technology was adopted to prepare polylactic acid (PLA)/polycaprolactone (PCL)/bioactive glass (BG) composites with varying BG contents for biomedical applications. The various measurement techniques, including scanning electronic microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, the water contact angle (WCA) test, the mechanical test, and in vitro biological evaluations, were applied to characterize the above interesting biocomposites. The experimental results show that the extremely strong shear force field generated during the microinjection molding process could induce the in situ formation of micron PCL dispersed phase fibril structures and strongly promote the homogeneous dispersion of micron BG filler particles in the PLA/PCL polymer matrix, which therefore leads to a significant improvement in the specific mechanical property of the PLA/PCL/BG composite. For example, with BG fillers content increasing to 10 wt%, the Young’s modulus of the above obtained PLA/PCL/BG composite could reach 2122.9 MPa, which is 1.47 times higher than that of the unfilled PLA/PCL blend material. In addition, it is also found that under the simulated body fluid (SBF) environment, the incorporated BG fillers in the PLA/PCL polymer matrix could be effectively transformed into hydroxyapatite (HA) components on the treated sample surface, thus being greatly advantageous to enhancing the material’s in vitro bioactivity. Obviously, the microinjection molded PLA/PCL/BG biocomposites could exhibit excellent comprehensive performance, revealing that the microinjection molding processing method could hold great potential in industrialization applications of the resulting biodegradable biomedical materials. Full article

(This article belongs to the Special Issue Advanced Processing Strategy for Functional Polymer Materials)

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19 pages, 5914 KiB

Open AccessArticle

A Comparative Analysis of Mechanical Properties in Injection Moulding (IM), Fused Filament Fabrication (FFF), and Arburg Plastic Freeforming (APF) Processes

by Caolan Jameson, Declan M. Devine, Gavin Keane and Noel M. Gately

Polymers 2025, 17(7), 990; https://doi.org/10.3390/polym17070990 - 5 Apr 2025

Viewed by 273

Abstract

This study explores the mechanical performance of polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) filaments fabricated using fused filament fabrication (FFF), Arburg plastic freeforming (APF), and injection moulding (IM). A series of controlled experiments, including differential scanning calorimetry (DSC), scanning electron microscopy (SEM), [...] Read more.

This study explores the mechanical performance of polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) filaments fabricated using fused filament fabrication (FFF), Arburg plastic freeforming (APF), and injection moulding (IM). A series of controlled experiments, including differential scanning calorimetry (DSC), scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMA), and mechanical tests, were conducted to evaluate the material’s mechanical, thermal, and chemical properties. The results highlight the influence of process parameters and material choice on the mechanical properties of PC/ABS components. The FFF samples exhibited the highest impact strength (up to 28.82 kJ/m²), attributed to porosity acting as a stress absorber under impact load. However, this same porosity led to a 9.14% and 19.27% reduction in flexural and tensile strength, respectively, compared to the APF samples, where stress concentration effects were more pronounced under flexural loads. APF’s mechanical properties were comparable to those of IM, with the process achieving the highest tensile strength, highlighting its potential for producing robust PC/ABS samples. This study aims to provide valuable insight into the selection of additive manufacturing (AM) processes for PC/ABS components. Full article

(This article belongs to the Section Polymer Applications)

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13 pages, 5041 KiB

Open AccessArticle

A Sustainable Microwave-Assisted Process for Chemical Recycling and the Reuse of Epoxy Resin Matrices

by Fabrizio Cafaro, Francesca Ferrari, Gloria Anna Carallo, Antonio Greco and Alfonso Maffezzoli

Polymers 2025, 17(7), 989; https://doi.org/10.3390/polym17070989 - 5 Apr 2025

Viewed by 239

Abstract

This work presents an optimized and sustainable chemical recycling method for epoxy resin matrices, which uses microwave-assisted reactions to achieve the complete recovery of the matrix without generating waste byproducts. The proposed method employs a green chemistry approach, with hydrogen peroxide (H₂ [...] Read more.

This work presents an optimized and sustainable chemical recycling method for epoxy resin matrices, which uses microwave-assisted reactions to achieve the complete recovery of the matrix without generating waste byproducts. The proposed method employs a green chemistry approach, with hydrogen peroxide (H₂O₂) and tartaric acid (TA) as the eco-friendly reagents. Microwaves are used to activate the chemical reaction, ensuring localized heating, reduced energy consumption, and shorter processing times compared to conventional thermal methods. Unlike most existing recycling processes, which focus on fiber recovery, this study emphasizes the recovery and reuse of the matrix, transforming it into a valuable resource for producing new thermosetting materials. The recovered matrix was characterized using FTIR and H-NMR analyses, confirming the presence of reactive functional groups that enable its reintegration into new composite matrix formulations. The process has also demonstrated environmental benefits and economic advantages due to the absence of any waste and the reduced need for virgin raw materials. This method addresses a critical gap in composite material recycling, paving the way for a circular lifecycle and advancing the principles of sustainability in materials engineering. Full article

(This article belongs to the Special Issue Advances in Polymer Recycling and Upcycling: Toward a Circular and Sustainable Future)

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21 pages, 6575 KiB

Open AccessArticle

The Importance of Crosslinking in Electrospun Membranes for Water Contaminant Removal

by Peio Martinez-Goikoetxea, José Manuel Laza, Julia Sanchez-Bodon, José Luis Vilas-Vilela and Antonio Veloso-Fernández

Polymers 2025, 17(7), 988; https://doi.org/10.3390/polym17070988 - 5 Apr 2025

Viewed by 313

Abstract

Traditional water purification systems often rely on synthetic materials that pose environmental risks due to their non-biodegradability and the potential release of harmful substances. To address these concerns, natural polymer-based membranes are being developed as a sustainable and environmentally friendly alternative for water [...] Read more.

Traditional water purification systems often rely on synthetic materials that pose environmental risks due to their non-biodegradability and the potential release of harmful substances. To address these concerns, natural polymer-based membranes are being developed as a sustainable and environmentally friendly alternative for water treatment due to their biodegradability, low toxicity, and chemical versatility. These materials are particularly suitable for removing a wide range of contaminants due to their high selectivity and water permeability. Despite their benefits, challenges such as improving mechanical strength, durability, and resistance to fouling persist. Ongoing research continues to optimize the performance of electrospun membranes to meet modern water treatment demands. For this purpose, crosslinking via thermal initiators azobisisobutyronitrile (AIBN) and 2,2’-azobis(2-amidinopropane)dihydrochloride (V50) and chemical crosslinking by glutaraldehyde (GA) vapor have been studied for methacrylated chitosan and alginate. In addition, biocharcoal has been introduced into the membranes to enhance their functional properties. The development of natural polymer-based membranes combined with biocharcoal presents a promising and scalable solution for sustainable water purification, playing a crucial role in reducing pollution and preserving vital water resources for future generations. In this study, we demonstrate that the crosslinking effect plays a key role in maintaining the stability of alginate-based membranes in an aqueous environment while enhancing their adsorption capacity for methylene blue dye, making them promising for water purification applications. Full article

(This article belongs to the Special Issue Functional Materials Based on Biodegradable Polymers)

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12 pages, 4732 KiB

Open AccessArticle

Recycling Waste Fiberglass by Powder Grinding and Direct Molding of Powders

by Fabrizio Quadrini, Leandro Iorio, Giorgio Patrizii, Denise Bellisario and Loredana Santo

Polymers 2025, 17(7), 987; https://doi.org/10.3390/polym17070987 - 5 Apr 2025

Viewed by 332

Abstract

Direct molding is a compression molding process of thermoset particles without the addition of any linking agent or binder. It is suitable for recycling end-of-life fiberglass or other waste from the manufacturing of fiberglass products. In this study, for the first time, the [...] Read more.

Direct molding is a compression molding process of thermoset particles without the addition of any linking agent or binder. It is suitable for recycling end-of-life fiberglass or other waste from the manufacturing of fiberglass products. In this study, for the first time, the feasibility of recycling waste fiberglass powder, collected from an industry, is shown in the case of a vinyl ester matrix. Powders have been directly molded, without any pre-treatment such as sieving, to manufacture small samples for four-point bending tests. Supplied powders have been characterized by microscopy and thermal analysis. Its size distribution has been evaluated by sieving, and the amount of resin by burning test. Samples have been compression molded in an eight-cavity mold and have shown good homogeneity and surface aspect. The average density of the recycled fiberglass is 1.23 g/cm³, the bending strength 28 MPa, the elongation at break 1.6%, and the elastic modulus 1.9 GPa, with low dispersion (7% at maximum). Surface analysis has shown a rough surface and the presence of embedded glass fibers into the agglomerated fiberglass. Results show that waste powders from secondary processes of fiberglass manufacturers, such as surface grinding, may provide secondary raw materials for the production of molded parts without mixing with virgin substances. Full article

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

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14 pages, 3921 KiB

Open AccessArticle

High-Permittivity Silicone Composites with Different Polarization Titanates for Electric Field Modification

by Evgeniy Radzivilov, Ilya Zotov, Maria Vikulova, Alexey Tsyganov, Ivan Artyukhov, Denis Artyukhov, Alexander Gorokhovsky, Artem Yudin and Nikolay Gorshkov

Polymers 2025, 17(7), 986; https://doi.org/10.3390/polym17070986 - 4 Apr 2025

Viewed by 284

Abstract

Polymer-matrix composites with ceramic fillers have various applications, one of which is the modification of the electric field. For this purpose, in this work, high-permittivity silicone composites with different polarization titanates were produced by mechanical mixing. The ceramic fillers chosen were CaCu₃ [...] Read more.

Polymer-matrix composites with ceramic fillers have various applications, one of which is the modification of the electric field. For this purpose, in this work, high-permittivity silicone composites with different polarization titanates were produced by mechanical mixing. The ceramic fillers chosen were CaCu₃Ti₄O₁₂, K_xFe_yTi_8−yO₁₆, and BaTiO₃ powders with high permittivity values and uniformly distributed in the polymer volume. Ceramic powders were studied by X-ray phase analysis and scanning electron microscopy methods. The proportion of ceramic powder was 25 wt.%. In parallel, composites were prepared with the addition of 25 wt.% glycerin. The functional properties of silicone composites were studied using the following parameters: the electrical strength and permittivity. The addition of all types of ceramic fillers, both together and without glycerin, led to a decrease in electrical strength (below 15 kV·mm⁻¹); the exception is the sample with the CCTO without glycerin (about 28 kV·mm⁻¹). The permittivity and the dielectric loss tangent of the composites increased as a result of the addition of fillers, especially noticeable in combination with glycerol in the low-frequency region. The obtained results are in good agreement with the literature data and can be used in the field of insulation in a high-permittivity layer to equalize equipotential fields. Full article

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

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17 pages, 6278 KiB

Open AccessArticle

Efficient Removal of Mercury Ions Stabilized by Gold Solution Using Chitosan–Guar Gum Polymer Blend in Basic Media

by Azwifunimunwe Tshikovhi, Shivani B. Mishra, Ajay K. Mishra, Mokgaotsa J. Mochane and Tshwafo E. Motaung

Polymers 2025, 17(7), 985; https://doi.org/10.3390/polym17070985 - 4 Apr 2025

Viewed by 273

Abstract

The highly efficient removal of mercury metal ions at a higher pH (basic media) is barely reported in the literature. In this study, we developed a novel adsorbent by blending chitosan with guar gum, designed to effectively remove mercury ions from basic media [...] Read more.

The highly efficient removal of mercury metal ions at a higher pH (basic media) is barely reported in the literature. In this study, we developed a novel adsorbent by blending chitosan with guar gum, designed to effectively remove mercury ions from basic media by stabilizing them with a gold (Au³⁺) solution. The FTIR confirmed the compatibility of chitosan and guar gum through hydrogen bonding. The morphology of the blend exhibited an amorphous and porous structure. A mesoporous structure with a surface area, volume, and diameter of 11.843 (m²/g), 0.184 (cm²/g), and 17.072 nm, respectively, was confirmed by BET. The adsorption behavior was analyzed using isotherms and kinetics models, which best fitted with the pseudo-second-order kinetic model and Freundlich adsorption isotherm model, respectively. The adsorbent was shown to be an excellent candidate for the removal of mercury ions in water, with an adsorption efficiency of 92% at pH 12 in 60 min and a maximum adsorption capacity of 370.37 (mg/g). Full article

(This article belongs to the Special Issue Advancements in the Development of Polymer Composites: Design, Fabrication, Properties and Application)

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22 pages, 51238 KiB

Open AccessArticle

Effect of Choline Chloride-Based DES on the Pore-Forming Ability and Properties of PVDF Membranes Prepared with Triethyl Phosphate as Green Solvent

by Alejandro Gálvez-Subiela, Ramón Jiménez-Robles, Jose David Badia-Valiente, Marta Izquierdo and Amparo Chafer

Polymers 2025, 17(7), 984; https://doi.org/10.3390/polym17070984 - 4 Apr 2025

Viewed by 189

Abstract

This study explores the influence of various additives on the morphological, chemical, and thermal properties of poly(vinylidene fluoride) (PVDF) membranes prepared via the non-solvent induced phase separation (NIPS) technique. The use of a green solvent such as triethyl phosphate (TEP) was shown to [...] Read more.

This study explores the influence of various additives on the morphological, chemical, and thermal properties of poly(vinylidene fluoride) (PVDF) membranes prepared via the non-solvent induced phase separation (NIPS) technique. The use of a green solvent such as triethyl phosphate (TEP) was shown to be successful. A particular focus was dedicated to pore formers based on choline chloride–based deep eutectic solvents (DES) in combination with ethylene glycol and glycerol, i.e., ChCl/EG and ChCl/GLY, and its benchmark with traditional counterparts such as poly(ethylene glycol) (PEG) and glycerol (GLY). Comprehensive characterization was conducted using FESEM, FTIR, XRD, and DSC techniques to evaluate changes in membrane morphology, porosity, and crystallinity. PEG acted as a pore-forming agent, transitioning the internal structure from spherulitic to sponge-like with consistent pore sizes, while GLY produced a nodular morphology at higher concentrations due to increased dope solution viscosity. DES induced significant shifts in crystalline phase composition, decreasing α-phase fractions and promoting β-phase formation at higher concentrations. While the overall porosity remained unaffected by the addition of GLY or PEG, it was dependent on the DES concentration in the dope at lower values than those obtained by GLY and PEG. Membrane pore size with ChCl/GLY was lower than with ChCl/EG and GLY. All membranes showed performance at the hydrophobic regime. The findings demonstrate that ChCl/EG and ChCl/GLY can tailor the structural and thermal properties of TEP-driven PVDF membranes, providing a green and versatile approach to customize the membrane properties for specific applications. Full article

(This article belongs to the Special Issue Polymeric Membranes: Advances in Synthesis, Characterization and Applications)

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20 pages, 12155 KiB

Open AccessArticle

The Effect of Plasma Treatment on the Mechanical Properties of HDPE/Bamboo Fiber Composites

by Zihan Ma, Yan Wu, Hongyan Wang, Jian Zhang and Shaofei Yuan

Polymers 2025, 17(7), 983; https://doi.org/10.3390/polym17070983 - 4 Apr 2025

Viewed by 292

Abstract

In order to improve the interface compatibility of HDPE/bamboo fiber composites, O₂ and N₂ plasma were used to treat the HDPE surface, the effects of plasma treatment power, time, and different flow rates on HDPE surface wettability were analyzed, the optimal [...] Read more.

In order to improve the interface compatibility of HDPE/bamboo fiber composites, O₂ and N₂ plasma were used to treat the HDPE surface, the effects of plasma treatment power, time, and different flow rates on HDPE surface wettability were analyzed, the optimal process of plasma to improve HDPE surface wettability was determined, and a mathematical model between HDPE surface energy and the plasma treatment process was established. The effect of plasma treatment on the mechanical properties of HDPE/bamboo fiber composites was further studied, and the surface morphology and surface chemical structure of the materials before and after plasma treatment were analyzed. The results show that the surface wettability of HDPE can be significantly improved after O₂ and N₂ plasma treatment, which can further enhance the interface compatibility of HDPE/bamboo fiber composites and improve the impact and tensile strength of the composites (impact strength increased by 19.91% and 19.55% after O₂ and N₂ plasma treatment, respectively; tensile strength increased by 16.47% and 12.48%, respectively). The optimal process parameters for enhancing the interface compatibility of the two plasma composites are 1100 W, 13 s, and 1.75 L/min (O₂ plasma), and 1100 W, 13 s, 2.5 L/min (N₂ plasma); between the two, N₂ plasma has a better effect on the surface wettability of HDPE than O₂ plasma treatment. Full article

(This article belongs to the Special Issue Fibre-Reinforced Polymer Laminates: Structure and Properties)

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16 pages, 4171 KiB

Open AccessArticle

The Impact of Recovered Lignin on Solid-State PEO-Based Electrolyte Produced via Electrospinning: Manufacturing and Characterisation

by Laura Coviello, Giorgia Montalbano, Alessandro Piovano, Nagore Izaguirre, Chiara Vitale-Brovarone, Claudio Gerbaldi and Sonia Fiorilli

Polymers 2025, 17(7), 982; https://doi.org/10.3390/polym17070982 - 4 Apr 2025

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Abstract

Lithium batteries have gained significant attention due to their high energy density, specific capacity, operating voltage, slow self-discharge rate, good cycle stability, and rapid charging capabilities. However, the use of liquid electrolytes presents several safety hazards. Solid-state polymer electrolytes (SPEs) offer a promising [...] Read more.

Lithium batteries have gained significant attention due to their high energy density, specific capacity, operating voltage, slow self-discharge rate, good cycle stability, and rapid charging capabilities. However, the use of liquid electrolytes presents several safety hazards. Solid-state polymer electrolytes (SPEs) offer a promising alternative to mitigate these issues. This study focuses on the preparation of an ionically conductive electrospun membrane and its potential application as an SPE. To support a circular approach and reduce the environmental impact, the target polymeric formulation combines poly(ethylene oxide) (PEO) and lignin, sourced from paper industry waste. The formulation is optimised to ensure the dissolution of lithium salts and enhance the membrane integrity. The addition of lignin is crucial to contrast the dendrites’ growth and prevent the consequent battery breakdown. The electrospinning process is adjusted to obtain stable, homogeneous nanofibrous membranes, which are characterised using electron scanning microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The membranes’ potential as an SPE is assessed by measuring their ionic conductivity (>10⁻⁵ S cm⁻¹ above 50 °C) and anodic stability (≈4.6 V vs. Li/Li⁺), and by testing their compatibility with lithium metal by reversible cycling in a symmetric Li|Li cell at 55 °C. Full article

(This article belongs to the Special Issue From Biomass Fractionation to Final Biobased Polymer Nanocomposites in European Sustainable Biobased Nanomaterials Community (BIOMAC))

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21 pages, 21692 KiB

Open AccessArticle

In Situ Punch–Shear Testing of Polymers

by David Munoz-Paniagua, Ahmed Hammami, Hadi Nazaripoor, Abderrazak Traidia, Jorge Palacios Moreno and Pierre Mertiny

Polymers 2025, 17(7), 981; https://doi.org/10.3390/polym17070981 - 4 Apr 2025

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Abstract

Conventional material aging and testing protocols involve exposing coupon samples to saturation in application fluid(s) at temperature and pressure conditions typically encountered during service, followed by mechanical testing at ambient conditions. This practice can generate misleading results for materials for which fluid ingress [...] Read more.

Conventional material aging and testing protocols involve exposing coupon samples to saturation in application fluid(s) at temperature and pressure conditions typically encountered during service, followed by mechanical testing at ambient conditions. This practice can generate misleading results for materials for which fluid ingress is rapidly reversible, most notably at elevated temperatures. A recently developed in situ punch–shear device has been successfully used to establish experimental correlations between the tensile properties (ASTM D638) and shear properties (ASTM D732) of Polyethylene of Raised Temperature (PERT) under dry conditions. It also enabled measurement of shear properties of select polymers while immersed (saturated) in fluids at elevated pressure and temperature. The present work extends the treatment to a suite of commercially available thermoplastic polymers spanning the commodity, engineering, and high-performance polymer grades with varying degrees of hygroscopicity. The objectives of this contribution are three-fold, namely: (i) assess the effect of sample preparation method on measured mechanical properties, (ii) compare the experimentally established correlations between shear and tensile tests for the different class of polymer grades before fluid exposure, and (iii) gauge reversibility of the measured tensile and shear properties after aging in deionized water to saturation at 95 °C. Results indicate that (i) the test coupon preparation method affects the tensile to shear correlation and must be standardized to enable systematic comparison of in situ properties, (ii) individual correlations segregate by polymer family, and (iii) conventional tensile testing after a saturation–dehydration cycle yields optimistic mechanical properties. Full article

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

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21 pages, 1220 KiB

Open AccessArticle

Tracking the Effect of Phosvitin (PV) Concentration on the Skin Permeation of Somatotropin (STH) from Semi-Solid Hydrogel Formulations

by Wioletta Siemiradzka

Polymers 2025, 17(7), 980; https://doi.org/10.3390/polym17070980 - 4 Apr 2025

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Abstract

Recombinant human growth hormone (rhGH) is utilized in pediatric patients with short stature for a variety of indications, including those in which the primary growth defect is not related to growth hormone deficiency (GHD). However, due to the instability of the hormone in [...] Read more.

Recombinant human growth hormone (rhGH) is utilized in pediatric patients with short stature for a variety of indications, including those in which the primary growth defect is not related to growth hormone deficiency (GHD). However, due to the instability of the hormone in the gastrointestinal tract and its short half-life, an alternative route of administration is being sought, which may be the skin. One strategy to extend the half-life of proteins involves the use of biodegradable polymeric matrices for transdermal drug delivery systems. While hydrogels are recognized for their high stability, the transport of proteins through the skin may be hindered. To address this, the use of active carriers is being investigated to enhance the efficiency of protein permeation through the skin. In this study, an effort was made to optimize the concentration of phosphitin (PV) as a carrier for somatotropin (STH). PV is a protein that possesses a distinctive cation chelating capability and amphiphilic character. As the concentration of PV increased, the rate of its emulsifying activity increased concomitantly. Methylcellulose (MC) was used as the hydrogel matrix. The study investigated three distinct concentrations of PV to ascertain the most optimal concentration to enhance STH availability. Following the formulation of hydrogel compositions containing STH and PV, the permeation process through porcine skin was examined using Franz’s chambers. The findings revealed that the incorporation of PV significantly impacted both the penetration time of STH and the extent of STH penetration. Subsequently, an extensive evaluation of the physicochemical parameters of the formulations, encompassing pH, rheological, and textural properties, was conducted to assess their suitability for skin application. This evaluation aimed to ensure not only adequate persistence time of the formulation on the skin surface but also formulation stability and persistence of the active substance (STH). Full article

(This article belongs to the Special Issue Advanced Biodegradable Polymers for Biomedical Applications)

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15 pages, 3077 KiB

Open AccessArticle

Surface-Driven Phase Segregation in Conducting Polymer Thin Films Enables High Selectivity and Storage Stability of Chemiresistive Sensors in Humid Air

by Jianan Weng, Wei Wu, Minghao Qian, Jiarui Zhang, Shuhua Zhang, Zhi Geng and Bo Zhu

Polymers 2025, 17(7), 979; https://doi.org/10.3390/polym17070979 - 3 Apr 2025

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Abstract

Chemiresistive sensors integrated with functionalized conductive polymers have emerged as promising candidates for wearable applications, offering adequate protection against highly toxic and widely prevalent organophosphate compounds, due to their high sensitivity, room-temperature operation, and straightforward fabrication process. However, these chemiresistive sensors exhibit poor [...] Read more.

Chemiresistive sensors integrated with functionalized conductive polymers have emerged as promising candidates for wearable applications, offering adequate protection against highly toxic and widely prevalent organophosphate compounds, due to their high sensitivity, room-temperature operation, and straightforward fabrication process. However, these chemiresistive sensors exhibit poor resistance to water vapor due to the intrinsic properties of these conducting polymers, likely leading to false sensor alarms. In this study, we engineered a series of water-vapor-resistant, yet organophosphate-sensitive, conducting polymers by electro-copolymerizing hexafluoroisopropanol (HFIP)-grafted 3,4-ethylenedioxythiophene (EDOT-HFIP) with EDOT comonomers bearing hydrophobic alkyl groups of varying lengths (ethyl, butyl, and hexyl). The typical results indicated that increasing the alkyl length and alkyl-bearing EDOT comonomer composition significantly enhanced the water resistance of the EDOT-HFIP copolymers and the copolymer-integrated chemiresistive sensor, but this improvement came at the unacceptable cost of compromising the organophosphate sensitivity. To address this issue, we developed a surface-driven phase-segregation strategy to enrich the alkyl chains on the surface while concentrating the HFIP groups beneath it by treating the silica substrates using oxygen plasma before polymer spin coating, thus decoupling and optimizing the two mutually competing characteristics. Finally, the chemiresistive sensor integrated with the EDOT-HFIP copolymer containing 10% hexyl-grafted EDOT comonomer exhibited an organophosphate (DMMP) resistive response 657 times higher than that to water vapor, and more than two times that of a PEDOT-HFIP sensor, while preserving the original specific sensitivity of the PEDOT-HFIP sensor. Furthermore, it demonstrated a markedly improved shelf storage stability, being directly exposed to air for 14 days without any special protection. We envision that this surface-driven phase-segregation strategy could offer a promising solution to the significant challenge of air moisture interference in highly sensitive polymer sensors, promoting their practical use in real-world applications. Full article

(This article belongs to the Special Issue Polymers and Polymer Composites: Structure-Property Relationship, 2nd Edition)

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16 pages, 15423 KiB

Open AccessArticle

Monte Carlo Simulations of Polymer Collapse in an Explicit Solvent of Varying Quality

by Piotr Polanowski and Andrzej Sikorski

Polymers 2025, 17(7), 978; https://doi.org/10.3390/polym17070978 - 3 Apr 2025

Viewed by 181

Abstract

The behavior of a single homopolymer chain in an explicit solvent in a wide range of poor and good solvents was investigated. For this purpose, a two-dimensional coarse-grained model based on a triangular lattice was used. Simulations were carried out by the Monte [...] Read more.

The behavior of a single homopolymer chain in an explicit solvent in a wide range of poor and good solvents was investigated. For this purpose, a two-dimensional coarse-grained model based on a triangular lattice was used. Simulations were carried out by the Monte Carlo method using the Cooperative Motion Algorithm to study high-density systems. The scaling relations of the parameters describing the phase transitions of the chain were determined. For systems with polymer–solvent attraction, significant changes in chain size and shape were observed. This was associated with the mechanism of chain penetration by solvents and the formation of structures via a mechanism called ‘Bridging-Induced Attraction’, similar to those discovered for three dimensions. Full article

(This article belongs to the Special Issue Polymer Brushes: Synthesis, Characterization and Applications)

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23 pages, 8937 KiB

Open AccessArticle

Robust Composites Based on Silicone Rubber for Self-Powered Piezoelectric Nanogenerators

by Vineet Kumar, Md Najib Alam, Siraj Azam and Sang Shin Park

Polymers 2025, 17(7), 977; https://doi.org/10.3390/polym17070977 - 3 Apr 2025

Viewed by 262

Abstract

Obtaining robust power density through piezoelectric nanogenerators (PENGs) is very challenging. Challenges include achieving good mechanical stability, optimum stiffness, reasonable voltage generation, limited heat dissipation, and power density as needed. This work focused exactly on these areas, and hybrid filler emerged as a [...] Read more.

Obtaining robust power density through piezoelectric nanogenerators (PENGs) is very challenging. Challenges include achieving good mechanical stability, optimum stiffness, reasonable voltage generation, limited heat dissipation, and power density as needed. This work focused exactly on these areas, and hybrid filler emerged as a promising candidate among the composites studied. For example, hybrid fillers exhibited optimized properties suitable for self-powered engineering applications. The composites fabricated in this work were based on titanium oxide (TiO₂), molybdenum disulfide (MoS₂), and silicone rubber (SR) as a host matrix. The results showed that TiO₂ represents a good reinforcing filler, while MoS₂ exerts a lubricating effect, improving the composites’ mechanical strength and elongation at break. For example, the compressive modulus at 8 per hundred parts of rubber (phr) was 2.39 MPa (TiO₂), 1.62 MPa (MoS₂), and 2.1 MPa (hybrid filler). Similarly, the hysteresis loss at 5 phr was 20.09 J/m (TiO₂), 21.56 J/m (MoS₂), and 20.48 J/m (hybrid filler). Moreover, the elongation at break at 8 phr was 150% (TiO₂), 194% (MoS₂), and 170% (hybrid filler). In the same way, the electro-mechanical properties obtained were also robust. For example, the voltage output was ~22 mV (TiO₂), ~35 mV (MoS₂), and ~46 mV (hybrid filler). Moreover, the PENGs developed in this work generated power. For example, the power density was ~0.55 pW/cm² (TiO₂), ~1.03 pW/cm² (MoS₂), and ~1.56 pW/cm² (hybrid filler). Finally, the piezoelectric coefficient of the PENGs was 40 pC/N (TiO₂), 112 pC/N (MoS₂), and 160 pC/N (hybrid filler). These materials have a promising role in energy harvesting through self-powered nanogenerators for portable electronic systems. Finally, the low-power PENGs developed provide cost-effective voltage and power management circuits. This allows these PENGs to contribute to sustainable and self-sufficient electronic systems like pacemaker implants. Full article

(This article belongs to the Special Issue Multifunctional Polymer Composite Materials, 2nd Edition)

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15 pages, 3364 KiB

Open AccessArticle

Predictive Modeling of Shear Strength of Enzyme-Induced Calcium Carbonate Precipitation (EICP)-Solidified Rubber–Clay Mixtures Using Machine Learning Algorithms

by Qiang Ma, Meng Li, Hang Shu and Lei Xi

Polymers 2025, 17(7), 976; https://doi.org/10.3390/polym17070976 - 3 Apr 2025

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Abstract

The development of reliable predictive models for soil behavior represents a crucial advancement in geotechnical engineering, particularly for optimizing material compositions and reducing experimental uncertainties. Traditional experimental approaches for determining the optimal rubber particle size and content are often resource-intensive, time-consuming, and subject [...] Read more.

The development of reliable predictive models for soil behavior represents a crucial advancement in geotechnical engineering, particularly for optimizing material compositions and reducing experimental uncertainties. Traditional experimental approaches for determining the optimal rubber particle size and content are often resource-intensive, time-consuming, and subject to significant variability. In this study, the shear strength of clay mixed with rubber particles solidified by the Enzyme-Induced Calcium Carbonate Precipitation (EICP) technique was investigated and predictively modeled using a machine learning algorithm. The effects of different rubber contents and particle sizes on the shear strength of the clay were analyzed experimentally, and a hybrid model of a convolutional neural network (CNN) and long short-term memory (LSTM) network optimized based on the crown porcupine optimization (CPO) algorithm was proposed to predict the shear strength of the EICP-treated clay mixed with rubber particles. The superiority of the CPO-CNN-LSTM model in predicting shear strength was verified by comparing multiple machine learning algorithms. The results show that the addition of rubber particles significantly improves the shear strength of the clay, especially at a 5% rubber content. The coefficient of determination (R²) of the CPO-CNN-LSTM model on the training and test datasets reaches 0.98 and 0.97, respectively, which exhibit high prediction accuracy and generalization ability. Full article

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

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25 pages, 12073 KiB

Open AccessArticle

Exosome-Seeded Cryogel Scaffolds for Extracellular Matrix Regeneration in the Repair of Articular Cartilage Defects: An In Vitro and In Vivo Rabbit Model Study

by Daniel Yang, Joseph Yang, Shwu-Jen Chang, Jhe-Lun Hu, Yong-Ji Chen and Shan-Wei Yang

Polymers 2025, 17(7), 975; https://doi.org/10.3390/polym17070975 - 3 Apr 2025

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Abstract

Traumatic or degenerative defects of articular cartilage impair joint function, and the treatment of articular cartilage damage remains a challenge. By mimicking the cartilage extracellular matrix (ECM), exosome-seeded cryogels may enhance cell proliferation and chondral repair. ECM-based cryogels were cryopolymerized with gelatin, chondroitin [...] Read more.

Traumatic or degenerative defects of articular cartilage impair joint function, and the treatment of articular cartilage damage remains a challenge. By mimicking the cartilage extracellular matrix (ECM), exosome-seeded cryogels may enhance cell proliferation and chondral repair. ECM-based cryogels were cryopolymerized with gelatin, chondroitin sulfate, and various concentrations (0%, 0.3%, 0.5%, and 1%) of hyaluronic acid (HA), and their water content, swelling ratio, porosity, mechanical properties, and effects on cell viability were evaluated. The regenerative effects of bone marrow-derived mesenchymal stem cell (BM-MSC)-derived exosome (at a concentration of 10⁶ particles/mL)-seeded 0.3% HA cryogels were assessed in vitro and in surgically induced male New Zealand rabbit cartilage defects in vivo. The water content, swelling ratio, and porosity of the cryogels significantly (p < 0.05) increased and the Young’s modulus values of the cryogels decreased with increasing HA concentrations. MTT assays revealed that the developed biomaterials had no cytotoxic effects. The optimal cryogel composition was 0.3% HA, and the resulting cryogel had favorable properties and suitable mechanical strength. Exosomes alone and exosome-seeded cryogels promoted chondrocyte proliferation (with cell optical densities that were 58% and 51% greater than that of the control). The cryogel alone and the exosome-seeded cryogel facilitated ECM deposition and sulfated glycosaminoglycan synthesis. Although we observed cartilage repair via Alcian blue staining with both the cryogel alone and the exosome-seeded cryogel, the layered arrangement of the chondrocytes was superior to that of the control chondrocytes when exosome-seeded cryogels were used. This study revealed the potential value of using BM-MSC-derived exosome-seeded ECM-based cryogels for cartilage tissue engineering to treat cartilage injury. Full article

(This article belongs to the Special Issue Advances in Synthesis and Application of Biomedical Polymer Materials)

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15 pages, 7482 KiB

Open AccessArticle

Biocomposites Based on PHBV and the Lignocellulosic Residue from Horchata Production

by Anita Patrón-Espá, María Eugenia Martín-Esparza, Amparo Chiralt and Chelo González-Martínez

Polymers 2025, 17(7), 974; https://doi.org/10.3390/polym17070974 - 3 Apr 2025

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Abstract

The use of agro-industrial residues in the development of packaging materials is a topic of interest from a sustainable perspective, as it promotes biodegradability, reduces production costs, and aligns with the concept of a circular economy. The aim of this work was to [...] Read more.

The use of agro-industrial residues in the development of packaging materials is a topic of interest from a sustainable perspective, as it promotes biodegradability, reduces production costs, and aligns with the concept of a circular economy. The aim of this work was to develop and characterize biodegradable composite films based on Poly 3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) and the tiger nut horchata solid residue (HSR) at different ratios. The obtained composites were evaluated as to their suitability as food active packaging materials in terms of microstructure, water content and solubility, mechanical, barrier and thermal properties, and total phenolic content and antioxidant capacity. The incorporation of HSR into the PHBV matrix led to more opaque, darker reddish films and promoted significant changes in their mechanical and barrier properties. Specifically, the composite films showed lower water vapor barrier capacity and reduced tensile strength (43–81% lower TS) and elongation at break (46–77% lower Ɛ values) while the rigidity increased or maintained when using up to 20% wt. of HSR. In contrast, the incorporation of the HSR provided the films with remarkable antioxidant capacity and effective light-blocking capacity, which could be of great interest for food preservation, as active packaging materials. The total phenol content of the composites increased in line with the increment of the HSR content, ranging from 9 to 34 mg GAE/100 g film. Full article

(This article belongs to the Special Issue State-of-the-Art Cellulose and Renewable Materials)

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2 pages, 137 KiB

Open AccessRetraction

RETRACTED: El-Hamshary et al. Preparation and Characterization of Nanofibrous Scaffolds of Ag/Vanadate Hydroxyapatite Encapsulated into Polycaprolactone: Morphology, Mechanical, and In Vitro Cells Adhesion. Polymers 2021, 13, 1327

by Hany El-Hamshary, Mehrez E. El-Naggar, Ayman El-Faham, M. A. Abu-Saied, M. K. Ahmed and Mosaed Al-Sahly

Polymers 2025, 17(7), 973; https://doi.org/10.3390/polym17070973 - 3 Apr 2025

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Abstract

The journal retracts the article titled “Preparation and Characterization of Nanofibrous Scaffolds of Ag/Vanadate Hydroxyapatite Encapsulated into Polycaprolactone: Morphology, Mechanical, and In Vitro Cells Adhesion” [...] Full article

(This article belongs to the Section Polymer Applications)

13 pages, 5182 KiB

Open AccessArticle

High Thermoelectric Performance of Flexible and Free-Standing Composite Films Enabled by 3D Inorganic Ag₂Se Conductive Networks Filled with Organic PVDF

by Zishuo Xu, Yuejuan Hu, Yuchen Hu, Xianfeng Xiao and Qin Yao

Polymers 2025, 17(7), 972; https://doi.org/10.3390/polym17070972 - 3 Apr 2025

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Abstract

Herein, a flexible and free-standing (substrate-free) PVDF/Ag₂Se (Polyvinylidene fluoride) composite film was successfully fabricated through a combination of drop-casting and heat treatment. It was observed that when the drop-casted PVDF/Ag₂Se composite film was heated above the melting point of [...] Read more.

Herein, a flexible and free-standing (substrate-free) PVDF/Ag₂Se (Polyvinylidene fluoride) composite film was successfully fabricated through a combination of drop-casting and heat treatment. It was observed that when the drop-casted PVDF/Ag₂Se composite film was heated above the melting point of PVDF, the small and separated Ag₂Se crystalline grains in the composite film grow and interconnect to form a three-dimensional (3D) conductive network to increase the carrier mobility, while the molten PVDF effectively fills the network voids to enhance the flexibility and mechanical strength. As a result, both the electrical conductivity and Seebeck coefficient of the composite films were significantly enhanced after heat treatment. The power factor of the PVDF/Ag₂Se composite with a mass ratio of 1:4 at room temperature reached 488.8 μW m⁻¹ K⁻², among the best level of Ag₂Se- or PVDF-based flexible and free-standing composite films. Bending tests demonstrated the superior flexibility of the hybrid film, with the electrical conductivity decreasing by only 10% after 1000 bending cycles. Additionally, a five-leg thermoelectric device achieved an impressive output power density of 1.75 W m⁻² at a temperature difference (∆T) of 30 K. This study proposes an innovative strategy to enhance the thermoelectric performance and free-standing capability of organic-inorganic composite films, while achieving a competitive power factor and advancing the practical application of flexible thermoelectric devices. Full article

(This article belongs to the Special Issue Conductive Polymers for Electronic Devices, Displays and Sensors)

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23 pages, 7985 KiB

Open AccessArticle

Development and Characterization of PBS/EA Cellulose and PCL/EA Cellulose Biocomposites: Structural, Morphological, and Thermal Insights for Sustainable Applications

by Fisokuhle Innocentia Kumalo, Moipone Alice Malimabe, Mafereka Francis Tyson Mosoabisane and Thandi Patricia Gumede

Polymers 2025, 17(7), 971; https://doi.org/10.3390/polym17070971 - 2 Apr 2025

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Abstract

This study investigates the effect of Eucomis autumnalis (EA) cellulose on the structural, thermal, and crystallization behaviour of polybutylene succinate (PBS) and polycaprolactone (PCL) composites. X-ray diffraction (XRD) results showed that in both matrices, EA cellulose promoted nucleation, as indicated by increased peak [...] Read more.

This study investigates the effect of Eucomis autumnalis (EA) cellulose on the structural, thermal, and crystallization behaviour of polybutylene succinate (PBS) and polycaprolactone (PCL) composites. X-ray diffraction (XRD) results showed that in both matrices, EA cellulose promoted nucleation, as indicated by increased peak intensity, while differential scanning calorimetry (DSC) showed reduced melting enthalpy, suggesting the formation of smaller, less perfect crystals. In PBS composites, EA cellulose acted as a crystallization disruptor, reducing crystallinity and enthalpy. Moreover, it slightly lowered the melting temperature. This is because EA cellulose contains β-(1→4) glycosidic bonds, which introduce –O– (ether) linkages along its polymer backbone. These linkages allow for a degree of rotational flexibility. When the cellulose is incorporated into PBS, this structural characteristic may contribute to a reduction in T_m, likely by disrupting the crystallization of PBS chains. At 1 wt.% EA cellulose, broader, more intense melting peaks indicated imperfect crystal formation, while higher loadings (3 and 5 wt.%) resulted in narrower, less intense peaks, reflecting reduced crystallinity. These results are consistent with cooling-curve results and SEM images showing structural irregularities. In PCL composites, EA cellulose similarly reduced crystallinity and enthalpy without significantly affecting melting or crystallization temperatures. The decrease in the melting enthalpy from 55.6 J/g to 47.6 J/g suggested the formation of thinner lamellae and less organized crystals, a conclusion supported by stable crystallization temperatures and declining peak intensities in cooling curves. The combination of XRD and DSC data highlighted the dual role of EA cellulose: it enhances nucleation while hindering crystal growth, leading to the formation of more amorphous structures in both PBS and PCL matrices. These findings offer valuable insights into the potential use of EA cellulose as a functional modifier to tailor the properties of biopolymer composites for environmentally friendly, biodegradable applications. Full article

(This article belongs to the Special Issue Adsorption of Pollutants from the Environment Using Polymers and Their Composites)

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37 pages, 9696 KiB

Open AccessReview

Performance and Applications of Polymer Fiber Rubber-Reinforced Concrete in Civil Engineering: A State-of-the-Art Review

by Jie Liu, Wantao Xu, Guansheng Li, Bing Chen, Yi Xiao, Huiping Huang and Juanjuan Chen

Polymers 2025, 17(7), 970; https://doi.org/10.3390/polym17070970 - 2 Apr 2025

Viewed by 431

Abstract

Polymer fiber rubber-reinforced concrete (PFRRC) represents a high-performance composite material that synergistically integrates the energy absorption of rubber concrete (RC) and the crack resistance of polymer fiber-reinforced concrete (PFRC). This review systematically evaluates the mechanical and durability properties of PFRRC, emphasizing its potential [...] Read more.

Polymer fiber rubber-reinforced concrete (PFRRC) represents a high-performance composite material that synergistically integrates the energy absorption of rubber concrete (RC) and the crack resistance of polymer fiber-reinforced concrete (PFRC). This review systematically evaluates the mechanical and durability properties of PFRRC, emphasizing its potential to overcome the intrinsic brittleness of conventional concrete while enhancing structural resilience. Experimental results indicate that PFRRC exhibits significant improvements in compressive, tensile, and flexural strength, with increases of up to 29%, 38%, and 66%, respectively, compared to RC. Furthermore, it demonstrates exceptional impact resistance, with energy absorption capabilities up to 10 times greater than that of ordinary concrete. The hybrid composite also demonstrates enhanced durability, including reduced chloride ion penetration (24.5% lower diffusion coefficient) and improved freeze–thaw resistance. However, challenges remain in optimizing rubber–polymer interactions, fiber hybridization ratios, and performance under extreme conditions. By addressing these limitations, PFRRC holds transformative potential for sustainable infrastructure, particularly in road engineering, seismic-resistant structures, and protective systems. Full article

(This article belongs to the Special Issue Polymer Circularity Towards Carbon Neutrality)

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13 pages, 2153 KiB

Open AccessArticle

Dielectric Tailoring of Perovskite-Polymer Composites for High-Performance Triboelectric Nanogenerators

by Venkatraju Jella, Swathi Ippili and Soon-Gil Yoon

Polymers 2025, 17(7), 969; https://doi.org/10.3390/polym17070969 - 2 Apr 2025

Viewed by 249

Abstract

The rapid advancement of wearable electronics and the Internet of Things (IoT) has driven the demand for sustainable power sources to replace conventional batteries. In this study, we developed a high-performance, lead-free triboelectric nanogenerator (TENG) using methylammonium tin chloride (MASnCl₃) perovskite–poly(methyl [...] Read more.

The rapid advancement of wearable electronics and the Internet of Things (IoT) has driven the demand for sustainable power sources to replace conventional batteries. In this study, we developed a high-performance, lead-free triboelectric nanogenerator (TENG) using methylammonium tin chloride (MASnCl₃) perovskite–poly(methyl methacrylate) (PMMA) composite films. MASnCl₃ was synthesized via an anti-solvent-assisted collision technique and incorporated into a flexible PMMA matrix to enhance dielectric properties, thereby improving triboelectric output. The optimized 10 wt% MASnCl₃–PMMA composite-based TENG exhibited a maximum output voltage of 525 V, a current of 13.6 µA, and of power of 2.5 mW, significantly outperforming the many halide perovskite-based TENGs. The device demonstrated excellent pressure sensitivity, achieving 7.72 V/kPa in voltage detection mode and 0.2 μA/kPa in current detection mode. The device demonstrated excellent mechanical stability and was successfully used to power a small electronic device. The findings highlight the potential of halide perovskite–polymer composites in developing eco-friendly, efficient mechanical energy harvesters for next-generation self-powered electronics and sensor applications. Full article

(This article belongs to the Special Issue Advances in Polymer Composites for Nanogenerator Applications)

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