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Volume 17
Issue 24
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Polymers, Volume 17, Issue 24 (December-2 2025) – 108 articles

Cover Story (view full-size image): The recycling of elastane-containing textiles poses a significant challenge, as even low concentrations of elastane have been observed to disrupt the shredding process and contaminate the recovered fibres. The present work sets out a selective elastane removal process using DMSO–DBN at moderate temperatures, from pure filaments to cotton/polyester fabrics. Elastane is efficiently degraded, while cotton and polyester remain largely intact, thus enabling fibre-to-fibre recycling and supporting more circular pathways for stretch textiles. View this paper
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17 pages, 1798 KB  
Article
Mild Two-Step Thermochemical Recovery of Clean Glass Fibers from Wind-Blade GFRP
by AbdulAziz AlGhamdi, Imtiaz Ali and Salman Raza Naqvi
Polymers 2025, 17(24), 3344; https://doi.org/10.3390/polym17243344 - 18 Dec 2025
Viewed by 472
Abstract
End-of-life wind turbine blade accumulation is a growing global materials management problem and current industrial recycling routes for glass fiber-reinforced polymer composites remain limited in material recovery value. There is limited understanding on how to recover clean glass fibers while keeping thermal exposure [...] Read more.
End-of-life wind turbine blade accumulation is a growing global materials management problem and current industrial recycling routes for glass fiber-reinforced polymer composites remain limited in material recovery value. There is limited understanding on how to recover clean glass fibers while keeping thermal exposure and energy input low, and existing studies have not quantified whether very short isothermal thermal residence can still result in complete matrix removal. The hypothesis of this study is that a mild two-step thermochemical sequence can recover clean glass fibers at lower temperature and near zero isothermal dwell if pyrolysis and oxidation are separated. We used wind-blade epoxy-based GFRP in a step-batch reactor and combined TGA-based thermodynamic mapping, short pyrolysis at 425 °C, and mild oxidation at 475 °C with controlled dwell from zero to thirty minutes. We applied model-free kinetics and machine learning methods to quantify activation energy trends as a function of conversion. The thermal treatment of 425 °C for zero minutes in nitrogen, followed by 475 °C for fifteen minutes in air, resulted in mechanically sound, visually clean white fibers. These fibers retained 76% of the original tensile strength and 88% of the Young’s modulus, which indicates the potential for energy-efficient GFRP recycling. The activation energy was found to be approximately 120 to 180 kJ mol−1. These findings demonstrate energy lean recycling potential for GFRP and can inform future industrial scale thermochemical designs. Full article
(This article belongs to the Special Issue Carbon Fiber Reinforced Polymer Composites: Advancements in Recycling and Sustainability)
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24 pages, 5702 KB  
Article
Preparation and Performance Characterization of Thixotropic Gelling Materials with High Temperature Stability and Wellbore Sealing Properties
by Yingbiao Liu, Xuyang Yao, Chuanming Xi, Kecheng Liu and Tao Ren
Polymers 2025, 17(24), 3343; https://doi.org/10.3390/polym17243343 - 18 Dec 2025
Viewed by 394
Abstract
In response to the requirements of wellbore plugging and lost circulation control, this study designed and prepared a new type of thixotropic polymer gel system. The optimal formula was obtained through systematic screening of the types and concentrations of high molecular polymers, cross-linking [...] Read more.
In response to the requirements of wellbore plugging and lost circulation control, this study designed and prepared a new type of thixotropic polymer gel system. The optimal formula was obtained through systematic screening of the types and concentrations of high molecular polymers, cross-linking agents, flow pattern regulators, and resin curing agents. Comprehensive characterization of the gel’s gelling performance, thixotropic properties, high-temperature stability, shear resistance, and plugging capacity was conducted using methods such as the Sydansk bottle test, rheological testing, high-temperature aging experiments, plugging performance evaluation, as well as infrared spectroscopy, nuclear magnetic resonance, and thermogravimetric analysis, and its mechanism of action was revealed. The results show that the optimal formula is 1.2% AM-AA-AMPS terpolymer + 0.5% hydroquinone + 0.6% S-Trioxane + 0.8% modified montmorillonite + 14% modified phenolic resin. This gel system has a gelling time of 6 h, a gel strength reaching grade H, and a storage modulus of 62 Pa. It exhibits significant shear thinning characteristics in the shear rate range of 0.1~1000 s−1, with a viscosity recovery rate of 97.7% and a thixotropic recovery rate of 90% after shearing. It forms a complete gel at a high temperature of 160 °C, with a dehydration rate of only 8.5% and a storage modulus retention rate of 80% after aging at 140 °C for 7 days. Under water flooding conditions at 120 °C, the converted pressure-bearing capacity per 100 m reaches 24.0 MPa. Mechanism analysis confirms that the system forms a stable composite network through the synergistic effect of “covalent cross-linking—hydrogen bonding—physical adsorption”, providing a high-performance material solution for wellbore plugging in high-temperature and high-salt environments. Full article
(This article belongs to the Topic Polymer Gels for Oil Drilling and Enhanced Recovery)
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12 pages, 2485 KB  
Article
Electrical Modification of Self-Assembled Polymer-Stabilized Periodic Microstructures in a Liquid Crystal Composite
by Miłosz S. Chychłowski, Marta Kajkowska, Jan Bolek, Oleksandra Gridyakina, Bartosz Bartosewicz, Bartłomiej Jankiewicz and Piotr Lesiak
Polymers 2025, 17(24), 3342; https://doi.org/10.3390/polym17243342 - 18 Dec 2025
Viewed by 441
Abstract
Utilization of natural processes can reduce the complexity and production cost of any device by limiting the necessary steps in the production scheme, especially when it comes to fibers with periodic changes in refractive index. One such process is the nematic–isotropic phase separation [...] Read more.
Utilization of natural processes can reduce the complexity and production cost of any device by limiting the necessary steps in the production scheme, especially when it comes to fibers with periodic changes in refractive index. One such process is the nematic–isotropic phase separation of liquid crystal-based composite confined in 1D space. In this paper, we analyze the behavior of polymer-stabilized liquid crystal-based self-assembled periodic structures in an external electric field. We performed a detailed analysis regarding the reorientation of liquid crystal molecules under two orthogonal directions of the external electric field applied to the examined sample. It was demonstrated that the period of the polymerized structure remains constant until full reorientation, as the electric field induces the formation of new periodic defects in LC orientation. Consequently, the structure’s effective birefringence changes quite drastically, and this observed change depends on the direction of the electric field vector. The obtained results seem promising when it comes to application of the proposed periodic structures as voltage or electric field sensors operating as long-period fiber gratings or fiber Bragg gratings for the visible or near-infrared spectral regions. Full article
(This article belongs to the Special Issue Polymer–Liquid Crystal Composites: Their Structure, Function, and Emerging Applications)
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13 pages, 1910 KB  
Article
High-Resolution Photolithographic Patterning of Conjugated Polymers via Reversible Molecular Doping
by Yeongjin Kim, Seongrok Kim, Songyeon Han, Yerin Sung, Yeonhae Ryu, Yuri Kim and Hyun Ho Choi
Polymers 2025, 17(24), 3341; https://doi.org/10.3390/polym17243341 - 18 Dec 2025
Viewed by 580
Abstract
Organic field-effect transistors (OFETs) require reliable micro- and nanoscale patterning of semiconducting layers, yet conjugated polymers have long been considered incompatible with photolithography due to dissolution and chemical damage from photoresist solvents. Here, we present a photolithography-compatible strategy based on doping-induced solubility conversion [...] Read more.
Organic field-effect transistors (OFETs) require reliable micro- and nanoscale patterning of semiconducting layers, yet conjugated polymers have long been considered incompatible with photolithography due to dissolution and chemical damage from photoresist solvents. Here, we present a photolithography-compatible strategy based on doping-induced solubility conversion (DISC), demonstrated using poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT). AuCl3 doping reversibly modulates the benzoid/quinoid resonance balance, lamellar stacking, and π–π interactions, suppressing solubility during lithographic exposure, while dedoping restores the intrinsic electronic properties. Using this approach, micropatterns with linewidths as small as 2 µm were fabricated in diverse geometries—including line arrays, concentric rings, dot arrays, and curved channels—with high fidelity; quantitative analysis of dot arrays yielded mean absolute errors of 48–66 nm and coefficients of variation of 2.0–3.9%, confirming resolution and reproducibility across large areas. Importantly, OFETs based on patterned PBTTT exhibited charge-carrier mobility, threshold voltage, and on/off ratios comparable to spin-coated devices, despite undergoing multiple photolithography steps, indicating preservation of transport characteristics. Furthermore, the same DISC-assisted lithography was successfully applied to other representative p-type conjugated polymers, including P3HT and PDPP-4T, confirming the universality of the method. This scalable strategy thus combines the precision of established lithography with the functional advantages of organic semiconductors, providing a robust platform for high-density organic electronic integration in flexible circuits, biointerfaces, and active-matrix systems. Full article
(This article belongs to the Special Issue Conjugated Polymers: Synthesis, Processing and Applications)
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17 pages, 2104 KB  
Article
Synthesis of Umbelliferone-Based, Thermally Stable, and Intrinsically Flame-Retardant Mono-Oxazine Benzoxazines: Understanding the Aminic Moiety’s Influence on Thermal Properties
by Trey Coughlin, Koki Weng, Maria Laura Salum, Pablo Froimowicz, Chris Scott and Hatsuo Ishida
Polymers 2025, 17(24), 3340; https://doi.org/10.3390/polym17243340 - 18 Dec 2025
Viewed by 432
Abstract
A naturally sourced phenolic compound, umbelliferone, has been used to synthesize four monofunctional benzoxazines, two of which have been previously synthesized from aniline and furfurylamine. This study contributes two more—using benzylamine and phenethylamine—to provide insight into how the amine’s aromatic group and aliphatic [...] Read more.
A naturally sourced phenolic compound, umbelliferone, has been used to synthesize four monofunctional benzoxazines, two of which have been previously synthesized from aniline and furfurylamine. This study contributes two more—using benzylamine and phenethylamine—to provide insight into how the amine’s aromatic group and aliphatic chain length influence resulting properties. The proposed chemical structures of the novel monomers are confirmed by 1H nuclear magnetic resonance (1H-NMR) and 1H-1H nuclear Overhauser effect spectroscopy (NOESY). The polymerization behavior of each resin is determined by differential scanning calorimetry (DSC). The thermal degradation pattern and the flammability of each polymer are assessed by thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC), respectively. Char yields between 49% and 63% suggest the thermoset materials to be thermally stable and competitive for thermally demanding applications. All four polybenzoxazines demonstrate non-ignitable behavior, with heat release capacities below 100 J/g·K. Structure–property analyses on the two newly synthesized compounds have been provided to deepen our existing understanding of umbelliferone-benzoxazine systems, particularly regarding the effect of the aminic moiety on thermal properties. Full article
(This article belongs to the Section Polymer Chemistry)
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24 pages, 16402 KB  
Article
Valorization of Potato Peel Waste into Bioactive Compounds and Sustainable Bioplastics Production Through a Novel Biorefinery Approach
by Rijuta Ganesh Saratale, Ganesh Dattatraya Saratale and Han Seung Shin
Polymers 2025, 17(24), 3339; https://doi.org/10.3390/polym17243339 - 18 Dec 2025
Viewed by 641
Abstract
This study deals with the successful exploitation of easily available and renewable potato peel waste (PPW) as an excellent feedstock in the production of PHA using Ralstonia eutropha. The process entailed the extraction of bioactive components from PPW by use of solvent-based [...] Read more.
This study deals with the successful exploitation of easily available and renewable potato peel waste (PPW) as an excellent feedstock in the production of PHA using Ralstonia eutropha. The process entailed the extraction of bioactive components from PPW by use of solvent-based procedures and screening of their antioxidant and antidiabetic activity. The extracted PPW biomass was subject to acid hydrolysis using different concentrations of sulfuric acid for hydrolysis and solubilization of sugar components. The obtained liquid (acid) hydrolysates were initially assessed to biosynthesize PHA. Activated charcoal-based detoxification of acid hydrolysates was observed to be more efficient in promoting bacterial growth and accumulation of PHA. Acid-pretreated PPW biomass was further enzymatically hydrolysed to accomplish full saccharification and used to produce PHA. The effects of provision of nutrients and employing stress state conditions were assessed to improve bacterial growth and PHA accumulation. In both hydrolysates under optimal conditions, R. eutropha demonstrated the highest biomass productivity of 7.41 g/L and 7.75 g/L, PHA accumulation of 66% and 67% and PHA yield of 4.85 g/L and 5.19 g/L, respectively. XRD, FT-IR, TGA and DSC analysis of produced PHA were studied. The results showed that the produced PHA displayed similar physicochemical and thermal properties to commercially available PHB. Overall, this work illustrates the possibilities of abundantly available PPW, which can be transformed into bioactive compounds and high-value bioplastics via a coupled bioprocess. This approach can develop process economics and sustainability within a cyclic biorefinery system and serve further industry applications. Full article
(This article belongs to the Special Issue Bio-Inspired Polymers: Synthesis, Properties and Applications, 2nd Edition)
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16 pages, 5520 KB  
Article
Enhancing the Mechanical and Rheological Properties of Coal-Based Geopolymer Grouting Materials with Nano-SiO2 and Polypropylene Fibers
by Sai Liu, Lei Zhang, Ning Hou and Wenxuan Meng
Polymers 2025, 17(24), 3338; https://doi.org/10.3390/polym17243338 - 18 Dec 2025
Viewed by 442
Abstract
In order to address the ineffective utilization of industrial solid wastes—particularly fly ash—under the “coal-power integration” model, and to improve the performance of coal-based solid waste geopolymer grouting materials (CBGWG) under dynamic water conditions, this study selected fly ash and coal gangue as [...] Read more.
In order to address the ineffective utilization of industrial solid wastes—particularly fly ash—under the “coal-power integration” model, and to improve the performance of coal-based solid waste geopolymer grouting materials (CBGWG) under dynamic water conditions, this study selected fly ash and coal gangue as the main raw materials to jointly prepare dynamic water grouting slurry. The effects of nano-SiO2 and polypropylene fibers (PPF) on gelation time, initial setting time, bleeding rate, apparent viscosity, compressive strength, and flexural strength were systematically investigated. The experimental results indicate that when the nano-SiO2 content was increased to 1%, the water separation rate decreased by 85.8%, viscosity increased by 17.5%, and both gelation time and initial setting time were reduced by 51.5% and 18.6%, respectively. At a nano-SiO2 content of 0.75% and a PPF dosage of 1.5%, the compressive strength and flexural strength increased by 43.3% and 53%, respectively. However, when the PPF dosage was further increased to 2%, fiber agglomeration occurred during mixing, impairing uniform dispersion. Nano-SiO2 predominantly enhanced the early stiffness of the consolidated body, while PPF significantly improved ductility, residual load-bearing capacity, and energy dissipation, albeit at the expense of some stiffness. These two modifiers exhibited complementary effects in improving the mechanical properties of the grouting material. The optimal dosages of nano-SiO2 and PPF were determined to be 0.75% and 1.5%, respectively, achieving the best balance between mechanical properties and workability. Full article
(This article belongs to the Section Polymer Applications)
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15 pages, 3425 KB  
Article
Nanoindentation Analysis of SU-8 Coated Wafers at Different Baking Phases
by Tamás Tarjányi, Gábor Gulyás, Krisztián Bali, Márton Sámi, Rebeka Anna Kiss, Barbara Beiler, Péter Fürjes and Tibor Szabó
Polymers 2025, 17(24), 3337; https://doi.org/10.3390/polym17243337 - 18 Dec 2025
Viewed by 479
Abstract
SU-8 photoresist is extensively used as a structural and passivation layer in microelectromechanical systems, microfluidic devices, and related microscale technologies. The long-term reliability of these devices critically depends on the mechanical integrity and viscoelastic behaviour of the SU-8 coating. In this study, the [...] Read more.
SU-8 photoresist is extensively used as a structural and passivation layer in microelectromechanical systems, microfluidic devices, and related microscale technologies. The long-term reliability of these devices critically depends on the mechanical integrity and viscoelastic behaviour of the SU-8 coating. In this study, the mechanical and viscoelastic behaviour of SU-8 polymer thin films was systematically investigated using nanoindentation at different baking stages representative of standard photolithographic processing. SU-8 layers were spin-coated on silicon wafers and subjected to pre-bake, post-bake, and hard-bake treatments to evaluate the effects of progressive cross-linking. Static nanoindentation revealed that the elastic modulus did not change significantly during the baking phases and remained near 6.2 GPa; however, a significant change in hardness was observed from 0.173 ± 0.012 GPa after pre-bake to 0.365 ± 0.011 GPa and 0.364 ± 0.016 GPa after post- and hard bake, respectively. Creep tests analysed by the Burgers viscoelastic model showed a significant increase in both the retarded modulus and viscosity parameters with thermal curing, indicating the suppression of long-term viscoelastic deformation. The combined results demonstrate that nanoindentation provides a sensitive, nondestructive tool for monitoring the evolution of cross-linking and viscoelastic stability in SU-8 films, offering valuable insight for process optimization and mechanical reliability in MEMS and microfluidic applications. Full article
(This article belongs to the Special Issue Silicon-Based Polymers: From Synthesis to Applications)
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12 pages, 3755 KB  
Article
Impact of Design Variations and Infill Density in 3D-Printed PLA Components
by Pradeep Raja, Karthik Babu, Elif Kaynak and Oisik Das
Polymers 2025, 17(24), 3336; https://doi.org/10.3390/polym17243336 - 18 Dec 2025
Viewed by 542
Abstract
3D printing offers the ability to fabricate lightweight structural profiles with controlled infill and geometry. This study examines the mechanical behaviour of 3D-printed polylactic acid (PLA) structures with a 10% infill density under four load conditions (10, 15, 20, and 25 N). Four [...] Read more.
3D printing offers the ability to fabricate lightweight structural profiles with controlled infill and geometry. This study examines the mechanical behaviour of 3D-printed polylactic acid (PLA) structures with a 10% infill density under four load conditions (10, 15, 20, and 25 N). Four designs (M1, M2, M3, and M4), representing commonly used structural profiles found in beam and column applications, were analysed using ANSYS finite element simulations. Each design was evaluated under roller and nodal boundary conditions to study deformation, stress, and strain responses. Three-point flexural tests were also carried out on all four designs, and the measured peak flexural stress and apparent flexural modulus were compared with the simulated stiffness values. Both the simulations and experimental results showed that Design M3 exhibited the highest stiffness and more consistent behaviour compared to the other designs, while Design M4 showed higher deformation and lower bending resistance. Roller supports generally reduced deformation through better load distribution, whereas nodal supports increased local stiffness in selected designs. Although the magnitude of stiffness differed between simulation and experiment, the ranking of the designs remained consistent. Overall, the study confirms that the geometry plays an important role in their load-bearing performance, and the numerical model provides a reliable tool for comparing and selecting suitable designs before fabrication. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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25 pages, 5342 KB  
Article
Evaluation of Jute–Glass Ratio Effects on the Mechanical, Thermal, and Morphological Properties of PP Hybrid Composites for Sustainable Automotive Applications
by Tunahan Özyer and Emre Demirci
Polymers 2025, 17(24), 3335; https://doi.org/10.3390/polym17243335 - 17 Dec 2025
Viewed by 451
Abstract
This study investigates polypropylene (PP)–based biocomposites reinforced with systematically varied jute and glass fiber ratios as sustainable, lightweight alternatives for semi-structural automotive parts. Four formulations (J20/G0, J15/G5, J10/G10, J5/G15) with a constant 20 wt% total fiber were produced by injection molding and characterized [...] Read more.
This study investigates polypropylene (PP)–based biocomposites reinforced with systematically varied jute and glass fiber ratios as sustainable, lightweight alternatives for semi-structural automotive parts. Four formulations (J20/G0, J15/G5, J10/G10, J5/G15) with a constant 20 wt% total fiber were produced by injection molding and characterized through mechanical, thermal, and morphological analyses. Tensile, flexural, and Charpy impact tests showed progressive improvements in strength, stiffness, and energy absorption with increasing glass fiber content, while ductility was maintained or slightly enhanced. SEM revealed a transition from fiber pull-out in jute-rich systems to fiber rupture and stronger matrix adhesion in glass-rich hybrids. Thermal analyses confirmed the benefits of hybridization: heat deflection temperature increased from 75 °C (J20/G0) to 103 °C (J5/G15), and thermogravimetry indicated improved stability and higher char residue. DSC showed negligible changes in crystallization and melting, confirming that fiber partitioning does not significantly affect PP crystallinity. Benchmarking demonstrated mechanical and thermal performance comparable to acrylonitrile–butadiene–styrene (ABS) and acrylonitrile–styrene–acrylate (ASA), widely used in automotive components. Finally, successful molding of a prototype exterior mirror cap from J20/G0 validated industrial processability. These findings highlight jute–glass hybrid PP composites as promising, sustainable alternatives to conventional engineering plastics for automotive engineering applications. Full article
(This article belongs to the Special Issue Advances in Composite Materials: Polymers and Fibers Inclusion)
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23 pages, 3324 KB  
Article
Residual Utilization of Crab Solid Parts for Powder Production and Application as a Structural Component in the Polymeric Matrix of Biodegradable Films
by Fábio G. Teles, Railene H. C. R. Araújo, Aline D. B. Arriel, Valdilene M. C. Soares, Adriano S. Silva, Kalinny A. Alves, Maria A. S. Morais, Patrícia L. D. Morais, Nayara S. Rocha, Antonio G. B. Lima and João M. P. Q. Delgado
Polymers 2025, 17(24), 3334; https://doi.org/10.3390/polym17243334 - 17 Dec 2025
Viewed by 408
Abstract
Natural fillers have been widely explored to enhance the mechanical and barrier properties of biodegradable films. In this study, a mineral-rich powder obtained from the solid components of Ucides cordatus crab shells was processed (washing, drying, milling, and sieving at 75 µm) and [...] Read more.
Natural fillers have been widely explored to enhance the mechanical and barrier properties of biodegradable films. In this study, a mineral-rich powder obtained from the solid components of Ucides cordatus crab shells was processed (washing, drying, milling, and sieving at 75 µm) and extensively characterized using SEM, FTIR XRD, EDX, mineral analysis, hygroscopicity, density, and particle size distribution. The powder exhibited heterogeneous morphology and contained 22.52 g·kg−1 of calcium carbonate, along with other trace minerals; its crystalline profile indicated the presence of both calcite and aragonite. Low hygroscopicity (1.76%) and a true density of 2.11 g/cm3 were also observed. When incorporated into pectin-based films at 1–5%, the filler promoted a reduction in film thickness, indicating enhanced structural compaction. Solubility increased linearly with filler content, whereas water vapor permeability (WVP) decreased at 1% and 2% but rose again at 4% and 5%, correlating positively with solubility (r = 0.895). Films containing 4% and 5% exhibited higher tensile strength and elastic modulus, confirming increased rigidity. At elevated concentrations, the films also became less luminous and more chromatic. Overall, the findings demonstrate that crab-shell mineral powder is a viable and sustainable reinforcement capable of tailoring the structural, mechanical, and barrier performance of biodegradable films. Full article
(This article belongs to the Special Issue Advances in Polymers: From Fabrication Technologies to Applications in Biotechnology and Biomedicine)
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19 pages, 2381 KB  
Article
Low-Temperature Performance and Tribological Properties of Poly(5-n-butyl-2-norbornene) Lubricating Oils: Effect of Molecular Weight and Hydrogenation on the Viscosity and Anti-Wear Activity
by Valeriia R. Nazemutdinova, Sergey O. Ilyin, Aleksandr A. Morontsev, Igor S. Makarov, Alyona I. Wozniak and Maxim V. Bermeshev
Polymers 2025, 17(24), 3333; https://doi.org/10.3390/polym17243333 - 17 Dec 2025
Viewed by 509
Abstract
A series of poly(5-n-butyl-2-norbornene) oils with controlled molecular weights was synthesized via metathesis polymerization, fully hydrogenated, and characterized in terms of viscosity and tribological performance. In contrast to established lubricant base stocks—such as poly(α-olefins) and multiply alkylated cyclopentanes—these novel norbornene-based polymers [...] Read more.
A series of poly(5-n-butyl-2-norbornene) oils with controlled molecular weights was synthesized via metathesis polymerization, fully hydrogenated, and characterized in terms of viscosity and tribological performance. In contrast to established lubricant base stocks—such as poly(α-olefins) and multiply alkylated cyclopentanes—these novel norbornene-based polymers remain underexplored, despite their promising anti-wear activity. Based on differential scanning calorimetry (DSC) data, all the synthesized products are amorphous compounds whose thermograms show a single glass transition temperature. The effect of molecular weight and temperature on the viscosity of poly(5-n-butyl-2-norbornene) oils was quantified over an extended temperature range, including extra-cold conditions down to −80 °C. The pour points of the oils were determined and can be as low as −66 °C, indicating excellent low-temperature fluidity. The tribological performance of the synthesized oils was evaluated using the four-ball test, with friction coefficient and wear scar diameter measured to assess anti-wear and antifriction properties. The tribological results were benchmarked against commercially available polyalphaolefin (PAO) oils (PAO-4, PAO-20, and PAO-80). Metathesis and hydrogenated poly(5-n-butyl-2-norbornene) oils outperform conventional PAOs by up to 67% in wear protection and 30% in friction reduction. These findings establish alicyclic molecular strain as a viable design parameter for next-generation lubricating oils, thereby expanding the toolbox for material development beyond conventional chemical functionalization. Full article
(This article belongs to the Section Polymer Applications)
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21 pages, 2502 KB  
Article
Impact of EVOH, Ormocer® Coating, and Printed Labels on the Recyclability of Polypropylene for Packaging Applications
by Romana Schmiedt, Michael Krainz, Katharina Tosic, Farshad Sharbafian, Simon Krauter, Victoria Krauter, Martin Novak, Bernhard Rainer, Michael Washüttl and Silvia Apprich
Polymers 2025, 17(24), 3332; https://doi.org/10.3390/polym17243332 - 17 Dec 2025
Viewed by 522
Abstract
Flexible packaging often consists of multilayer films that combine different materials to achieve high barrier performance, but these structures are incompatible with current recycling technologies. Polyolefins such as polypropylene (PP) offer more recyclable alternatives but require additional oxygen-barrier materials that do not compromise [...] Read more.
Flexible packaging often consists of multilayer films that combine different materials to achieve high barrier performance, but these structures are incompatible with current recycling technologies. Polyolefins such as polypropylene (PP) offer more recyclable alternatives but require additional oxygen-barrier materials that do not compromise recyclability. This study investigates the influence of ethylene vinyl alcohol (EVOH), Ormocer® barrier coating, and PP labels with different adhesives on PP recyclability. Recyclates were produced using twin-screw extruder to simulate the recycling process and then injection-molding to make tensile test specimens. Mechanical properties, melt flow rate (MFR), oxygen induction time (OIT), and odor were evaluated. Findings showed that low label content (5–12.5%) has minimal impact on recyclate quality. The addition of 10% EVOH increased the elastic modulus of PP granulate and cast-PP (cPP) film by 26% and 14%, respectively, and improved oxidation stability by 9%, while reducing cPP film impact strength by 77%. Ormocer® decreased mechanical performance, particularly elongation at break (−18%), likely due to defect-inducing particles, but had limited influence on MFR. Labels and Ormocer® also introduced odor variations. Overall, the findings indicate that EVOH up to 10% and labels up to 12.5% yield promising results, providing guidance for designing recyclable, monomaterial packaging. Full article
(This article belongs to the Section Circular and Green Sustainable Polymer Science)
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30 pages, 3933 KB  
Review
Next-Generation Electrically Conductive Polymers: Innovations in Solar and Electrochemical Energy Devices
by Thirukumaran Periyasamy, Shakila Parveen Asrafali and Jaewoong Lee
Polymers 2025, 17(24), 3331; https://doi.org/10.3390/polym17243331 - 17 Dec 2025
Viewed by 727
Abstract
The emergence of electrically conductive polymeric materials has revolutionized the landscape of sustainable energy technologies, presenting unprecedented opportunities for advancing both photovoltaic conversion systems and electrochemical energy-storage platforms. These remarkable macromolecular materials exhibit distinctive characteristics including adjustable electronic band structures, exceptional mechanical adaptability, [...] Read more.
The emergence of electrically conductive polymeric materials has revolutionized the landscape of sustainable energy technologies, presenting unprecedented opportunities for advancing both photovoltaic conversion systems and electrochemical energy-storage platforms. These remarkable macromolecular materials exhibit distinctive characteristics including adjustable electronic band structures, exceptional mechanical adaptability, solution-phase processability, and cost-effective manufacturing potential. This extensive review provides an in-depth examination of the fundamental principles governing charge carrier mobility in conjugated polymer systems, explores diverse synthetic methodologies for tailoring molecular architectures, and analyzes their transformative applications across multiple energy technology domains. In photovoltaic technologies, electrically conductive polymers have driven major advancements in organic solar cells and photoelectrochemical systems, significantly improving energy conversion efficiency while reducing manufacturing costs. In electrochemical energy storage, their integration into supercapacitors and rechargeable lithium-based batteries has enhanced charge storage capability, accelerated charge–discharge processes, and extended operational lifespan compared with conventional electrode materials. This comprehensive analysis emphasizes emerging developments in hybrid composite architectures that combine conductive polymers with carbon-based nanomaterials, metal oxides, and other functional components to create next-generation flexible, lightweight, and wearable energy systems. By synthesizing fundamental materials chemistry with device engineering perspectives, this review illuminates the transformative potential of electrically conductive polymers in establishing sustainable, efficient, and resilient energy infrastructures for future technological landscapes. Full article
(This article belongs to the Special Issue Application and Development of Polymeric Materials in Electrochemistry)
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42 pages, 26296 KB  
Article
Gamma Radiation Shielding Efficiency of Cross-Linked Polystyrene-b-Polyethyleneglycol Block Copolymer Nanocomposites Doped Arsenic (III) Oxide and Boron Nitride Nanoparticles
by Bülend Ortaç, Taylan Baskan, Saliha Mutlu, Sevil Savaskan Yilmaz and Ahmet Hakan Yilmaz
Polymers 2025, 17(24), 3330; https://doi.org/10.3390/polym17243330 - 17 Dec 2025
Viewed by 403
Abstract
In recent years, polymer-based hybrid nanocomposites have emerged as promising alternatives to traditional heavy metal shields due to their low density, flexibility, and environmental safety. In this study, the synthesis of PS-PEG copolymers and the gamma radiation-shielding properties of PS-PEG/As2O3 [...] Read more.
In recent years, polymer-based hybrid nanocomposites have emerged as promising alternatives to traditional heavy metal shields due to their low density, flexibility, and environmental safety. In this study, the synthesis of PS-PEG copolymers and the gamma radiation-shielding properties of PS-PEG/As2O3, PS-PEG/BN, and PS-PEG/As2O3/BN nanocomposites with different compositions are investigated. The goal is to find the optimal nanocomposite composition for gamma radiation shielding and dosimetry. Therefore, the mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), tenth-value layer (TVL), effective atomic number, mean free path (MFP), radiation shielding efficiency (RPE), electron density, and specific gamma-ray constant were presented. Gamma rays emitted by the Eu source were detected by a high-purity germanium (HPGe) detector device. GammaVision was used to analyze the given data. Photon energy was in the vicinity of 121.8–1408.0 keV. The MAC values in XCOM simulation tools were used to compute. Gamma-shielding efficiency was increased by an increased number of NPs at a smaller photon energy. At 121.8 keV, the HVL of a composite with 70 wt% As2O3 NPs is 2.00 cm, which is comparable to the HVL of lead (0.56 cm) at the same energy level. Due to the increasing need for lightweight, flexible, and lead-free shielding materials, PS-b-PEG copolymer-based nanocomposites reinforced with arsenic oxide and BN NPs will be materials of significant interest for next-generation radiation protection applications. Full article
(This article belongs to the Special Issue Recent Advances and Applications of Polymer Nanocomposites)
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57 pages, 2797 KB  
Review
Active Packaging Based on Chitosan, Fish Gelatin, Zein, and Kafirin Biopolymers: A Promising Strategy for Innovation in the Cosmetic Sector
by Andres C. Arana-Linares, Alvaro Barrera-Ocampo, Arley Camilo Patiño, Yhors Ciro and Constain H. Salamanca
Polymers 2025, 17(24), 3329; https://doi.org/10.3390/polym17243329 - 17 Dec 2025
Viewed by 696
Abstract
Background: Biopolymer-based active packaging has experienced significant growth in the food industry due to its capacity to enhance product stability and reduce reliance on synthetic preservatives. However, its application in cosmetics remains limited, despite increasing consumer demand for sustainable and preservative-free solutions. Objective: [...] Read more.
Background: Biopolymer-based active packaging has experienced significant growth in the food industry due to its capacity to enhance product stability and reduce reliance on synthetic preservatives. However, its application in cosmetics remains limited, despite increasing consumer demand for sustainable and preservative-free solutions. Objective: This review evaluates the feasibility of transferring biopolymer-based active packaging technologies from the food sector to cosmetic applications, identifying relevant materials, processing methods, and implementation challenges. Methodology: A bibliographic search was conducted across nine databases (2000–2025) using the keywords “active packaging,” “antioxidant,” “antimicrobial,” and “biopolymers.” Results: The most recurrent biopolymers identified were chitosan, fish gelatin, zein, and kafirin, all of which exhibit biodegradability, film-forming capacity, and compatibility with natural additives. Although their intrinsic antioxidant and antimicrobial properties are limited, these can be enhanced through the incorporation of bioactive compounds. Processing techniques such as casting, coating, dry forming, and electrospinning were found to be the most effective, enabling customized packaging designs. Key challenges include cost, sensory attributes, mechanical limitations, and regulatory compliance. Conclusion: Active packaging systems based on biopolymers—either alone or combined with natural bioactive ingredients—offer a viable innovation pathway for the cosmetics industry. These systems support clean-label claims and ecological positioning, representing a strategic opportunity to adapt validated technologies from the food sector to meet emerging cosmetic market demands. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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23 pages, 5287 KB  
Article
Development and Characterization of Biodegradable Polymer Filaments for Additive Manufacturing
by Tomáš Balint, Jozef Živčák, Radovan Hudák, Marek Schnitzer, Miroslav Kohan, Maria Danko, Richard Staško, Peter Szedlák, Marek Jałbrzykowski, Katarzyna Leszczyńska, Pavol Alexy, Ivana Bírová, Zuzana Vanovčanová and Martina Culenová
Polymers 2025, 17(24), 3328; https://doi.org/10.3390/polym17243328 - 17 Dec 2025
Viewed by 577
Abstract
In this study, the authors focus on optimizing the processing parameters for the fabrication of biodegradable polymer filaments intended for subsequent 3D printing of biomedical structures and implants. Following extrusion and additive manufacturing, the produced materials underwent a comprehensive evaluation that included mechanical, [...] Read more.
In this study, the authors focus on optimizing the processing parameters for the fabrication of biodegradable polymer filaments intended for subsequent 3D printing of biomedical structures and implants. Following extrusion and additive manufacturing, the produced materials underwent a comprehensive evaluation that included mechanical, microbiological, biofilm formation, and electron microscopy analyses. The complexity of these tests aimed to determine the potential of the developed materials for biomedical applications, particularly in the field of scaffold fabrication. At the initial stage, three types of filaments (technical designations 111, 145, and 146) were produced using Fused Filament Fabrication (FFF) technology. These filaments were based on a PLA/PHB matrix with varying types and concentrations of plasticizers. Standardized destructive tensile and compressive mechanical tests were conducted using an MTS Insight 1 kN testing system equipped with an Instron 2620-601 extensometer. Among the tested samples, the filament labeled 111, composed of PLA/PHB thermoplastic starch and a plasticizer, exhibited the most favorable mechanical performance, with a Young’s modulus of elasticity of 4.63 MPa for 100% infill. The filament labeled 146 had a Young’s modulus of elasticity of 4.53 MPa for 100% infill and the material labeled 145 had a Young’s modulus of elasticity of 1.45 MPa for 100% infill. Microbiological assessments were performed to evaluate the capacity of bacteria and fungi to colonize the material surfaces. During bacterial activity assessment, we observed biofilm formation on the examined sample surfaces of each material from the smooth and rough sides. The colony-forming units (CFUs) increased directly with the exposure time. For all samples from each material, the Log10 (CFU) value reached above 9.41 during 72 h of incubation for the activity of each type of bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans). Scanning electron microscopy provided insight into the surface quality of the material and revealed its local quality and purity. Surface defects were eliminated by this method. Overall, the results indicate that the designed biodegradable filaments, especially formulation 111, have promising properties for the development of scaffolds intended for hard tissue replacement and could also be suitable for regenerative applications in the future after achieving the desired biological properties. Full article
(This article belongs to the Special Issue 3D Printing of Polymer Composite Materials—Advances in Materials and Processes)
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23 pages, 8590 KB  
Article
The Effect of Pattern Addition on the Mechanical Properties of 3D-Printed Parts
by Nergizhan Anaç and Oğuz Koçar
Polymers 2025, 17(24), 3327; https://doi.org/10.3390/polym17243327 - 17 Dec 2025
Viewed by 507
Abstract
Additive manufacturing is a suitable method for multi-material production, as it offers flexibility in structural design and enables layer-by-layer fabrication of materials. However, the different chemical structures and formulations of the materials used may affect the mechanical integrity of the part. In nature, [...] Read more.
Additive manufacturing is a suitable method for multi-material production, as it offers flexibility in structural design and enables layer-by-layer fabrication of materials. However, the different chemical structures and formulations of the materials used may affect the mechanical integrity of the part. In nature, there are many patterned structures that inspire the design of multi-material additive manufacturing components. Integrating the harmony and advantages of these natural structures into the manufacturing process will significantly contribute to human development. This study presents a novel manufacturing approach for using existing natural or artificially produced pattern forms in the development of composite materials. In this aim, patterned parts composed of multiple materials were produced using a 3D printer with combinations of PLA Plus, PLA CF, and PLA GF. Mechanical tests were conducted on the produced parts, and their fracture surfaces were examined. In patterned specimens, tensile strength decreased compared to reference (non-patterned) specimens. In the PLA Plus–PLA Plus and PLA Plus–PLA CF combinations, tensile strength generally decreased in samples with three patterns, while the greatest reduction in tensile strength occurred in the PLA Plus–PLA GF patterned specimens. The highest bending forces were obtained in single- and five-pattern samples with PLA Plus–PLA Plus and PLA Plus–PLA CF combinations, as well as in five-pattern samples with the PLA Plus–PLA GF combination. The results indicate that the presence and number of patterns are important factors influencing the mechanical properties of the specimens. Full article
(This article belongs to the Special Issue Research Progress on Mechanical Behavior of Polymers, 2nd Edition)
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13 pages, 852 KB  
Article
Relaxation Processes of Food Hydrocolloids in Diluted, Semidilute, and Concentrated Solutions: NMR and Hydrodynamic Approach
by Magdalena Witek, Anna Ptaszek and Paweł Ptaszek
Polymers 2025, 17(24), 3326; https://doi.org/10.3390/polym17243326 - 17 Dec 2025
Viewed by 375
Abstract
The paper presents the results of relaxation studies for aqueous solutions of guar gum (GG) and xanthan gum (XG) in diluted, semidilute, and concentrated ranges over a wide temperature range (20–90 °C). Relaxation studies were performed using NMR and DLS methods. Due to [...] Read more.
The paper presents the results of relaxation studies for aqueous solutions of guar gum (GG) and xanthan gum (XG) in diluted, semidilute, and concentrated ranges over a wide temperature range (20–90 °C). Relaxation studies were performed using NMR and DLS methods. Due to variations in the biopolymer–biopolymer interactions, XG chains formed a more complex structure in solution than GG chains did. Consequently, differences in T2 relaxation times were observed in the diluted and semidilute regions. Comparing the autocorrelation functions of XG and GG solutions in the semidilute region revealed differences in their relaxation behaviour. Full article
(This article belongs to the Special Issue Natural Polymers and Composites for Food Applications)
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15 pages, 1016 KB  
Article
Effect of bis-TEMPO Sebacate on Mechanical Properties and Oxidative Resistance of Peroxide-Crosslinked Polyolefin Compositions
by Artem Chizhov, Aleksandr Goriaev, Svetlana Belus and Maksim Svistunov
Polymers 2025, 17(24), 3325; https://doi.org/10.3390/polym17243325 - 17 Dec 2025
Viewed by 418
Abstract
TEMPO derivatives are well known as scorch retardants due to their ability to effectively quench free alkyl radicals during peroxide crosslinking of polymer compositions. However, in practice this leads to the loss of crosslinking density due to a irreversible decrease in the number [...] Read more.
TEMPO derivatives are well known as scorch retardants due to their ability to effectively quench free alkyl radicals during peroxide crosslinking of polymer compositions. However, in practice this leads to the loss of crosslinking density due to a irreversible decrease in the number of alkyl radicals involved in the crosslinking process. One approach to solving this problem is the use of TEMPO-based biradical molecules, which, on the one hand, are able to effectively quench alkyl radicals, and on the other hand, can couple macroradicals, partially compensating for the loss of crosslinking density. The aim of this work was to reveal the effect of bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate (bis-TEMPO) in the concentration range of 0.11–0.44 phr on the delay in the onset of dynamic crosslinking of polyolefin composites initiated by peroxide, as well as the oxidative stability of the resulting crosslinked composites. The obtained data show that using bis-TEMPO at a concentration of less than 0.27 phr increases the crosslinking density of the polyolefin composite, with a crosslinking onset delay of up to 36 s achieved. Simultaneously, antioxidant functionality of bis-TEMPO in crosslinked composites is considered moderate and leads to an increase in the OIT values by 1.7–2.8 times. The crosslinking onset delay time under dynamic conditions is well described by a first-order kinetic model at a constant temperature. The obtained data confirm the efficiency and predictability of bis-TEMPO as a scorch retardant for polyolefin composites. Full article
(This article belongs to the Special Issue Sustainable Polymer Materials for Industrial Applications)
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15 pages, 5811 KB  
Article
Tailoring Functionalized Lignin-Based Spherical Resins as Recyclable Adsorbents for Heavy Metal Uptake
by Gao Xiao, Shumin Xie, Bizheng Mao, Hong Chen, Yiwei Xue, Qingmei Xu, Jie Guo and Manna Dai
Polymers 2025, 17(24), 3324; https://doi.org/10.3390/polym17243324 - 16 Dec 2025
Viewed by 351
Abstract
A novel mesoporous spherical chelating lignin-based adsorbent was successfully synthesized via inverse suspension polymerization using sulfate pine pulping black liquor as raw material, followed by graft copolymerization with acrylonitrile and subsequent amination. The obtained aminated cyanoethyl spherical lignin resin (ACSLR) exhibited a well-defined [...] Read more.
A novel mesoporous spherical chelating lignin-based adsorbent was successfully synthesized via inverse suspension polymerization using sulfate pine pulping black liquor as raw material, followed by graft copolymerization with acrylonitrile and subsequent amination. The obtained aminated cyanoethyl spherical lignin resin (ACSLR) exhibited a well-defined porous morphology and abundant active sites, as confirmed by SEM and FT-IR. Adsorption experiments demonstrated high Pb2+ uptake capacity (63.98 mg·g−1) under optimal conditions (pH = 5.5, 2.0 g·L−1 adsorbent dosage, and 150 mg·L−1 initial concentration of Pb2+ solution). The adsorption process followed the Langmuir isotherm and pseudo-second-order kinetics, indicating monolayer chemisorption dominated by amino and cyano groups. This work provides a sustainable strategy for valorizing industrial lignin waste into efficient adsorbents for heavy metal removal, highlighting its potential for practical wastewater treatment applications. Full article
(This article belongs to the Section Circular and Green Sustainable Polymer Science)
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15 pages, 2603 KB  
Article
Room-Temperature Synthesis of Pullulan-Based Hydrogels for Controlled Delivery of Microbial Fertilizers
by Tamara Erceg, Ivana Mitrović, Vesna Teofilović, Darko Micić and Sanja Ostojić
Polymers 2025, 17(24), 3323; https://doi.org/10.3390/polym17243323 - 16 Dec 2025
Viewed by 416
Abstract
This study presents an energy-efficient, room-temperature synthesis and characterization of methacrylated pullulan (Pull-MA) hydrogel developed for controlled nutrient delivery in agricultural applications. Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) analyses confirmed the successful functionalization of pullulan with methacrylate groups, accompanied [...] Read more.
This study presents an energy-efficient, room-temperature synthesis and characterization of methacrylated pullulan (Pull-MA) hydrogel developed for controlled nutrient delivery in agricultural applications. Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) analyses confirmed the successful functionalization of pullulan with methacrylate groups, accompanied by a decrease in thermal transition temperatures, indicative of increased polymer chain mobility. The synthesized Pull-MA hydrogel exhibited a high swelling capacity, reaching an equilibrium swelling ratio of 1068% within 5 h, demonstrating its suitability as a carrier matrix. The room-temperature synthesis approach enabled the in situ incorporation of microbial inoculant into the hydrogel network, preserving microbial viability and activity. SEM analysis performed under the different magnifications (1000, 2500, 5000, 10,000, 25,000×) has confirmed brittle nature of xerogels and increasing in structural irregularities with increasing in cultivation broth content.The biological performance of the fertilizer-loaded hydrogels was evaluated through seed germination assays using maize and pepper as model crops. The optimized formulation, T2 (Pull-MA: cultivation broth 1:5 w/w), significantly improved germination efficiency, as evidenced by increased relative seed germination (RSG), root growth rate (RRG), and germination index (GI) compared to both the control and the low-fertilizer formulation (T1, 1:2.5 w/w). These findings highlight the potential of Pull-MA hydrogels as bioactive seed-coating materials that enhance early seedling development through controlled nutrient release. The results lay a solid foundation for further optimization and future application of this system under real field conditions. Full article
(This article belongs to the Special Issue Polymer Hydrogels: Synthesis, Properties and Applications)
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24 pages, 4641 KB  
Article
The Impact of Pressure-Dependent Viscosity Data on Injection Molding Simulations of Highly Filled Thermoplastics
by Felix Kerling, Samuel Schlicht, Benedikt Roth, Tobias Kleffel, Uta Rösel and Dietmar Drummer
Polymers 2025, 17(24), 3322; https://doi.org/10.3390/polym17243322 - 16 Dec 2025
Cited by 1 | Viewed by 443
Abstract
The injection compression molding using dynamic mold control (ICM-DT) represents a promising technological approach to the manufacturing of highly filled, modified thermoplastic components with tight geometric tolerances. While the numerical prediction of flow states is, to date, predominantly based on the Cross–WLF modeling [...] Read more.
The injection compression molding using dynamic mold control (ICM-DT) represents a promising technological approach to the manufacturing of highly filled, modified thermoplastic components with tight geometric tolerances. While the numerical prediction of flow states is, to date, predominantly based on the Cross–WLF modeling of viscoelastic characteristics of the melt, new material-related developments necessitate the assessment of process- and material-related boundaries. The present paper employs a highly filled graphite–polypropylene system, exhibiting a graphite mass fraction of 80%, for the quantitative comparison of Cross–WLF predictions and experimentally derived flow states. Based on coupled counter pressure-chamber high-pressure capillary rheometry (CPC-HCR) and counterpressurized viscometry (CPV) alongside the ICM-DT of thin-walled specimens, pressure-induced crystallization was identified to induce significant deviations from Cross–WLF predictions. Cross–WLF modeling strongly overestimates the processability of the applied graphite–polypropylene system under both injection molding (IM) and ICM regimes. We therefore observe a predominant influence of pressure-induced crystallization mechanisms in dynamic mold temperature process domains, in which the pressure-induced, crystallization-related exponential viscosity increase cannot be adequately modeled through both pressure-dependent and pressure-agnostic Cross–WLF models. The numerical approximation of flow states under dynamic mold temperature regimes hence necessitates the consideration of solidification-induced, self-intensifying pressure excursions. Full article
(This article belongs to the Special Issue Injection Molding and Special Injection Molding Technologies of Polymer and Polymer Composites)
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15 pages, 2119 KB  
Article
Lightweight Modification of Polypropylene Cable Insulation Materials Doped with Hollow Glass Microspheres
by Xindong Zhao, Dongxu Luo, Kai Wang, Jiaming Yang, Ling Weng, Xiongjun Liu, Xiao Han and Xin Yao
Polymers 2025, 17(24), 3321; https://doi.org/10.3390/polym17243321 - 16 Dec 2025
Viewed by 446
Abstract
Overhead transmission lines have long relied on cross-linked polyethylene (XLPE) insulation. The production of XLPE insulation requires silane cross-linking, which generates by-products, consumes high energy, and results in poor recyclability-retired XLPE insulation can only be disposed of through incineration or landfilling. Additionally, its [...] Read more.
Overhead transmission lines have long relied on cross-linked polyethylene (XLPE) insulation. The production of XLPE insulation requires silane cross-linking, which generates by-products, consumes high energy, and results in poor recyclability-retired XLPE insulation can only be disposed of through incineration or landfilling. Additionally, its high density leads to increased cable weight and sag, reducing the service life of the cables. Therefore, there is an urgent need to develop recyclable and lightweight insulation materials. In this study, recyclable polypropylene (PP) was used as a substitute for XLPE. Hollow glass microspheres (HGM) were incorporated to reduce weight, and hydrogenated styrene-ethylene-butylene-styrene block copolymer (SEBS) was added for toughening, thereby constructing a PP/HGM/SEBS ternary composite system. The results show that the introduction of HGM into the PP matrix effectively reduces the material density, decreasing from 0.890 g/cm3 (pure PP) to 0.757 g/cm3—a reduction of 15%. With the addition of SEBS, the mechanical properties of the composite are significantly improved: the tensile strength increases from 14.94 MPa (PP/HGM) to 32.40 MPa, and the elongation at break jumps sharply from 72.02% to 671.22%, achieving the synergistic optimization of “weight reduction” and “strengthening-toughening”. Electrical performance tests indicate that the PP/HGM/SEBS composite exhibits a volume resistivity of 1.66 × 1012 Ω·m, a characteristic breakdown strength of 108.6 kV/mm, a low dielectric loss tangent of 2.76 × 10−4, and a dielectric constant of 2.24. It achieves density reduction while maintaining low dielectric loss and high insulation strength, verifying its feasibility for application in lightweight insulation scenarios of overhead transmission lines. Full article
(This article belongs to the Special Issue High-Performance Thermoplastic Polymer Composites: From Fabrication to Application)
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7 pages, 791 KB  
Communication
Influence of Nozzle Speed on the Crystallinity and Solubility of Polyvinyl Alcohol in Material Extrusion
by Ji Eun Lee, Yong Son and Seong Je Park
Polymers 2025, 17(24), 3320; https://doi.org/10.3390/polym17243320 - 16 Dec 2025
Viewed by 335
Abstract
Material extrusion (MEX) commonly requires support structures, and their rapid removal is essential for improving overall process efficiency. This study investigates the effect of nozzle speed on the crystallinity and dissolution behavior of polyvinyl alcohol (PVA) supports fabricated by MEX. The measured crystallinity [...] Read more.
Material extrusion (MEX) commonly requires support structures, and their rapid removal is essential for improving overall process efficiency. This study investigates the effect of nozzle speed on the crystallinity and dissolution behavior of polyvinyl alcohol (PVA) supports fabricated by MEX. The measured crystallinity values are 28.8%, 25.4%, and 23.7% at nozzle speeds of 20 mm/s, 60 mm/s, and 100 mm/s, respectively. Dissolution rates are measured as 0.2144%/min, 0.2378%/min, and 0.2544%/min at nozzle speeds of 20 mm/s, 60 mm/s, and 100 mm/s, respectively. These results demonstrate that nozzle speed is a key parameter that governs both crystallinity and dissolution behavior of PVA. As a result, higher nozzle speeds not only shorten fabrication time but also produce supports with lower crystallinity. Thus, support structures can be removed more quickly and efficiently at high nozzle speeds. This work provides a new perspective on accelerating support dissolution, demonstrating that PVA crystallinity can be tailored through process parameter control in MEX from a chemical viewpoint, rather than relying on conventional physical approaches. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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22 pages, 3704 KB  
Article
Phenol–Formaldehyde Adhesives Modified with Eucalyptus Lignin: The Advantages of Soda Lignin
by Leonardo Clavijo, Rodrigo Coniglio, Fabián Bermúdez, Juan Martín Rodao, Diego Passarella and Andrés Dieste
Polymers 2025, 17(24), 3319; https://doi.org/10.3390/polym17243319 - 16 Dec 2025
Viewed by 462
Abstract
This study investigates the performance of phenol–formaldehyde adhesives containing Eucalyptus lignin as an extender in their formulation. A commercial phenol–formaldehyde resin was used, and five different types of lignin were tested: (1) kraft lignin precipitated with carbon dioxide, (2) kraft lignin precipitated with [...] Read more.
This study investigates the performance of phenol–formaldehyde adhesives containing Eucalyptus lignin as an extender in their formulation. A commercial phenol–formaldehyde resin was used, and five different types of lignin were tested: (1) kraft lignin precipitated with carbon dioxide, (2) kraft lignin precipitated with sulfuric acid, (3) soda lignin precipitated with hydrochloric acid, (4) soda lignin precipitated with sulfuric acid, and (5) a second soda lignin where the wood underwent a phosphoric acid extraction process prior to alkaline extraction. The lignins were used both unmodified and activated through three different processes: hydroxymethylation, phenolysis in an acidic medium, and alkaline phenolysis. Adhesives were formulated with substitution percentages of the base resin ranging from 10% to 60%, in addition to a reference adhesive that contained no lignin. Wooden test specimens were manufactured to determine the tensile shear strength. Results indicate that best performance is achieved when lignins are activated through hydroxymethylation and when soda lignin is used. Under optimal conditions, it is possible to replace at least 45% of the base resin with activated Eucalyptus soda lignin, which represents a reduction of at least 30% in the cost of the final adhesive. This substitution results in a 46% increase in adhesive strength compared to the base adhesive (without lignin). These findings suggest that the valorization Eucalyptus soda lignin could have significant economic and environmental benefits. Full article
(This article belongs to the Special Issue Advances in Applied Lignin Research)
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36 pages, 4597 KB  
Article
Local Relaxation Phenomena in Epoxy Resins in the Temperature Range from −150 °C to +150 °C
by Viktor A. Lomovskoy, Dmitry A. Trofimov, Svetlana A. Shatokhina, Nadezhda Yu. Lomovskaya and Igor D. Simonov-Emelyanov
Polymers 2025, 17(24), 3318; https://doi.org/10.3390/polym17243318 - 16 Dec 2025
Viewed by 346
Abstract
This study and theoretical analysis of local relaxation processes and their physicomechanical and physicochemical characteristics in uncured epoxy oligomers DER-330, ED-20, ED-16 and ED-8 were carried out in the dynamic mode of freely damped torsional oscillations excited in specimens of the investigated systems. [...] Read more.
This study and theoretical analysis of local relaxation processes and their physicomechanical and physicochemical characteristics in uncured epoxy oligomers DER-330, ED-20, ED-16 and ED-8 were carried out in the dynamic mode of freely damped torsional oscillations excited in specimens of the investigated systems. Internal friction spectra and temperature dependences of the frequency of free damped oscillations were obtained within the temperature range covering both the solid and liquid states of the epoxy oligomers. Based on the phenomenological models of a standard linear solid and the Maxwell model, the energetic and relaxation characteristics for each local dissipative process, as well as the temperature changes in strength properties (considering the defects of the shear modulus of the relaxation process) of the system as a whole, were calculated. Full article
(This article belongs to the Section Polymer Physics and Theory)
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29 pages, 2299 KB  
Article
Eco-Friendly Plant-Derived Fillers (Ginseng, Lemongrass, Turmeric, Wood Flour) for Elastomeric Composites Containing Natural and Chloroprene Rubbers (NR/CR)
by Aleksandra Smejda-Krzewicka
Polymers 2025, 17(24), 3317; https://doi.org/10.3390/polym17243317 - 16 Dec 2025
Viewed by 343
Abstract
This work aimed to investigate the properties of cross-linked elastomeric blends based on natural rubber (NR) and chloroprene rubber (CR), incorporating plant-derived fillers as environmentally friendly additives. The selected eco-friendly biofillers included ginseng, lemongrass, turmeric, or wood flour. In situ surface modification with [...] Read more.
This work aimed to investigate the properties of cross-linked elastomeric blends based on natural rubber (NR) and chloroprene rubber (CR), incorporating plant-derived fillers as environmentally friendly additives. The selected eco-friendly biofillers included ginseng, lemongrass, turmeric, or wood flour. In situ surface modification with n-octadecyltrimethoxysilane was carried out to enhance the compatibility between the fillers and the elastomeric matrix. The results showed that both unmodified and silane-modified plant-based fillers can be effectively used in NR/CR composites, yielding vulcanizates with favorable performance characteristics. The ginseng-filled composite exhibited the highest degree of cross-linking and superior mechanical strength among the tested materials. Turmeric, in both its unmodified and silane-treated forms, contributed to the greatest resistance against aging factors. Notably, the silane-modified wood flour filler significantly improved tear resistance, nearly doubling that of the unfilled rubber. Overall, these novel rubber composites demonstrate not only promising functional properties but also considerable ecological and economic advantages. Full article
(This article belongs to the Special Issue Eco-Friendly Polymer-Based Materials: Design and Applications)
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23 pages, 1862 KB  
Article
Computational Environmental Impact Assessment of an Enhanced PVC Production Process
by Arelmys Bustamante Miranda, Segundo Rojas-Flores and Ángel Darío González-Delgado
Polymers 2025, 17(24), 3316; https://doi.org/10.3390/polym17243316 - 16 Dec 2025
Viewed by 511
Abstract
Poly(vinyl chloride) (PVC) is one of the most widely used polymers due to its strength, low cost, and light weight. Industrial production is mainly conducted by suspension polymerization, which facilitates the control of the emissions of vinyl chloride monomer (VCM), a known carcinogen. [...] Read more.
Poly(vinyl chloride) (PVC) is one of the most widely used polymers due to its strength, low cost, and light weight. Industrial production is mainly conducted by suspension polymerization, which facilitates the control of the emissions of vinyl chloride monomer (VCM), a known carcinogen. However, the process consumes large amounts of water and energy and generates residual compounds such as polyvinyl alcohol (PVA) and polymerization initiators, which must be properly managed to mitigate environmental impacts. To improve sustainability, this study applied mass- and energy-integration strategies together with a zero-liquid-discharge (ZLD) water-regeneration system that uses sequential aerobic and anaerobic reactors to recirculate process water with reduced PVA. Although these measures reduce resource consumption, they can displace or intensify other impacts; therefore, a comprehensive evaluation of the system is necessary. Accordingly, the objective of this study is to quantify and compare the potential environmental impacts (PEIs) of the improved PVC production process through a scenario-based assessment using a waste reduction algorithm (WAR). This is applied to four operating scenarios in order to identify the stages and flows that contribute most to the environmental burden. According to our literature review, there is limited published evidence that simultaneously combines mass/energy integration and a ZLD system in PVC processes; thus, this work provides an integrated assessment useful for industrial design. The environmental performance of the improved process was evaluated using WAR GUI software (v 1.0.17, which quantifies PEIs in categories such as toxicity, climate change, and acidification. Four scenarios were compared: Case 1 (excluding both product and energy), Case 2 (product only), Case 3 (energy only), and Case 4 (product and energy). The total PEI increased from 2.46 PEI/day in Case 1 to 6230 PEI/day in Case 4, with the largest contributions from acidification (5140 PEI/day) and global warming (496 PEI/day), mainly due to natural gas consumption (5184 GJ/day). In contrast, Cases 1 and 2 showed negative PEI values (−3160 and −2660 PEI/day), indicating that converting the toxic VCM (LD50: 500 mg/kg; ATP: 26 mg/L) into PVC (LD50: 2000 mg/kg; ATP: 100 mg/L) can reduce the environmental burden in certain respects. In addition, the ZLD system contributed to maintaining low aquatic toxicity in Case 4 (90.70 PEI/day). Full article
(This article belongs to the Special Issue Biodegradable and Functional Polymers for Food Packaging)
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18 pages, 3920 KB  
Article
Chitosan from Virgin and SFE-Spent Fungi as a Raw Material for Disinfecting Gels
by Maria-Beatrice Coltelli, Marco Santin, Giulio Panicucci, Andrea Lazzeri, Stefano De Trovato, Simone Arca, Emilio D’Alessandro, Daniele Pietra, Francesca Cartoni and Antonella Castagna
Polymers 2025, 17(24), 3315; https://doi.org/10.3390/polym17243315 - 16 Dec 2025
Viewed by 405
Abstract
The valorization of extraction residues from biomass waste through a cascade approach contributes significantly to promote circular economy practices and facilitates the transition toward more sustainable functional materials, like chitosan. Virgin and spent fungal biomass, previously subjected to supercritical fluid extraction (SFE) using [...] Read more.
The valorization of extraction residues from biomass waste through a cascade approach contributes significantly to promote circular economy practices and facilitates the transition toward more sustainable functional materials, like chitosan. Virgin and spent fungal biomass, previously subjected to supercritical fluid extraction (SFE) using CO2, was further processed through demineralization and deproteinization to isolate chitin. This chitin was then deacetylated to obtain chitosan, and the yield of each step was evaluated. Although the extraction process requires further optimization, all the samples were characterized using infrared spectroscopy to assess compositional changes resulting from the treatments and compared with commercial counterparts. Chitosan solutions in acidic water were used to formulate hydroalcoholic gels, with ethanol pretreatment enabling compatibility between chitosan and alcohol. This study highlights the potential of chitosan—sourced from shrimps or fungi—as a sustainable raw material for disinfecting-gel applications, offering promising insights into its role in polymer-based formulations. Full article
(This article belongs to the Special Issue Sustainable Polymers: Green Synthesis and Functional Applications for Energy, Environment and Healthcare)
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