Polymers

24 pages, 1287 KB

Open AccessArticle

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

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

Open AccessArticle

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

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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Graphical abstract

21 pages, 2502 KB

Open AccessArticle

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

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

Open AccessReview

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

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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45 pages, 50456 KB

Open AccessArticle

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

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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59 pages, 3495 KB

Open AccessReview

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

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)

23 pages, 5287 KB

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

T_{2}

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

Open AccessArticle

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

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, 2335 KB

Open AccessArticle

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

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)

15 pages, 2603 KB

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessCommunication

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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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