Polymers

16 pages, 3640 KB

Open AccessArticle

Reaction Kinetics of the Synthesis of Polymethoxy Butyl Ether from n-Butanol and Trioxane with Acid Cation-Exchange Resin Catalyst

by Xue Wang, Linyu Lu, Qiuxin Ma, Hongyan Shang and Lanyi Sun

Polymers 2025, 17(23), 3137; https://doi.org/10.3390/polym17233137 - 25 Nov 2025

Abstract

Polymethoxy butyl ether (BTPOM_n), a novel diesel additive developed for suppressing incomplete combustion emissions, was synthesized via an optimized batch slurry method employing n-butanol and trioxane (TOX) over NKC-9 acid cation-exchange resin (90–110 °C). A comprehensive kinetic model elucidated the reaction [...] Read more.

Polymethoxy butyl ether (BTPOM_n), a novel diesel additive developed for suppressing incomplete combustion emissions, was synthesized via an optimized batch slurry method employing n-butanol and trioxane (TOX) over NKC-9 acid cation-exchange resin (90–110 °C). A comprehensive kinetic model elucidated the reaction mechanism, addressing competitive pathways governing both main product formation and key side reactions—specifically polyoxymethylene hemiformals (HD_n) and polyoxymethylene glycols (MG) generation. As the first detailed kinetic investigation of BTPOM_n synthesis, this work provides a fundamental dataset and a robust predictive model that are crucial for process intensification and reactor design. Hybrid optimization integrating genetic algorithms with nonlinear least-squares regression achieved robust parameter estimation, with model predictions showing excellent agreement with experimental data. Thermal effects significantly influenced reaction rates, enhancing decomposition and propagation processes with increasing temperature. Optimal catalyst loading was identified at 3 and 6 wt.%, balancing reaction acceleration and byproduct suppression. Temperature-dependent equilibrium revealed chain length regulation through growth and depolymerization processes. This mechanistic understanding enables predictive reactor design for cleaner fuel additive synthesis. It provides critical insights for developing emission-control technologies in diesel engine systems. Full article

(This article belongs to the Section Polymer Chemistry)

17 pages, 4746 KB

Open AccessArticle

Analysis of the Effect of Fabrication Parameters on the Properties of Biopolymer Coatings Deposited on Ti13Zr13Nb Alloy

by Michał Bartmański and Kamila Sionek

Polymers 2025, 17(23), 3136; https://doi.org/10.3390/polym17233136 - 25 Nov 2025

Abstract

This work describes the preparation and characterization of chitosan-based biopolymer coatings containing silver, zinc, and hydroxyapatite nanoparticles deposited on the Ti13Zr13Nb alloy by the EPD method. It was intended to evaluate the influence of surface pretreatments and deposition parameters on the structural, electrochemical, [...] Read more.

This work describes the preparation and characterization of chitosan-based biopolymer coatings containing silver, zinc, and hydroxyapatite nanoparticles deposited on the Ti13Zr13Nb alloy by the EPD method. It was intended to evaluate the influence of surface pretreatments and deposition parameters on the structural, electrochemical, and biological properties of coatings. The morphology and composition were characterized by means of SEM/EDS, AFM, XRD, and FTIR analysis. The obtained results indicated uniform continuous layers with homogeneously distributed nanoparticles and the presence of characteristic functional groups originating from chitosan and hydroxyapatite. Corrosion investigations performed in SBF solution revealed a significant enhancement in corrosion resistance for chitosan/nanoAg/nanoZn/nanoHAp coatings, reflected in a drastic decrease in corrosion current density compared with uncoated Ti13Zr13Nb alloy. The contact angle measurements confirmed their hydrophilic nature, which favors better biointegration ability. Biological tests (MTT and LDH) performed on human osteoblasts (hFOB 1.19) confirmed high biocompatibility (>85% cell viability) in the case of all coatings with the addition of hydroxyapatite, whereas in the case of coatings without HAp, cytotoxicity was observed, probably due to the uncontrolled release of metallic nanoparticles. These findings suggest that the presence of hydroxyapatite in chitosan-based coatings efficiently enhances corrosion protection and cytocompatibility, showing very good prospects for biomedical applications such as the surface modification of titanium implants. Full article

(This article belongs to the Special Issue Biodegradable Polymers to Biomedical and Packaging Applications, 2nd Edition)

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40 pages, 2097 KB

Open AccessReview

Advances in Membranes Based on PLA and Derivatives for Oil–Water Separation

by Weijun Liang, Akshay Verma, Olga Martin, Gaurav Sharma and Alberto García-Peñas

Polymers 2025, 17(23), 3135; https://doi.org/10.3390/polym17233135 - 25 Nov 2025

Abstract

The continuously growing amount of oily wastewater from industrial, domestic, and natural sources poses a major threat to water sustainability, and thus efficient oil–water separation techniques are of utmost relevance. Membrane separation has been a popular approach due to ease of handling, high [...] Read more.

The continuously growing amount of oily wastewater from industrial, domestic, and natural sources poses a major threat to water sustainability, and thus efficient oil–water separation techniques are of utmost relevance. Membrane separation has been a popular approach due to ease of handling, high performance, and versatility. Among all the membrane materials, polylactic acid (PLA) and its derivatives have been of interest as green materials because of their renewability, biocompatibility, and biodegradability. PLA possesses special merits, including low density, high permeability, and high thermal stability. Despite its advantages, PLA also has some demerits, such as brittleness, low tensile strength, and poor heat resistance. These limitations are addressed by PLA-based membranes that are generally reinforced using fillers, surface modification, and structure optimization methods. This review provides a comprehensive overview of recent developments of PLA and its derivatives for oil–water separation, with an emphasis on membrane design, fabrication methods, and porosity enhancement strategies. Some significant fabrication processes like Thermally Induced Phase Separation (TIPS), Nonsolvent-Induced Phase Separation (NIPS), and Freeze Solidification Phase Separation (FSPS) are elaborately addressed. In addition, the review emphasizes methods to improve porosity, mechanical strength, and fouling resistance while maintaining biodegradability. By reviewing recent progress and remaining challenges, this review outlines the future potential of PLA membranes and aims to inspire more research on green, efficient oil–water separation. Full article

(This article belongs to the Special Issue Emerging Trends in Polymer Engineering: Polymer Connect-2024)

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17 pages, 3528 KB

Open AccessArticle

Environmental Degradation of Footbed Materials Under Different Conditions

by Asis Patnaik, Sudhakar Muniyasamy and Ashvani Goyal

Polymers 2025, 17(23), 3134; https://doi.org/10.3390/polym17233134 - 25 Nov 2025

Abstract

Different types of polymeric materials are used as footbeds in shoes. Environmental degradation behavior of polymeric footbed materials is an important parameter for understanding materials’ environmental footprint. Most of the previous studies focus on geotextiles, polymeric insulation materials, and exposure behaviors that are [...] Read more.

Different types of polymeric materials are used as footbeds in shoes. Environmental degradation behavior of polymeric footbed materials is an important parameter for understanding materials’ environmental footprint. Most of the previous studies focus on geotextiles, polymeric insulation materials, and exposure behaviors that are not the same due to the nature of applications of geotextiles and insulations being completely different from the footbeds. There is a lack of studies to understand artificial weathering, the influence of physical–chemical factors, and the subsequent behavior of different types of footbeds. In this paper, we have selected three needle-punched nonwoven footbed materials and studied their environmental degradation behavior by subjecting them to artificial weathering using different exposure durations, viz. 120 h, 240 h, and 360 h. The physical–chemical properties of polymeric footbed materials were characterized by Fourier-Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and thermogravimetric analysis (TGA). The selected polymeric footbed materials were made from recycled polyester (RPET), hemp, and shoddy fibers. Furthermore, the RPET footbed was tested for biodegradation in soil and compost conditions for 120 days. The footbed materials were also tested for physical and performance (tensile and abrasion resistance) properties. Hemp footbed materials undergo abiotic degradation after 120 h, but in the case of RPET, it undergoes abiotic degradation after 360 h, resulting in a fragmentation process due to synergistic effects of chemical and hydrolytic degradations. From the DSC results, RPET undergoes a slight thermal transition under abiotic degradation after 360 h, indicating that environmental abiotic factors influence degradation behavior. The tensile and abrasion resistance properties of RPET were the highest, followed by hemp and shoddy materials. The tensile strength range of the materials was between 50.74 and 851.44 N. The weight loss range after abrasion resistance was 0.016–0.014%. From the RPET biodegradation test in soil and compost conditions, the evolved CO₂ was 20% and 59%, respectively, after 110 days. The DSC and TGA results indicate that the hemp footbed materials have a higher rate of abiotic degradation as compared to the RPET and shoddy footbed materials. From the RPET biodegradation test in soil and compost conditions, the CO₂ degradation values were 20% and 59%, respectively. The obtained degradation results indicate that the synergistic effect of abiotic and biotic conditions greatly influences footbed materials’ biodegradation under natural environmental conditions. Full article

(This article belongs to the Special Issue New Insights into Fiber-Based Materials)

12 pages, 2410 KB

Open AccessArticle

Modulating Cell–Scaffold Interaction via dECM-Decorated Melt Electrowriting PCL Scaffolds

by Wenchao Li, Xiang Gao and Peng Zhang

Polymers 2025, 17(23), 3133; https://doi.org/10.3390/polym17233133 - 25 Nov 2025

Abstract

Aligned fibrous scaffolds are essential for directing soft-tissue regeneration, yet synthetic polymers lack native biochemical cues. To bridge this gap, bioactive and anisotropic scaffolds were developed by combining melt electrowriting (MEW) with decellularized extracellular matrix (dECM) decoration to enhance cell–scaffold interactions for soft [...] Read more.

Aligned fibrous scaffolds are essential for directing soft-tissue regeneration, yet synthetic polymers lack native biochemical cues. To bridge this gap, bioactive and anisotropic scaffolds were developed by combining melt electrowriting (MEW) with decellularized extracellular matrix (dECM) decoration to enhance cell–scaffold interactions for soft tissue engineering. Porous polycaprolactone (PCL) scaffolds with aligned microfibers and tunable pore architectures (aspect ratios 1:1, 1:2, and 1:3) were fabricated via MEW and subsequently coated with porcine skeletal muscle dECM using a dip-gelation method. Comprehensive surface characterization confirmed the presence and robust adhesion of the dECM coating on the PCL scaffolds, which concurrently enhanced surface hydrophilicity. Furthermore, mechanical testing demonstrated that the resulting composite scaffold retained the structural integrity required to meet the mechanical demands of tissue regeneration. In vitro studies using L929 fibroblasts demonstrated that dECM decoration significantly improved cell adhesion, proliferation, and alignment along the fiber direction. Notably, scaffolds with 1:1 and 1:2 aspect ratios supported the highest cell density and guided morphological elongation most effectively. These findings highlight the synergistic potential of topographical cues and biochemical signaling in scaffold design for functional tissue regeneration. Full article

(This article belongs to the Special Issue Advanced Polymeric Composites in Dentistry: Synthesis, Properties and Applications)

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27 pages, 3261 KB

Open AccessArticle

Development of Tailored Composite Biopolymer Film Formulations Using Minimally Refined Chitosan from American Lobster (Homarus americanus) Shell Waste for Different Food Packaging Applications

by Abhinav Jain, Beth Mason and Marianne Su-Ling Brooks

Polymers 2025, 17(23), 3132; https://doi.org/10.3390/polym17233132 - 25 Nov 2025

Abstract

The need for sustainable alternatives to petroleum-based plastic packaging has prompted interest in biodegradable biopolymer films. This study developed edible composite films using minimally refined chitosan from American lobster (Homarus americanus) shell waste combined with fish gelatin, glycerol, and sunflower oil. [...] Read more.

The need for sustainable alternatives to petroleum-based plastic packaging has prompted interest in biodegradable biopolymer films. This study developed edible composite films using minimally refined chitosan from American lobster (Homarus americanus) shell waste combined with fish gelatin, glycerol, and sunflower oil. A Box–Behnken design within a response surface methodology (RSM) framework was used to investigate the effects of these formulation variables on ten key film properties, including mechanical strength, water sensitivity, barrier performance, and optical characteristics. High-quality empirical models (R² ≥ 0.88) captured nonlinear, synergistic, and antagonistic interactions among the components, revealing trade-offs between competing attributes. Simultaneous multi-response optimization identified balanced formulations suited to various food packaging needs, including perishable, fresh, and dry products. Experimental validation of selected formulations confirmed model predictions within 5% error under laboratory conditions. Up to 68% of the inhibition activity against Escherichia coli was retained in a few composite formulations when compared with neat chitosan films, thus supporting their potential for active packaging. The key highlight of the present work is the use of crude chitosan derived from lobster shell waste, a low-cost, sustainable alternative to highly purified commercial sources, demonstrating the practical viability of marine byproduct valorization. Overall, this study advances the development of high-performance, application-specific biopolymer films and highlights RSM as an effective tool for optimizing multifunctional edible packaging materials. Future work should focus on enhancing antimicrobial functionality, evaluating real-world performance, and assessing consumer acceptance to support industrial adoption. Full article

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

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19 pages, 3337 KB

Open AccessArticle

High-Pressure Injection Molding of Isotactic Polypropylene and Its Nanocomposite with Multiwall Carbon Nanotubes: Enhancing Mechanical Properties Through γ-Form Crystallization

by Sivanjineyulu Veluri, Przemyslaw Sowinski, Joanna Bojda, Mariia Svyntkivska and Ewa Piorkowska

Polymers 2025, 17(23), 3131; https://doi.org/10.3390/polym17233131 - 25 Nov 2025

Abstract

Isotactic polypropylene (iPP), solidified under high-pressure in the orthorhombic γ-form, can exhibit enhanced mechanical properties compared to iPP crystallized in the common monoclinic α-form under atmospheric pressure. The aim of the study was to enhance the mechanical performance of injection-molded iPP and its [...] Read more.

Isotactic polypropylene (iPP), solidified under high-pressure in the orthorhombic γ-form, can exhibit enhanced mechanical properties compared to iPP crystallized in the common monoclinic α-form under atmospheric pressure. The aim of the study was to enhance the mechanical performance of injection-molded iPP and its nanocomposite containing 5 wt% of multiwall carbon nanotubes (MWCNTs) through high-pressure processing, which induced the formation of the γ-phase. Initially, the materials were crystallized in a high-pressure cell. To simulate the conditions during molding, crystallization was carried out by pressurizing the molten polymer to 250 MPa. For comparison, crystallization was also performed during cooling under 200 MPa and 1.4 MPa. Subsequently, the injection molding was conducted under optimized conditions, under pressure of 250 MPa, to promote the formation of the γ-phase, and, for comparison, under 20 MPa, to favor the α-phase formation. The injection-molded nanocomposite crystallized in the γ-form, tested in compression, exhibited an elastic modulus, yield stress, and stress at break higher by approx. 50%, 35% and 40–50%, respectively, compared to injection-molded neat iPP solidified predominantly in the α-form. These results demonstrate that substantial improvements in mechanical performance can be achieved through the incorporation of MWCNTs into iPP and the optimization of high-pressure injection-molding conditions. Full article

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

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17 pages, 3258 KB

Open AccessArticle

Sustainable Cellulose- and Pectin-Rich Triboelectric Nanogenerator for Mechanical Energy Harvesting and Self-Powered Humidity Sensing

by Seongwan Kim, Farhan Akhtar, Shahzad Iqbal, Muhammad Muqeet Rehman and Woo Young Kim

Polymers 2025, 17(23), 3130; https://doi.org/10.3390/polym17233130 - 25 Nov 2025

Abstract

This study develops a high-performance triboelectric nanogenerator (TENG) through Citrullus lanatus rind powder (CLP) which originates from watermelon waste to generate sustainable power and detect humidity. The SEM and FTIR results showed that CLP contains a natural porous structure and multiple polar functional [...] Read more.

This study develops a high-performance triboelectric nanogenerator (TENG) through Citrullus lanatus rind powder (CLP) which originates from watermelon waste to generate sustainable power and detect humidity. The SEM and FTIR results showed that CLP contains a natural porous structure and multiple polar functional groups which improve both the charge transfer and retention capabilities. The CLP-TENG device operated in vertical contact–separation mode with PTFE as the counter layer to generate a 255 V open-circuit voltage and 30 µA short-circuit current and 35 µW peak power output at 4 Hz and 20 MΩ load. The device successfully charged a 4.7 µF capacitor to 5 V during a 80 s period and operated low-power electronic devices to prove its ability as a sustainable power source. The device output increased with increasing operating frequency while showing operation stability throughout more than 1000 cycles and seven days of continuous operation. The device demonstrated a strong humidity detection ability through its voltage response which decreased from 250 V to 120 V when the relative humidity rose from 30% to 90%. The research proves that agricultural waste can be transformed into environmentally friendly materials which perform well in green energy systems and environmental monitoring applications. Full article

(This article belongs to the Topic Advances and Innovations in Waste Management)

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11 pages, 2880 KB

Open AccessArticle

Calcium Ion-Induced Self-Assembly of Carboxylated Polyallylamine-graft-Poly(Ethylene Glycol) in an Aqueous Medium

by Junya Emoto, Yukiya Kitayama and Atsushi Harada

Polymers 2025, 17(23), 3129; https://doi.org/10.3390/polym17233129 - 25 Nov 2025

Abstract

Double hydrophilic copolymers (DHCs) can form nano-assemblies such as micelles and vesicles in aqueous media under certain environmental conditions. These assemblies have attracted much attention in both fundamental and applied research. To date, most studies on DHC self-assemblies have focused on block copolymers [...] Read more.

Double hydrophilic copolymers (DHCs) can form nano-assemblies such as micelles and vesicles in aqueous media under certain environmental conditions. These assemblies have attracted much attention in both fundamental and applied research. To date, most studies on DHC self-assemblies have focused on block copolymers rather than graft copolymers. In this study, we investigated using Ca²⁺ ions in an aqueous medium to induce the formation of carboxylated polyallylamine-graft-poly(ethylene glycol) (PAA-g-PEG) self-assemblies as a graft-type DHC. Dynamic light scattering measurements conducted under various conditions showed that the carboxylated PAA-g-PEG self-assemblies had a micellar structure with a core of Ca²⁺ ions/carboxylates surrounded by non-ionic poly(ethylene glycol) grafts. Confocal laser scanning microscopy showed that the carboxylated PAA-g-PEG self-assemblies were able to deliver Ca²⁺ ions into cells. These results show that carboxylated PAA-g-PEG self-assemblies formed in the presence of divalent metal ions have potential for future applications in the biomedical field. Full article

(This article belongs to the Section Polymer Chemistry)

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21 pages, 5907 KB

Open AccessArticle

Attenuation Impact on Acoustic Emission Signal Parameters in Damage Mechanisms Characterization of Composite Rebars

by Paweł Zielonka, Michał Smolnicki, Szymon Duda and Grzegorz Lesiuk

Polymers 2025, 17(23), 3128; https://doi.org/10.3390/polym17233128 - 25 Nov 2025

Abstract

Composite materials have been extensively used across numerous industries due to their exceptional specific strength and corrosive resistance. However, ensuring their mechanical performance and structural integrity remains a critical challenge. This study provides an in-depth investigation into the damage mechanisms occurring in composite [...] Read more.

Composite materials have been extensively used across numerous industries due to their exceptional specific strength and corrosive resistance. However, ensuring their mechanical performance and structural integrity remains a critical challenge. This study provides an in-depth investigation into the damage mechanisms occurring in composite rebars manufactured via a modified pultrusion process, with a special emphasis on carbon, glass, and hybrid continuous fiber-reinforced polymers with epoxy resin matrix subjected to static tensile loading. To reveal the damage development, the acoustic emission (AE) technique was employed. Given the inherent complexity of composite microstructures, multiple failure modes can occur simultaneously, often masked by background noise and attenuation effects. Therefore, the core objective of this research is to evaluate and quantify the influence of acoustic attenuation on damage assessment in composite materials. This study introduces an optimization approach to minimize discrepancies between signals captured by different sensors, thereby enhancing the reliability of AE data interpretation. Results reveal that attenuation is strongly dependent on signal travel distance, frequency spectrum, and sensor type. Importantly, a data correction methodology is proposed to mitigate these effects, improving the accuracy of damage detection. Among the analyzed AE parameters, the initial frequency emerged as the most reliable feature for identifying the origin of acoustic events within hybrid composite structures. This finding represents a significant step toward more precise, attenuation-compensated acoustic emission monitoring, offering improved insight into failure mechanisms and contributing to the development of smarter diagnostic tools for composite materials. Full article

(This article belongs to the Special Issue Polymers and Polymer Composite Structures for Energy Absorption)

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16 pages, 922 KB

Open AccessArticle

Effects of Cement Shade, Cementation, and Thermocycling on the Color Parameters and the Final Color of the SLA-Printed Photopolymer Resins

by Esra Kaynak Öztürk, Elif Yılmaz Biçer, Beyza Güney, Sina Saygılı, Nagehan Aktaş and Merve Bankoğlu Güngör

Polymers 2025, 17(23), 3127; https://doi.org/10.3390/polym17233127 - 25 Nov 2025

Abstract

This study investigated the effects of resin cement shade and thermocycling on the color parameters and final appearance of SLA-printed photopolymer resins. Specimens with a thickness of 1 mm were fabricated and categorized into eight groups based on four different cement shades (universal-A2, [...] Read more.

This study investigated the effects of resin cement shade and thermocycling on the color parameters and final appearance of SLA-printed photopolymer resins. Specimens with a thickness of 1 mm were fabricated and categorized into eight groups based on four different cement shades (universal-A2, clear, white, and opaque) and two applications (cementation and thermal aging). Differences in color parameters (ΔL*, Δa*, and Δb*) were measured after cement polymerization and thermocycling, and overall color differences (ΔE₀₀-1 and ΔE₀₀-2) were calculated. Two-way ANOVA revealed significant interactions between cement shade and thermocycling for ΔL*, Δa*, and Δb* (p < 0.05). After cementation, L* decreased for universal-A2, clear, and white cements, but increased for opaque cement. Furthermore, thermocycling altered L*, a*, and b* values differently among the experimental groups. Cement shade significantly influenced ΔE₀₀, with universal-A2 and clear cements showing higher values than white and opaque cements (p < 0.05). All ΔE₀₀ values exceeded the clinically acceptable limit (>1.8). The findings suggest that careful selection of the cement shade is therefore critical to achieving optimal esthetic outcomes with the tested 3D-printed resin. Formlabs SLA-printed permanent resin, although labeled as an A2 shade, behaves more like white or opaque shades, highlighting inconsistencies between labeled and actual color. Full article

(This article belongs to the Special Issue Resins for Additive Manufacturing, 2nd Edition)

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21 pages, 8033 KB

Open AccessArticle

Agar/Carboxymethyl Cellulose Blended Films with Green-Synthesised Silver Nanoparticles as a Sustainable Alternative for Food Packaging Applications

by Seyedeh Fatemeh Mirpoor, Alessio Massironi, Danielle Winning, Stella Lignou, Sameer Khalil Ghawi, Federico Trotta and Dimitris Charalampopoulos

Polymers 2025, 17(23), 3126; https://doi.org/10.3390/polym17233126 - 25 Nov 2025

Abstract

The shelf life of food can be affected by storage and transport conditions. The development of a biodegradable, eco-friendly active bioplastic for food packaging could delay food deterioration during these stages, while minimising the environmental impact of non-degradable conventional plastics. In this study, [...] Read more.

The shelf life of food can be affected by storage and transport conditions. The development of a biodegradable, eco-friendly active bioplastic for food packaging could delay food deterioration during these stages, while minimising the environmental impact of non-degradable conventional plastics. In this study, blended films of agar with carboxymethyl cellulose (CMC) were integrated with different concentrations of silver nanoparticles (AgNPs) that were produced by a green synthesis method. The incorporation of silver nanoparticles into the blended films increased the stiffness of the film and improved the water vapour barrier and hydrophobicity. The thermal stability and the Fourier transform infrared spectra of the films were not affected by the different concentrations of AgNPs incorporated. The film microstructure was affected by the concentration of AgNPs and resulted in an increase in the film’s pore size. Films with the highest concentration of AgNPs showed antibacterial activity against foodborne pathogens, L. monocytogenes, Staphylococcus aureus, Pseudomonas aeruginosa and E. coli, and provided the material with the highest UV protection and bio-disintegration in soil and simulated seawater environments compared to the other developed films. The developed agar/CMC blended films with improved physicochemical properties present a viable alternative to conventional plastics in active food packaging applications. Full article

(This article belongs to the Special Issue Biodegradable Polymers to Biomedical and Packaging Applications, 2nd Edition)

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18 pages, 1787 KB

Open AccessArticle

Evaluation of Acrylamide/α-Lipoic Acid Statistical Copolymers as Degradable Water-Soluble Kinetic Gas Hydrate Inhibitors

by Chong Yang Du, Milan Marić and Phillip Servio

Polymers 2025, 17(23), 3125; https://doi.org/10.3390/polym17233125 - 25 Nov 2025

Abstract

Readily degradable low-dose hydrate inhibitors are of great significance for flow assurance in the petroleum industry. Recently, α-lipoic acid (LA) was shown to undergo ring-opening reaction via reversible addition–fragmentation chain-transfer copolymerization with acrylamides to introduce labile disulfide bonds into the stable vinyl polymer [...] Read more.

Readily degradable low-dose hydrate inhibitors are of great significance for flow assurance in the petroleum industry. Recently, α-lipoic acid (LA) was shown to undergo ring-opening reaction via reversible addition–fragmentation chain-transfer copolymerization with acrylamides to introduce labile disulfide bonds into the stable vinyl polymer backbone. Here, LA was copolymerized with acryloyl morpholine (AM) to evaluate their performance as kinetic hydrate inhibitors. Degradability was confirmed for the copolymers with 20 mol.% LA (AM/LA20, M_n = 19 → 9 kDa) after disulfide reduction. Thermogravimetric analysis also indicated faster thermal degradation of AM/LA due to the incorporation of weaker S-S and S-C linkages. Increasing LA content reduced hydrophilicity, and the copolymers were treated with NaOH to ensure water solubility. However, at 700 ppm, poly(AM) homopolymer reduced methane consumption during hydrate growth to 54% with respect to the uninhibited system, while gas consumption for the carboxylate AM/LA20 reached 78%. An advantageous feature of LA is its carboxylic acid, allowing desired functionalities to be grafted onto the degradable copolymer. Isopropyl amine (IPAm) was coupled with LA to form an amide known to be effective during hydrate inhibition (LA(IPAm)). The copolymer AM/LA(IPAm)20 demonstrated better water solubility compared to the original AM/LA20. Furthermore, the desirable IPAm functionality allowed the hydrate inhibition to be re-established at 54%, nearly recovering the performance of the poly(AM) homopolymer. This article assesses the application of LA and LA derivatives as building blocks for degradable amide-based kinetic hydrate inhibitors by validating their degradability with material characterizations and their inhibition performance during structure I hydrate growth. Full article

(This article belongs to the Section Polymer Chemistry)

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19 pages, 2686 KB

Open AccessArticle

Preparation and Characterization of Thermo-Compressed Guar Gum/Microcrystalline Cellulose Composites for Applications in Sustainable Packaging

by Prasong Srihanam, Jenjira Jirum, Pakin Noppawan, Nuanchai Khotsaeng and Yodthong Baimark

Polymers 2025, 17(23), 3124; https://doi.org/10.3390/polym17233124 - 25 Nov 2025

Abstract

In this study, we prepared guar gum (GG) films using a compression molding technique for the first time, incorporating glycerol as a plasticizer and microcrystalline cellulose (MCC) as a reinforcing filler. The chemical structures, thermal properties, crystalline structures, phase morphology, mechanical properties, moisture [...] Read more.

In this study, we prepared guar gum (GG) films using a compression molding technique for the first time, incorporating glycerol as a plasticizer and microcrystalline cellulose (MCC) as a reinforcing filler. The chemical structures, thermal properties, crystalline structures, phase morphology, mechanical properties, moisture content, and film opacity of thermo-compressed GG films were investigated. The results show that using glycerol as a plasticizer enhanced the flexibility of the thermo-compressed GG film and promoted its crystallization. The incorporation of glycerol enhanced the thermal stability of the GG film matrix. The addition of MCC enhanced the tensile strength of the plasticized GG film; however, it resulted in a decrease in elongation at break. The incorporation of MCC in plasticized GG films resulted in enhanced opacity and a decrease in moisture content. Thermo-compressed GG films can be customized to exhibit various properties by adjusting the glycerol and MCC contents, making them suitable for a range of eco-friendly and sustainable packaging applications. Full article

(This article belongs to the Special Issue Cellulose-Based Polymer Composites and Their Emerging Applications)

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15 pages, 3772 KB

Open AccessArticle

Effects of Build Orientation and Loading Direction on the Compressive Behavior of Additively Manufactured Re-Entrant Auxetic Materials

by Mehmet Ermurat and Mevlut Safa Dag

Polymers 2025, 17(23), 3123; https://doi.org/10.3390/polym17233123 - 25 Nov 2025

Abstract

Additive manufacturing (AM) technologies, particularly Fused Deposition Modeling (FDM) and Digital Light Processing (DLP), offer viable solutions for producing Auxetic materials characterized by their negative Poisson’s ratio. This study investigates the influence of build orientation and loading direction on the mechanical behavior of [...] Read more.

Additive manufacturing (AM) technologies, particularly Fused Deposition Modeling (FDM) and Digital Light Processing (DLP), offer viable solutions for producing Auxetic materials characterized by their negative Poisson’s ratio. This study investigates the influence of build orientation and loading direction on the mechanical behavior of re-entrant honeycomb auxetic structures fabricated using both FDM- and LCD-based DLP techniques. Specimens were produced in three principal build orientations (X, Y, and Z) and subjected to compression along two directions (X and Y) to capture the anisotropic mechanical response. Standard PLA filament was used for FDM, while standard and tough resins were used for DLP. Uniaxial compression tests were conducted to evaluate maximum compressive stress, Poisson’s ratio, and energy absorption behavior. The results reveal significant anisotropy in mechanical performance depending on build orientation and printing technology. DLP-printed specimens exhibited more isotropic behavior compared to FDM due to superior interlayer adhesion. Furthermore, build orientation was found to have a pronounced effect on auxetic response and load-bearing capacity. This study highlights the critical importance of considering build orientation and loading direction during the design and manufacturing of auxetic structures, especially for applications requiring targeted mechanical performance. Full article

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

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26 pages, 1958 KB

Open AccessArticle

Nanocellulose Filled Bio-Based PVA/Chitosan Nanocomposites: Structure–Property Relationships Toward Advanced Food Packaging Films

by Konstantinos Papapetros, Georgios N. Mathioudakis, Dionysios Vroulias, Nikolaos Koutroumanis, Amaia Soto Beobide, Olympia Kotrotsiou, Giannis Penloglou, Konstantinos S. Andrikopoulos and George A. Voyiatzis

Polymers 2025, 17(23), 3122; https://doi.org/10.3390/polym17233122 - 24 Nov 2025

Abstract

Biodegradable chitosan/poly(vinyl alcohol) (PVA) composite films were reinforced either with nanocrystalline cellulose (CNC) or nano-lignocellulose (NLC) and evaluated across a polyparametric design of five matrix ratios and three filler levels for active food packaging applications. ATR-FTIR, DSC, XRD, and SEM demonstrated that 1–5% [...] Read more.

Biodegradable chitosan/poly(vinyl alcohol) (PVA) composite films were reinforced either with nanocrystalline cellulose (CNC) or nano-lignocellulose (NLC) and evaluated across a polyparametric design of five matrix ratios and three filler levels for active food packaging applications. ATR-FTIR, DSC, XRD, and SEM demonstrated that 1–5% nanocellulose loading induced a single relaxation temperature (T_g), homogenized the morphology, and enhanced the crystallinity of blend material, evidencing improved thermodynamic compatibility. SEM confirmed uniform filler dispersion up to 5% loading in PVA-rich matrices, whereas limited aggregation appeared in chitosan-dominant systems. CO₂ barrier property (CO₂ permeability coefficients) was diminished by more than two orders of magnitude and fell below 0.01 Barrer in CNC-filled 25-75 and NLC-filled 75-25 blends, while permeability to O₂ and N₂ remained undetectable under identical conditions. Meanwhile, Young’s modulus increased to 3.9 GPa, and tensile strengths of up to 109 MPa were achieved, without affecting the ductility in specific loading values. These data confirm that tailored selection of the filler/matrix combination, rather than elevated nanocellulose content, can simultaneously optimize barrier performance and mechanical integrity. The study therefore offers a scalable, water-based route for producing optically transparent nanocomposite membranes that satisfy either strict modified atmosphere or/and rigid packaging applications and advance the transition toward compostable/or even edible high-performance food contact materials. Full article

(This article belongs to the Special Issue Cellulose and Chitosan: Characterization, Modification and Application)

10 pages, 1372 KB

Open AccessArticle

Proof of Concept for a Novel Ultralight Pneumatic Telescopic Boom Fabricated via Additive Manufacturing for Space Applications

by Teodor Adrian Badea, Alexa-Andreea Crisan and Lucia Raluca Maier

Polymers 2025, 17(23), 3121; https://doi.org/10.3390/polym17233121 - 24 Nov 2025

Abstract

This study investigates the performance characteristics of a six-segment telescopic boom prototype, two meters in length, entirely fabricated through additive manufacturing using composite materials, with the aim of optimizing the system’s strength-to-weight ratio. To meet the requirements for lightweight and high-stiffness space structures, [...] Read more.

This study investigates the performance characteristics of a six-segment telescopic boom prototype, two meters in length, entirely fabricated through additive manufacturing using composite materials, with the aim of optimizing the system’s strength-to-weight ratio. To meet the requirements for lightweight and high-stiffness space structures, the study focuses on validating the concept from these perspectives. The current assembly prototype weighs 2154 g for a deployed length of 2 m and a stowed length of 428 mm. The pneumatic extension system demonstrated an average pressure response ranging from 0.40 bar to 1.36 bar under a payload of up to 7370 g. At this threshold, an average inclination of 5.96° and an average deployment time of 60 s were recorded. Under an increased payload of 11,345 g, the prototype exhibited an average inclination of 1.1° and an average deployment time of 30 s, with only three segments fully deployed. This limitation is attributed to the maximum allowable internal pressure of the pneumatic tube, approximately 2.2 bar, where the high frictional and binding forces between the segments exceeded the available pneumatic energy, prematurely interrupting the extension cycle. These findings confirm the applicability of additive manufacturing to complex deployable systems and establish the mechanical and pneumatic performance limits of this prototype. Full article

(This article belongs to the Special Issue 3D Printing Polymers: Design and Applications)

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19 pages, 6176 KB

Open AccessArticle

Prediction of Mechanical Properties of Injection-Molded Weld Lines of Glass Fiber-Reinforced Composites

by Zuguo Bao, Yunxiang Yan, You Zhang, Ruihan Dong, Weijian Han and Qing Liu

Polymers 2025, 17(23), 3120; https://doi.org/10.3390/polym17233120 - 24 Nov 2025

Abstract

The weld line has a great impact on the mechanical properties of injection-molded parts, especially large ones. Currently, there is still a lack of useful simulation tools to accurately predict the mechanical properties of weld lines. To solve this issue, this paper studies [...] Read more.

The weld line has a great impact on the mechanical properties of injection-molded parts, especially large ones. Currently, there is still a lack of useful simulation tools to accurately predict the mechanical properties of weld lines. To solve this issue, this paper studies the mechanical properties of weld lines in injection-molded glass fiber (GF)-reinforced composites and builds a mathematical model to predict these properties. This model combines polymer chain dynamics with fiber–matrix interfacial debonding mechanics, enabling multiscale characterization of weld line strength. The experimental results showed that injection temperature, injection pressure, and fiber content all affect the mechanical properties of weld lines, with fiber content exerting the most significant influence. To predict weld line strength, a mathematical model was established by integrating multiple simulation software and tools: Moldex3D for mold flow analysis, Digimat for material modeling, and Abaqus for multiscale mechanical analysis. Comparisons between the simulation and experimental results demonstrated high accuracy of the model (errors less than 10% for tensile strength and 3.5% for stiffness, respectively), which provides an effective tool for predicting the weld line performance of glass fiber-reinforced polypropylene composites. Full article

(This article belongs to the Special Issue 3D Printing and Molding Study in Polymeric Materials, 2nd Edition)

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20 pages, 5671 KB

Open AccessArticle

The Synthesis of Zinc Complex of Salicylaldehyde Serine Schiff Base and Assessment of Its Efficiency as a Heat Stabilizer for Poly(Vinyl Chloride)

by Feng Ye, Zhihao Yan, Haoran Ma, Kangjie Guo, Cheng You, Qingsong Zheng, Shafeng Lv, Xiaodong Wang, Qiufeng Ye, Yeqian Ge, Zhuanyong Zou and Chi Shen

Polymers 2025, 17(23), 3119; https://doi.org/10.3390/polym17233119 - 24 Nov 2025

Abstract

The zinc complex of salicylaldehyde serine Schiff base (ZnL) was synthesized from serine, salicylaldehyde, and zinc diacetate and subsequently applied as a heat stabilizer in poly(vinyl chloride) (PVC). The structure of ZnL was determined using elemental analysis, crucible thermogravimetric method, infrared spectroscopy, thermogravimetric [...] Read more.

The zinc complex of salicylaldehyde serine Schiff base (ZnL) was synthesized from serine, salicylaldehyde, and zinc diacetate and subsequently applied as a heat stabilizer in poly(vinyl chloride) (PVC). The structure of ZnL was determined using elemental analysis, crucible thermogravimetric method, infrared spectroscopy, thermogravimetric analysis and ¹H NMR spectra. The heat stability effect of ZnL for PVC was investigated using the Congo red and oven aging methods. The results indicated that PVC stabilized by ZnL exhibited a certain degree of original whiteness and long-term heat resistance. In contrast with PVC stabilized by ZnSt₂ and Ca/Zn, ZnL was found to be slightly inferior in terms of whiteness but superior in long-term heat resistance. It was observed that complexation of ZnL with CaSt₂ could enhance both the original whiteness and long-term heat resistance of PVC, while also alleviating the “zinc burning” phenomenon. In contrast, complexation with ZnSt₂ was found to promote “zinc burning” for PVC. Furthermore, the heat stability mechanism of ZnL for PVC was explored through experiments focusing on HCl absorption and active chlorine substitution. The results demonstrated that ZnL could replace active chlorine on the PVC molecule and absorb HCl gas. Finally, auxiliary heat stabilizers such as pentaerythritol (Pe), dibenzoyl methane (DBM), and epoxidized soybean oil (ESBO) were added to ZnL/CaSt₂ to evaluate their synergistic effects. It was found that ESBO in PVC exhibited the best synergistic effect with ZnL/CaSt₂ and was superior to those observed with DBM and Pe. When the ratio of ZnL/CaSt₂/ESBO was set at 0.6/2.4/0.9, PVC demonstrated the optimal thermal stability performance. Full article

(This article belongs to the Special Issue Recent Advances in Flame-Retardant Polymeric Materials)

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