Polymers

33 pages, 2305 KB

Open AccessReview

Application of Polymers in Hydraulic Fracturing Fluids: A Review

by Amro Othman, Murtada Saleh Aljawad, Rajendra Kalgaonkar and Muhammad Shahzad Kamal

Polymers 2025, 17(18), 2562; https://doi.org/10.3390/polym17182562 - 22 Sep 2025

Viewed by 653

Multistage hydraulic fracturing significantly increased oil and gas production in the past two decades. After drilling, fracturing fluids are pumped into the formation to create fractures that provide pathways to the hydrocarbon. These fluids are usually viscous to provide the mechanical power to [...] Read more.

Multistage hydraulic fracturing significantly increased oil and gas production in the past two decades. After drilling, fracturing fluids are pumped into the formation to create fractures that provide pathways to the hydrocarbon. These fluids are usually viscous to provide the mechanical power to frack the formation and carry the proppants, which keep the fractures open. After fracking, the viscous gel should be broken to allow the flowback of the fluid to avoid formation damage. The key player in the fracturing fluid system is the polymer, which is responsible for the fluid viscosity of the system. All other additives are added to improve the polymer’s performance under different conditions and reduce formation damage. The formation damage appears as fine migration, residue precipitation, adsorption, and wettability alteration. All of these types are affected by the polymer types and behavior. This paper reviews the polymers used in fracturing treatments, their classifications, preparations, mechanisms, degradation behavior, and interactions with other fracturing fluid additives. It also covers their impact on the formation damage and environmental concerns raised with fracturing treatments, including spills and flaring activities. The paper discussed the cost of the main polymers used in fracturing fluids and suggested practical recommendations to select a robust, cost-effective polymer. By integrating these concepts, the review gives the researcher the necessary knowledge to design and prepare effective fracturing fluids tailored to a wide range of operational scenarios. Full article

(This article belongs to the Section Polymer Applications)

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16 pages, 1245 KB

Open AccessArticle

Sulfur Vulcanization and Material Properties of Polyhydroxyalkanoates with Unsaturated Side Chain

by Phimthong Khamjapo, Lucas Vinicius Santini Ceneviva, Yusuke Nakata, Yuki Miyahara and Takeharu Tsuge

Polymers 2025, 17(18), 2561; https://doi.org/10.3390/polym17182561 - 22 Sep 2025

Viewed by 478

Abstract

This study aimed to evaluate the physical properties and biodegradability of sulfur-vulcanized polyhydroxyalkanoates (PHAs) with unsaturated side chains. As a vulcanizable PHA, poly(3-hydroxybutyrate-co-3-hydroxy-5-hexenoate) [P(3HB-co-3H5HE)] was biosynthesized with a 3H5HE fraction of 3–47 mol% using recombinant Escherichia coli and subsequently [...] Read more.

This study aimed to evaluate the physical properties and biodegradability of sulfur-vulcanized polyhydroxyalkanoates (PHAs) with unsaturated side chains. As a vulcanizable PHA, poly(3-hydroxybutyrate-co-3-hydroxy-5-hexenoate) [P(3HB-co-3H5HE)] was biosynthesized with a 3H5HE fraction of 3–47 mol% using recombinant Escherichia coli and subsequently vulcanized with varying sulfur contents (2–20 per hundred resin, phr) in the presence of zinc oxide, stearic acid, and 2-mercaptobenzothiazole as curing agents. The vulcanized PHA copolymers were insoluble in chloroform, indicating the formation of a cross-linked network. Raman spectroscopy revealed the functional loss of the double bonds in the polymers. After the vulcanization with 5 phr sulfur, the tensile strength and elongation at break of P(3HB-co-47 mol% 3H5HE) increased from 0.6 MPa to 6.3 MPa and from 430% to 813%, respectively. This sample exhibited low tensile set (8%) after 200% elongation, indicating rubber-like properties. Although biodegradability decreased with increasing crosslink density, vulcanized P(3HB-co-3H5HE) exhibited a greater degradation potential than vulcanized rubber but was lower than that of non-vulcanized P(3HB-co-3H5HE). These findings demonstrate that sulfur vulcanization can enhance the resilience of unsaturated PHAs, making them suitable for elastomeric and environmental applications. Full article

(This article belongs to the Special Issue Advances in Functional Rubber and Elastomer Composites, 3rd Edition)

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30 pages, 8820 KB

Open AccessArticle

Deflection Control of Concrete Wide Beams Supporting Columns Using CFRP Composites and Honeycomb Plates

by Abdulaziz Baatiah, Hussein Elsanadedy, Aref Abadel, Husain Abbas, Tarek Almusallam and Yousef Al-Salloum

Polymers 2025, 17(18), 2560; https://doi.org/10.3390/polym17182560 - 22 Sep 2025

Viewed by 476

Abstract

In the Middle East, RC joist slab systems with wide beams are widely used for residential floors. However, when these beams support planted columns, excessive deflection beyond code limits is often observed, despite adequate flexural and shear design. This paper experimentally assesses, for [...] Read more.

In the Middle East, RC joist slab systems with wide beams are widely used for residential floors. However, when these beams support planted columns, excessive deflection beyond code limits is often observed, despite adequate flexural and shear design. This paper experimentally assesses, for the first time, the efficacy of using carbon-fiber-reinforced polymer (CFRP) sheets alone versus a novel hybrid system comprising CFRP sheets and CFRP/honeycomb plates in controlling deflection in RC wide beams with planted columns. Four RC wide beam specimens at half-scale, each featuring a planted column, were tested to failure. Two control specimens, the first one was designed to reflect standard construction practices. It was sufficiently designed in flexure and shear, but its deflection exceeded code requirements. The second was designed to satisfy the code deflection requirements. The remaining specimens were strengthened using two different techniques: one with externally bonded CFRP sheets and the other with the hybrid system. The findings demonstrated a marked improvement in the flexural performance of the retrofitted wide beams, with peak load increases of 65–71%, stiffness gains of 63–67%, and reduced deflections meeting serviceability requirements (deflection at peak load was reduced by 45–48%). Furthermore, an analysis procedure was developed to estimate the flexural strength and deflection of these beams. Full article

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

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27 pages, 8496 KB

Open AccessReview

Progress in Electromagnetic Wave Absorption of Multifunctional Structured Metamaterials

by Zhuo Lu, Luwei Liu, Zhou Chen, Changxian Wang, Xiaolei Zhu, Xiaofeng Lu, Hui Yuan and Hao Huang

Polymers 2025, 17(18), 2559; https://doi.org/10.3390/polym17182559 - 22 Sep 2025

Viewed by 644

Abstract

This review summarizes recent advances in multifunctional metamaterials (MF-MMs) for electromagnetic (EM) wave absorption. MF-MMs overcome the key limitations of conventional absorbers—such as narrow bandwidth, limited functionality, and poor environmental adaptability—offering enhanced protection against EM security threats in radar, aerospace, and defense applications. [...] Read more.

This review summarizes recent advances in multifunctional metamaterials (MF-MMs) for electromagnetic (EM) wave absorption. MF-MMs overcome the key limitations of conventional absorbers—such as narrow bandwidth, limited functionality, and poor environmental adaptability—offering enhanced protection against EM security threats in radar, aerospace, and defense applications. This review focuses on an integrated structure-material-function co-design strategy, highlighting advances in three-dimensional (3D) lattice architectures, composite laminates, conformal geometries, bio-inspired topologies, and metasurfaces. When synergized with multicomponent composites, these structural innovations enable the co-regulation of impedance matching and EM loss mechanisms (dielectric, magnetic, and resistive dissipation), thereby achieving broadband absorption and enhanced multifunctionality. Key findings demonstrate that 3D lattice structures enhance mechanical load-bearing capacity by up to 935% while enabling low-frequency broadband absorption. Composite laminates achieve breakthroughs in ultra-broadband coverage (1.26–40 GHz), subwavelength thickness (<5 mm), and high flexural strength (>23 MPa). Bio-inspired topologies provide wide-incident-angle absorption with bandwidths up to 31.64 GHz. Metasurfaces facilitate multiphysics functional integration. Despite the significant potential of MF-MMs in resolving broadband stealth and multifunctional synergy challenges via EM wave absorption, their practical application is constrained by several limitations: limited dynamic tunability, incomplete multiphysics coupling mechanisms, insufficient adaptability to extreme environments, and difficulties in scalable manufacturing and reliability assurance. Future research should prioritize intelligent dynamic response, deeper integration of multiphysics functionalities, and performance optimization under extreme conditions. Full article

(This article belongs to the Special Issue Application and Characterization of Multifunctional and Sustainable Polymers and Composites)

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18 pages, 3887 KB

Open AccessArticle

Tuning White-Light Emission of POSS-Based Fluorescent Hybrid Porous Polymers via Physical Blending for White LEDs

by Qiming Huo, Zhuo Lv, Shengyu Feng, Dengxu Wang and Hongzhi Liu

Polymers 2025, 17(18), 2558; https://doi.org/10.3390/polym17182558 - 22 Sep 2025

Viewed by 453

Abstract

The development of a straightforward strategy for preparing organic fluorescent materials, fine-tuning white-light emission, and subsequently constructing white light-emitting diodes (LEDs) is of great significance. Herein, we report on the modulation of white-light emission and the fabrication of white LEDs using polyhedral oligomeric [...] Read more.

The development of a straightforward strategy for preparing organic fluorescent materials, fine-tuning white-light emission, and subsequently constructing white light-emitting diodes (LEDs) is of great significance. Herein, we report on the modulation of white-light emission and the fabrication of white LEDs using polyhedral oligomeric silsesquioxane (POSS)-based fluorescent hybrid porous polymers (HPPs) through simple physical blending. Two HPPs, namely HPP-1 and HPP-2, which emit blue and red light, respectively, were synthesized via the efficient Heck reactions of octavinylsilsesquioxane with 4,4′-dibromobiphenyl and 1,3,6,8-tetrabromopyrene. By physically doping of HPP-1 and HPP-2 in variable ratios in solvent suspensions, it was discovered that white-light emission is significantly influenced by the concentrations of the materials and the excitation wavelength. Similar findings were also observed in the solid-state physical doping. An ideal white light emission with a CIE coordinate of (0.33, 0.33) can be achieved when excited at 380 nm with a mass ratio of HPP-1 to HPP-2 of 1:2. Finally, the two HPPs were dispersed in polysiloxane matrices, and a white LED with a CIE coordinate of (0.42, 0.36) was obtained. The LED exhibited a color rendering index of up to 90 and a correlated color temperature of 2858 K, realizing warm white light emission. This simple and convenient white-light regulation strategy holds great promise for application in the development of novel white LEDs based on organic fluorescent porous materials. Full article

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35 pages, 3108 KB

Open AccessReview

Data-Driven Optimization of Discontinuous and Continuous Fiber Composite Processes Using Machine Learning: A Review

by Ivan Malashin, Dmitry Martysyuk, Vadim Tynchenko, Andrei Gantimurov, Vladimir Nelyub and Aleksei Borodulin

Polymers 2025, 17(18), 2557; https://doi.org/10.3390/polym17182557 - 22 Sep 2025

Viewed by 765

Abstract

This paper surveys the application of machine learning in fiber composite manufacturing, highlighting its role in adaptive process control, defect detection, and real-time quality assurance. First, the need for ML in composite processing is highlighted, followed by a review of data-driven approaches—including predictive [...] Read more.

This paper surveys the application of machine learning in fiber composite manufacturing, highlighting its role in adaptive process control, defect detection, and real-time quality assurance. First, the need for ML in composite processing is highlighted, followed by a review of data-driven approaches—including predictive modeling, sensor fusion, and adaptive control—that address material heterogeneity and process variability. An in-depth analysis examines six case studies, among which are XPBD-based surrogates for RL-driven robotic draping, hyperspectral imaging (HSI) with U-Net segmentation for adhesion prediction, and CNN-driven surrogate optimization for variable-geometry forming. Building on these insights, a hybrid AI model architecture is proposed for natural-fiber composites, integrating a physics-informed GNN surrogate, a 3D Spectral-UNet for defect segmentation, and a cross-attention controller for closed-loop parameter adjustment. Validation on synthetic data—including visualizations of HSI segmentation, graph topologies, and controller action weights—demonstrates end-to-end operability. The discussion addresses interpretability, domain randomization, and sim-to-real transfer and highlights emerging trends such as physics-informed neural networks and digital twins. This paper concludes by outlining future challenges in small-data regimes and industrial scalability, thereby providing a comprehensive roadmap for ML-enabled composite manufacturing. Full article

(This article belongs to the Special Issue Artificial Intelligence in Polymers)

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19 pages, 3880 KB

Open AccessArticle

Flame-Retardant Wood Scrimber/Plywood Composites: Preparation, Characterization, and Enhanced Structural Performance

by Liyuan Yao, Feifan Song, Ming Wei, Aijuan Wang, Xiaonan Xu, Zhilin Chen, Rui Rong and Peng Jiang

Polymers 2025, 17(18), 2556; https://doi.org/10.3390/polym17182556 - 22 Sep 2025

Viewed by 529

Abstract

Veneer-based wood composites are widely used for interior applications, yet their high flammability and smoke emission significantly limit their safe use in buildings. In this study, a multifunctional flame-retardant polyethylene adhesive film was developed via melt blending and hot pressing of a mixture [...] Read more.

Veneer-based wood composites are widely used for interior applications, yet their high flammability and smoke emission significantly limit their safe use in buildings. In this study, a multifunctional flame-retardant polyethylene adhesive film was developed via melt blending and hot pressing of a mixture of amino trimethylene phosphonic acid (ATMP), hydroxyethylidene diphosphonic acid (HDEP), melamine (MEL), and sodium alginate (SA). This film was laminated onto veneers to fabricate flame-retardant decorative plywood. Simultaneously, wood scrimber units for structural applications were prepared by impregnating wood with a flame-retardant system consisting of sodium silicate (Ss) and sodium tetraborate (St). These treated components were integrated to form a flame-retardant wood scrimber/plywood composite (AHM-S), with the wood scrimber as the core layer and the treated plywood as surface layers. Compared to the control, the AHM-S composite showed a 44.1% reduction in the second peak heat release rate (pk-HRR2), a 22.6% decrease in total heat release (THR), and a 12.7% reduction in maximum flame spread distance (MD_300°C). Moreover, the time to reach 275 °C on the unexposed side (T_275°C) was extended by 90.2%. These improvements are attributed to the synergistic flame-retardant effects of the surface film and impregnated core, which jointly suppress flame spread and delay thermal degradation. The composite demonstrates promising fire safety and mechanical performance for engineered wood applications. Full article

(This article belongs to the Special Issue Advanced Research on the Thermal Properties and Flame Retardancy of Polymer Composites, 2nd Edition)

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25 pages, 4992 KB

Open AccessArticle

Eco-Friendly Synthesis of Silver–Cellulose Nanocomposite Adsorbent from Agricultural Residues for Binary Dye System Remediation

by Doaa S. Al-Raimi, Reem M. Alghanmi, Ghalia S. Aljeddani and Ragaa A. Hamouda

Polymers 2025, 17(18), 2555; https://doi.org/10.3390/polym17182555 - 22 Sep 2025

Viewed by 398

Abstract

This work reports a one-step, green synthesis of silver-micro cellulose nanocomposite (Ag@Ce NCs) using Azadirachta indica A. Juss leaf extract to load micro-cellulose isolated from peanut shells with silver nanoparticles, followed by comprehensive physicochemical characterization (FTIR, TEM, EDX-SEM, zeta potential, and XRD). The [...] Read more.

This work reports a one-step, green synthesis of silver-micro cellulose nanocomposite (Ag@Ce NCs) using Azadirachta indica A. Juss leaf extract to load micro-cellulose isolated from peanut shells with silver nanoparticles, followed by comprehensive physicochemical characterization (FTIR, TEM, EDX-SEM, zeta potential, and XRD). The composite has pH_PZC ≈ 5.0 and was tested for simultaneous removal of methylene blue (MB) and safranin O (SO) under batch conditions across various pH levels, doses, contact times, initial concentrations, ionic strengths, and temperatures. The high removal efficiencies observed at pH 10 for MB and 6.0 for SO. The adsorption reached the maximum at 45 min before partially declining, indicating reversible binding on saturated surfaces. Isotherm study favored the Langmuir model, with similar affinities (K_L ≈ 0.106, and 0.110 L/mg) and monolayer capacities of 17.99 mg/g for MB and 14.90 mg/g for SO, suggesting non-selective competition on uniform sites. Kinetic data fitted the pseudo-second-order model, while thermodynamic analysis indicated mainly exothermic and physisorption interactions. Higher ionic strength reduced removal efficiency (at 1.0 M NaCl, %RE ≈ 33–48%), highlighting salt sensitivity typical of electrostatic attraction. The adsorbent maintained about 90% of its initial performance after five adsorption–desorption cycles in 0.1 M H₂SO₄, indicating excellent reusability. Overall, Ag@Ce NCs provide an inexpensive, eco-friendly, and reuseable platform for treating binary mixtures of cationic dyes. Full article

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

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16 pages, 12122 KB

Open AccessArticle

A Comparison Study on Polysaccharides Extracted from Citrus reticulata Blanco cv. Tankan Peel Using Five Different Methods: Structural Characterization and Immunological Competence

by Jinming Peng, Guangwei Chen, Ziyuan Lin, Shaoxin Guo, Yue Zeng, Qin Wang, Wenhua Yang and Jun Li

Polymers 2025, 17(18), 2554; https://doi.org/10.3390/polym17182554 - 22 Sep 2025

Viewed by 383

Abstract

This is the first work to screen an optimal extraction method for Citrus reticulata Blanco cv. Tankan peel polysaccharides (CPP). The CPP was extracted using hot water extraction (HWE), acid extraction (AAE), enzyme extraction (EAE), high-pressure extraction (HPE), and ultrasound extraction (UAE), named [...] Read more.

This is the first work to screen an optimal extraction method for Citrus reticulata Blanco cv. Tankan peel polysaccharides (CPP). The CPP was extracted using hot water extraction (HWE), acid extraction (AAE), enzyme extraction (EAE), high-pressure extraction (HPE), and ultrasound extraction (UAE), named CPP-W, CPP-A, CPP-E, CPP-P, and CPP-U, respectively. Results showed that CPP-A and CPP-P had higher extraction yields than other CPPs. The five CPPs varied chemically in molecular weight, monosaccharide composition, and microstructure, but shared similar IR spectra and core glycosidic linkages, indicating differential degradation while preserving core structures during extraction. Among these CPPs, CPP-A, CPP-E, and CPP-U exhibited stronger immunological activities, attributed to high galacturonic acid and low molecular weight. Moreover, CPPs significantly promoted secretion of cytokines (nitric oxide, NO; prostaglandin E₂, PGE₂; interleukin-6, IL-6; tumor necrosis factor-α, TNF-α) by activating downstream inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2)-related mitogen-activated protein kinases (MAPK) pathways. Overall, CPP-E possessed high extraction yield, low molecular weight, and strong immuno-stimulatory activity, suggesting that enzyme-assisted extraction was the optimal approach for extracting CPP. Full article

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

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32 pages, 3766 KB

Open AccessReview

Recent Advances in Marine-Derived Polysaccharide Hydrogels: Innovative Applications and Challenges in Emerging Food Fields

by Xinge Yi, Jing Xie and Jun Mei

Polymers 2025, 17(18), 2553; https://doi.org/10.3390/polym17182553 - 21 Sep 2025

Viewed by 1014

Abstract

Marine-derived polysaccharides (MPs) are a class of polysaccharides isolated and purified from marine organisms, which engage in various biological activities such as immunomodulation, anti-tumor, antibacterial, antioxidant, and anticoagulant activities. Excellent biocompatibility, biodegradability, and low toxicity make them ideal biomaterials for the preparation of [...] Read more.

Marine-derived polysaccharides (MPs) are a class of polysaccharides isolated and purified from marine organisms, which engage in various biological activities such as immunomodulation, anti-tumor, antibacterial, antioxidant, and anticoagulant activities. Excellent biocompatibility, biodegradability, and low toxicity make them ideal biomaterials for the preparation of hydrogels. In recent years, MP-based hydrogels have been successfully fabricated into various novel and smart hydrogels, triggering new transformations in the fields of biomedicine, cosmetics, and food. This review introduces the structural features, bioactive mechanisms, and safety evaluation of MPs. This review focuses on the latest application progress of MP-based hydrogels in the food field, including fruits and vegetables, meat products, aquatic products, bakery products, and health products, aiming to provide fundamental support for further research and development in the food industry. Full article

(This article belongs to the Special Issue Biodegradable and Biobased Polymers for Sustainable Food Applications)

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28 pages, 16645 KB

Open AccessArticle

Effects of Apple Vinegar, Mouthwashes, and Bleaching on Color Stability and Surface Properties of Fiber-Reinforced and Non-Reinforced Restorative Materials

by Kerem Yılmaz, Tuğçe Odabaş Hajiyev, Gökçe Özcan Altınsoy and Mehmet Mustafa Özarslan

Polymers 2025, 17(18), 2552; https://doi.org/10.3390/polym17182552 - 21 Sep 2025

Viewed by 556

Abstract

The aim of this study was to investigate the effects of apple cider vinegar (ACV), various mouthwashes and bleaching on the color and surface roughness of fiber strip-reinforced and unreinforced restorative materials. The materials were resin composite (RC), resin-nanoceramic (RNC), and polymer-infiltrated ceramic [...] Read more.

The aim of this study was to investigate the effects of apple cider vinegar (ACV), various mouthwashes and bleaching on the color and surface roughness of fiber strip-reinforced and unreinforced restorative materials. The materials were resin composite (RC), resin-nanoceramic (RNC), and polymer-infiltrated ceramic network (PICN); the mouthwashes were chlorhexidine with alcohol (CXA), chlorhexidine without alcohol (CX), herbal with alcohol (HRA), and herbal without alcohol (HR). Measurements were performed at T0 (baseline), T1 (1 day), T2 (2.5 days) and T3 (after bleaching). Analysis of variance (ANOVA) and Bonferroni analyses revealed that roughness from T0–T3 was highest for RNC and lowest for PICN. Regarding the solutions, the highest increase was in ACV and lowest in artificial saliva (p < 0.001). At T0–T2, color change (ΔE₀₀) and whiteness index change (ΔWI_D) were highest in CXA and lowest in HR. At T2–T3, ΔE₀₀ was highest in ACV, while ΔWI_D was highest in CXA (p < 0.001). Although the roughness exceeded the bacterial adhesion threshold, the effect of bleaching was not considerable. Color and whiteness changes generally did not exceed the acceptability threshold. Fiber strip position did not affect roughness. However, a strip in the middle layer had higher impact on color and whiteness than the one in the top layer. Full article

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

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26 pages, 2437 KB

Open AccessArticle

Interphase-Resolved Performance in PA6/TiO₂ Nanocomposite Fibers: Four-Phase Geometry Linking Structure to Mechanical and UV Protection

by Hailong Yu, Ping Liu, Xiaohuan Ji, Xiaoze Jiang and Bin Sun

Polymers 2025, 17(18), 2551; https://doi.org/10.3390/polym17182551 - 21 Sep 2025

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Abstract

Melt-spun PA6/TiO₂ fibers with TiO₂ modified by silane coupling agents KH550 and KH570 at 0, 1.6, and 4 wt% provide a practical testbed to address three fiber-centric gaps: transferable interphase quantification, interphase-resolved indications of compatibility, and a reproducible kinetics–structure–property link. This [...] Read more.

Melt-spun PA6/TiO₂ fibers with TiO₂ modified by silane coupling agents KH550 and KH570 at 0, 1.6, and 4 wt% provide a practical testbed to address three fiber-centric gaps: transferable interphase quantification, interphase-resolved indications of compatibility, and a reproducible kinetics–structure–property link. This work proposes, for the first time at fiber scale, a four-phase partition into crystal (c), crystal-adjacent rigid amorphous fraction (RAF-c), interfacial rigid amorphous fraction (RAF-i), and mobile amorphous fraction (MAF), and extracts an interfacial triad consisting of the specific interfacial area (S_v), polymer-only RAF-i fraction expressed per composite volume (Γ_i), and interphase thickness (t_i) from SAXS invariants to establish a quantitative interphase-structure–property framework. A documented SAXS/DSC/WAXS workflow partitions the polymer into the above four components on a polymer-only basis. Upon filling, Γ_i increases while RAF-c decreases, leaving the total RAF approximately conserved. Under identical cooling, DSC shows the crystallization peak temperature is higher by 1.6–4.3 °C and has longer half-times, indicating enhanced heterogeneous nucleation together with growth are increasingly limited by interphase confinement. At 4 wt% loading, KH570-modified fibers versus KH550-modified fibers exhibit higher α-phase orientation (Hermans factor f(α): 0.697 vs. 0.414) but an ~89.4% lower α/γ ratio. At the macroscale, compared to pure (neat) PA6, 4 wt% KH550- and KH570-modified fibers show tenacity enhancements of ~9.5% and ~33.3%, with elongation decreased by ~31–68%. These trends reflect orientation-driven stiffening accompanied by a reduction in the mobile amorphous fraction and stronger interphase constraints on chain mobility. Knitted fabrics achieve a UV protection factor (UPF) of at least 50, whereas pure PA6 fabrics show only ~5.0, corresponding to ≥16-fold improvement. Taken together, the SAXS-derived descriptors (S_v, Γ_i, t_i) provide transferable interphase quantification and, together with WAXS and DSC, yield a reproducible link from interfacial geometry to kinetics, structure, and properties, revealing two limiting regimes—orientation-dominated and phase-fraction-dominated. Full article

(This article belongs to the Section Polymer Fibers)

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20 pages, 5125 KB

Open AccessArticle

Scratch Resistance and Tribological Enhancement of Epoxy Composites Reinforced with Chopped Glass Fiber and Nano Silica Through Taguchi Analysis

by Elanur Ozun, Reyhan Ceylan, Mustafa Özgür Bora, Sinan Fidan, Satılmış Ürgün, Mehmet İskender Özsoy and Erman Güleç

Polymers 2025, 17(18), 2550; https://doi.org/10.3390/polym17182550 - 21 Sep 2025

Cited by 1 | Viewed by 454

Abstract

This study examines the incorporation of chopped glass fiber and nano-silica into epoxy, focusing on their effects on the tribological and mechanical properties. Three reinforcement ratios (1 wt.%, 3 wt.%, and 5 wt.%) were analyzed by scratch tests and profilometric analysis. The coefficient [...] Read more.

This study examines the incorporation of chopped glass fiber and nano-silica into epoxy, focusing on their effects on the tribological and mechanical properties. Three reinforcement ratios (1 wt.%, 3 wt.%, and 5 wt.%) were analyzed by scratch tests and profilometric analysis. The coefficient of friction (COF), scratch depth, and scratch width values of the unreinforced epoxy resin were measured as 0.45, 37.73 µm and 479 µm, respectively. The addition of glass fibers contributed to improved scratch performance by restricting material removal and stabilizing groove morphology, although higher fiber ratios caused an increase in COF. The results indicated that nano-silica increased scratch resistance with a COF of 0.42 at 5 wt.%, giving a scratch depth of 19.92 µm and a scratch width of 166 µm. Glass fiber also improved scratch performance, although there were high COF values for higher ratios, which could be due to the aggregation effect of the fibers. Statistical validation of the results was carried out through the Taguchi method and ANOVA analyses. These analyses showed that reinforcement type and ratio played an important role in scratch behavior. SEM analyses of worn surfaces showed that nano-silica can dissipate stress and minimize plastic deformation to yield improved scratch morphology. Overall, the results emphasize the complementary role of glass fiber and nano-silica reinforcements in improving the scratch resistance of epoxy resin for industrial applications. Full article

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

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19 pages, 3628 KB

Open AccessArticle

Additive Manufacturing of Bio-Based PA11 Composites with Recycled Short Carbon Fibers: Stiffness–Strength Characterization

by Christian Brauner, Thierry Bourquin, Julian Kupski, Lucian Zweifel, Mohammad Hajikazemi, Chester Houwink and Martin Eichenhofer

Polymers 2025, 17(18), 2549; https://doi.org/10.3390/polym17182549 - 20 Sep 2025

Viewed by 549

Abstract

Short carbon fiber-reinforced bio-based polyamide 11 (PA11) composites were developed in filament form for Additive Fusion Technology (AFT) 3D printing and benchmarked against injection-molded samples. Composites containing 15 and 25 weight percent (wt%) recycled carbon fibers (rCFs) were successfully extruded into 1.75 mm [...] Read more.

Short carbon fiber-reinforced bio-based polyamide 11 (PA11) composites were developed in filament form for Additive Fusion Technology (AFT) 3D printing and benchmarked against injection-molded samples. Composites containing 15 and 25 weight percent (wt%) recycled carbon fibers (rCFs) were successfully extruded into 1.75 mm diameter filaments, whereas higher fiber contents (35 wt%) led to brittle filament failure. AFT printing with subsequent consolidation produced short fiber composites with highly aligned fibers, while injection molding generated more randomly oriented microstructures. Mechanical testing revealed that AFT-printed composites in the fiber direction achieved significantly higher stiffness and comparable tensile strength to injection-molded counterparts. At 25 wt% fiber content, AFT 0° specimens reached an axial tensile modulus of 14.5 GPa, about 32% higher than injection-molded samples (11.0 GPa), with similar axial tensile strength (~123 vs. 126 MPa). However, AFT specimens displayed pronounced anisotropy: transverse (90°) properties dropped to ~2.3 GPa for transverse modulus and ~46–50 MPa transverse tensile strength, near matrix-dominated levels. Impact testing showed orientation-dependent toughness, with AFT 90° samples at 15% fiber content achieving the highest impact energy (76 kJ·m⁻²), while AFT 0° samples were ~30% lower than injection-molded equivalents. Dynamic mechanical analysis confirmed that AFT 0° composites maintained higher stiffness up to ~80 °C. Overall, these results demonstrate that aligned short fiber filaments enable high stiffness and strength performance comparable to injection molding, with the trade-off of anisotropy that must be carefully considered in design. This study is the first to demonstrate the feasibility of combining bio-based PA11 with recycled short carbon fibers in AFT printing, thereby extending additive manufacturing to sustainable and high-stiffness short fiber composites. Full article

(This article belongs to the Special Issue Development in Fiber-Reinforced Polymer Composites: 2nd Edition)

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20 pages, 3178 KB

Open AccessArticle

Catalyst Selection for Body-Temperature Curable Polyurethane Networks from Poly(δ-Decalactone) and Lysine Diisocyanate

by Marine Boursier, Aurelien Lebrun, Karine Parra, Sylvain Caillol, Claire Negrell and Julien Pinaud

Polymers 2025, 17(18), 2548; https://doi.org/10.3390/polym17182548 - 20 Sep 2025

Viewed by 458

Abstract

With aging, harsh working conditions or sports injuries, the meniscus can degrade, causing pains to the patient. Nowadays, the treatment consists of the surgical replacement of this cartilage. Since this procedure can lead to complications due to open wounds and potential infections, synthesizing [...] Read more.

With aging, harsh working conditions or sports injuries, the meniscus can degrade, causing pains to the patient. Nowadays, the treatment consists of the surgical replacement of this cartilage. Since this procedure can lead to complications due to open wounds and potential infections, synthesizing a polyurethane-based injectable joint filler represents an interesting alternative. In this study, poly(δ-decalactone)triol oligomers and Lysine diisocyanate were chosen as starting monomers to create an isocyanate-based prepolymer, because of their biocompatibility and liquid state at room temperature. Nevertheless, to fully replace the meniscus, the joint filler must crosslink in vivo, and this should occur in a short time window. Accordingly, in this work, we studied the catalytic activity of a range of relatively safe compounds for the alcohol/isocyanate addition reaction. A preliminary ¹H NMR kinetic study of the catalyzed addition of 1-butanol or 3-pentanol on lysine diisocyanate ethyl ester at body temperature has been performed to reach this objective. Among catalysts, stannous octoate was the most effective with either primary or secondary alcohol, allowing them to reach 92 and 80% alcohol conversion, respectively. In addition, the conversion of the primary and secondary isocyanates of lysine diisocyanate ethyl ester was monitored for all the catalysts and revealed different behaviors depending on the catalyst employed. Stannous octoate, unlike the others, showed a similar reactivity for primary and secondary isocyanates with conversions of 49 and 47%, respectively. Finally, when employing the most effective catalyst, curing of the poly(δ-decalactone) triisocyanate with glycerol at 35 °C provided a polyurethane elastomer that exhibits an elastic modulus of 519 kPa and a swelling index lower than 3% in PBS, making it suitable for injectable polyurethane joint filler application. Full article

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

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15 pages, 1775 KB

Open AccessArticle

An Effect of a Matrix Made of Cell Wall Polysaccharides from Apple on the Rheological Properties of Various Food Products

by Joanna Mierczyńska, Piotr Mariusz Pieczywek and Justyna Cybulska

Polymers 2025, 17(18), 2547; https://doi.org/10.3390/polym17182547 - 20 Sep 2025

Viewed by 354

Abstract

A texture-modifying food matrix (MPS) was obtained by micronizing apple cell polysaccharides and adding spray-dried low-methoxy pectins. This study aimed to demonstrate the effect of MPS addition on a versatile group of products, including instant soup, salad dressing, buttermilk, tomato juice, apple juice, [...] Read more.

A texture-modifying food matrix (MPS) was obtained by micronizing apple cell polysaccharides and adding spray-dried low-methoxy pectins. This study aimed to demonstrate the effect of MPS addition on a versatile group of products, including instant soup, salad dressing, buttermilk, tomato juice, apple juice, and instant kissel. The rheological properties of suspensions with two MPS concentrations added to these products were compared with those of the control. Additionally, the water holding and retention capacity, swelling capacity, and wetting angles of the MPS and its components were characterized to determine the technological properties of these products. Results show that the MPS proportionally increases viscosity and the thixotropic effect of all studied products, except buttermilk, in relation to concentration. In particular, very pronounced effects were obtained for apple, tomato juice, and salad dressing. All studied suspensions were classified as pseudoplastic fluids; the addition of MPS resulted in varying changes in pseudoplasticity, depending on the product. In summary, this study showed that MPS, as a natural and rich source of dietary fibre matrix, effectively alters rheological properties and may therefore be considered a substitute for other food additives currently used in the food industry. Full article

(This article belongs to the Special Issue Natural Polymers and Composites for Food Applications)

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16 pages, 1482 KB

Open AccessArticle

Room Temperature Synthesis of a Novel Quinolinoxazine, Polymerization and Flammability Studies

by Maria Laura Salum, Daniela Iguchi, Carlos Rodriguez Arza, Nora Pellegri, Hatsuo Ishida and Pablo Froimowicz

Polymers 2025, 17(18), 2546; https://doi.org/10.3390/polym17182546 - 20 Sep 2025

Viewed by 286

Abstract

A novel quinoline-containing benzoxazine resin, 8HQ-fa, has been successfully synthesized at room temperature using sustainable raw materials, such as 8-hydroxyquinoline and furfurylamine as the phenol and amine source, respectively. The chemical structure of the hereinafter referred to as quinolinoxazine is fully characterized [...] Read more.

A novel quinoline-containing benzoxazine resin, 8HQ-fa, has been successfully synthesized at room temperature using sustainable raw materials, such as 8-hydroxyquinoline and furfurylamine as the phenol and amine source, respectively. The chemical structure of the hereinafter referred to as quinolinoxazine is fully characterized by Fourier transform infrared spectroscopy (FT-IR), ¹H and ¹³C nuclear magnetic resonance spectroscopy (NMR), as well as by 2D ¹H–¹H nuclear Overhauser effect spectroscopy (NOESY) and ¹H–¹³C heteronuclear multiple quantum correlation (HMQC) NMR. Thermal properties and polymerization behavior of the monomer are studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The resulting polymer is also characterized in terms of its thermal and fire-related properties by DSC, TGA, and microscale combustion calorimetry (MCC). The resulting thermoset, poly(8HQ-fa), presents good thermal stability as evidenced by its T_g (201 °C), T_d5 and T_d10 (307 and 351 °C, respectively), and char yield (42%), and low flammability as determined by the LOI, heat release capacity, and total heat released values (34.3, 143 J/gK, and 10.8 kJ/g, respectively), making it a self-extinguishing thermoset. The combination of properties and advantages in the synthesis of 8HQ-fa, accompanied by a low polymerization temperature, suggests its great potential in the field of high-performance polymers. Full article

(This article belongs to the Section Polymer Chemistry)

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20 pages, 336 KB

Open AccessReview

Tooth-Whitening Agents and Polymer-Based Carriers: Efficacy, Safety, and Clinical Perspectives

by Pin-Yu Lin, Li-Nai Chen, Chien-Fu Tseng, Yi-Shao Chen, Hung-Yu Lin, Thi Thuy Tien Vo, Tzu-Yu Peng and I-Ta Lee

Polymers 2025, 17(18), 2545; https://doi.org/10.3390/polym17182545 - 20 Sep 2025

Viewed by 910

Abstract

Tooth whitening is increasingly sought in both clinical and home settings, raising concerns about the efficacy and safety of various whitening agents and their delivery systems. This narrative review compares the whitening performance and biocompatibility of active ingredients, including hydrogen peroxide, carbamide peroxide, [...] Read more.

Tooth whitening is increasingly sought in both clinical and home settings, raising concerns about the efficacy and safety of various whitening agents and their delivery systems. This narrative review compares the whitening performance and biocompatibility of active ingredients, including hydrogen peroxide, carbamide peroxide, activated charcoal, sodium bicarbonate, fluoride compounds, and blue covarine, with particular emphasis on the role of polymer-based carriers in formulation strategies. Hydrogen peroxide and carbamide peroxide remain the most effective agents for intrinsic whitening, but are associated with risks of enamel surface alterations, microhardness reduction, and potential cytotoxicity, particularly at higher concentrations. Sodium bicarbonate provides moderate whitening effects through extrinsic stain removal, while fluoride compounds play a supportive role by reducing demineralization and tooth sensitivity, thereby preserving enamel integrity. These properties make them valuable adjuncts or alternatives for patients with high sensitivity risks. Blue covarine offers immediate optical effects without inducing intrinsic color changes, whereas activated charcoal poses risks of enamel abrasion and surface roughness with limited long-term efficacy. Polymer-based carriers such as Carbopol gels, polyvinylpyrrolidone, and hydroxypropyl methylcellulose are incorporated into whitening formulations to improve viscosity, adhesion, and modulate the release of active ingredients. These polymers might help minimize diffusion of bleaching agents into deeper dental tissues, potentially reducing cytotoxic effects, and may improve handling characteristics. However, dedicated studies evaluating the unique advantages of polymers in different whitening systems remain limited. A comprehensive understanding of both the active ingredients and delivery technologies is critical to balancing esthetic outcomes with long-term oral health. From a clinical perspective, polymer-based carriers might contribute to reducing whitening-related tooth sensitivity, improving patient comfort, and providing more predictable treatment outcomes. Continued research is needed to clarify optimal formulations and application protocols, ensuring safer and more effective tooth-whitening practices in both clinical and home-use scenarios. Full article

(This article belongs to the Special Issue Applications of Polymer Biomedical Materials in Medicine and Dentistry)

12 pages, 804 KB

Open AccessArticle

Integrating Photon-Based Techniques to Probe Structural and Phonon Dynamics in Bacterial Cellulose

by Levente Csóka and Bunsho Ohtani

Polymers 2025, 17(18), 2544; https://doi.org/10.3390/polym17182544 - 20 Sep 2025

Viewed by 329

Abstract

Bacterial cellulose, a biopolymer synthesised by microorganisms, exhibits remarkable structural, optical, and electronic properties. This study utilised a range of photon- and electron-based techniques, including X-ray diffraction, proton nuclear magnetic resonance (¹H-NMR), photoacoustic spectroscopy, and scanning electron microscopy, to thoroughly characterise [...] Read more.

Bacterial cellulose, a biopolymer synthesised by microorganisms, exhibits remarkable structural, optical, and electronic properties. This study utilised a range of photon- and electron-based techniques, including X-ray diffraction, proton nuclear magnetic resonance (¹H-NMR), photoacoustic spectroscopy, and scanning electron microscopy, to thoroughly characterise BC. While XRD and NMR directly employ photons to probe the structure and composition, PAS indirectly converts absorbed photons into phonons to evaluate optoelectronic features. SEM revealed a dense nanofibrillar network with fibrils measuring 10–75 nm in diameter. XRD confirmed the crystalline nature of BC, identifying characteristic peaks associated with cellulose Iα. ¹H-NMR relaxation analysis differentiated between the ordered and disordered cellulose regions. PAS determined an optical bandgap of 2.97 eV and identified defect states between 3.6 and 2.9 eV, including a prominent peak at 3.35 eV, likely resulting from oxygen vacancies, hydroxyl modifications, or UV-induced rearrangements. These defects modify BC’s electronic structure, suggesting potential for bandgap engineering. The integration of these complementary techniques provides a multidimensional understanding of BC’s morphology, crystallinity, and electronic behaviour, underscoring its potential in bioelectronics, advanced composites, and biomedical applications. Full article

(This article belongs to the Special Issue Advances in Cellulose-Based Polymers and Composites, 2nd Edition)

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15 pages, 2285 KB

Open AccessArticle

Polymer Blend Spiking Method for Quantifying Polypropylene Variants in 100% Polypropylene Blends

by Meysam Hashemnejad and Ami Doshi

Polymers 2025, 17(18), 2543; https://doi.org/10.3390/polym17182543 - 20 Sep 2025

Viewed by 376

Abstract

Understanding the type of polypropylene (PP) in post-consumer recycled (PCR) PP is valuable for optimizing mechanical recycling approaches, especially when blending with virgin polymers for specific applications. However, accurately identifying and quantifying the various types of polypropylene, including isotactic Homo-PP (Homo-PP), Random-PP, and [...] Read more.

Understanding the type of polypropylene (PP) in post-consumer recycled (PCR) PP is valuable for optimizing mechanical recycling approaches, especially when blending with virgin polymers for specific applications. However, accurately identifying and quantifying the various types of polypropylene, including isotactic Homo-PP (Homo-PP), Random-PP, and non-crystalline PP components (such as xylene-soluble atactic PP and amorphous ethylene–propylene copolymers), presents significant challenges when dealing with materials composed entirely of polypropylene. To address this, we propose a solution-based crystallization elution fractionation (CEF) technique to determine the composition of different PP variants in PP blend systems. Our approach involves introducing a controlled amount of linear low-density polyethylene (LLDPE) into the 100% PP sample in solution, enabling the separation of Homo-PP from Random-PP. By applying established calibration curves, we quantitatively resolve the content of Homo-PP, Random-PP, and non-crystalline PP. The calibration is effective across the full composition window, enabling accurate quantification of Random-PP and Homo-PP from pure (100%) components to mixed systems spanning ~5 wt.% to 95 wt.% Random-PP. This comprehensive analysis offers valuable insights into the distribution of PP variants within the material, facilitating informed decision-making in recycling and material selection processes, ultimately enhancing the efficiency and sustainability of PP recycling operations. Full article

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

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15 pages, 2036 KB

Open AccessArticle

Effect of Degradation During Multiple Primary Mechanical Recycling Processes on the Physical Properties and Biodegradation of Commercial PLA-Based Water Bottles

by Cristina Muñoz-Shugulí, Diana Morán, Eliezer Velásquez, José Manuel López-Vilariño and Carol López-de-Dicastillo

Polymers 2025, 17(18), 2542; https://doi.org/10.3390/polym17182542 - 20 Sep 2025

Viewed by 597

Abstract

For sustainable development aligned with circular economy principles, the recycling of biopolymers such as polylactic acid (PLA) is of growing interest. In this study, the effect of primary recycling through repeated mechanical reprocessing was investigated. PLA water bottle preforms were subjected to six [...] Read more.

For sustainable development aligned with circular economy principles, the recycling of biopolymers such as polylactic acid (PLA) is of growing interest. In this study, the effect of primary recycling through repeated mechanical reprocessing was investigated. PLA water bottle preforms were subjected to six consecutive extrusion cycles, and changes in its molecular structure and physical properties were evaluated. Structural analysis revealed a progressive degradation, evidenced by a great reduction in the molar mass and increase in the melt flow index, attributed both to the chain scission derived from the thermal degradation and shear stresses of the extrusion process, and hydrolysis at the ester linkage of the polymer. Recycled samples exhibited a darkening of the color and a continuous decrease in thermal stability. After six reprocessing cycles, PLA crystallinity increased from 6.9 to 39.5%, the cold crystallization process disappeared, and molecular weight reduced by up to 40%. Barrier properties were highly affected after reprocessing and by the increase in relative humidity. Biodegradation tests revealed that crystallinity affected considerably the biodegradation rate of PLA. Although the molecular weight was considerably reduced during reprocessing, the biodegradation was slowed down. These findings provide insights into the limitations and potential of mechanically recycled PLA for future material applications. Full article

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

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46 pages, 29512 KB

Open AccessArticle

From Research Trend to Performance Prediction: Metaheuristic-Driven Machine Learning Optimization for Cement Pastes Containing Bio-Based Phase Change Materials

by Leifa Li, Wangwen Sun, Lauren Y. Gómez-Zamorano, Zhuangzhuang Liu, Wenzhen Zhang and Haoran Ma

Polymers 2025, 17(18), 2541; https://doi.org/10.3390/polym17182541 - 19 Sep 2025

Viewed by 529

Abstract

This study presents an integrated approach combining bibliometric analysis and machine learning to explore research trends and predict the performance of cement pastes containing bio-based phase change materials. A bibliometric review of 5928 articles from the Web of Science Core Collection was conducted [...] Read more.

This study presents an integrated approach combining bibliometric analysis and machine learning to explore research trends and predict the performance of cement pastes containing bio-based phase change materials. A bibliometric review of 5928 articles from the Web of Science Core Collection was conducted using CiteSpace (v.6.3.R1) to identify research hotspots. A dataset of 100 experimental samples was compiled, including nine input variables and three output properties identified as thermal conductivity (Tc), latent heat capacity (LH) and compressive strength (CS). Four machine learning algorithms (SVR, RF, XGBoost, and CatBoost) were optimized using five metaheuristic algorithms (GA, PSO, WOA, GWO, and FFA), resulting in 24 optimized hybrid models. Of all the models considered, CatBoost-WOA achieved the best overall performance, with R² values of 0.927, 0.955, and 0.944, and RMSEs of 0.0057 W/m·K, 1.84 J/g, and 2.91 MPa for Tc, LH, and CS. Additionally, SVR-GWO and XGBoost-WOA also showed strong generalization and low error dispersion. The developed models provide a transferable and data-driven modeling pipeline for predicting the coupled thermal and mechanical behavior of cement pastes containing bio-based phase change materials. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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20 pages, 2436 KB

Open AccessArticle

Thermal and Mechanical Performance of Maleic Anhidride/Benzoyl Peroxide-Modified PLA/PCL Biocomposites

by Aritz Unamuno Garay, Alexandra Llidó Barragán, Santiago Ferrandiz-Bou and Maria Dolores Samper

Polymers 2025, 17(18), 2540; https://doi.org/10.3390/polym17182540 - 19 Sep 2025

Viewed by 354

Abstract

This study investigated PLA/PCL blends modified with maleic anhydride (MA) via radical grafting using benzoyl peroxide (BPO) as an initiator. Different formulations with 5 and 10 wt.% of PLA-g-MA (containing 1, 3, and 5 wt.% MA) were prepared to evaluate their compatibilizing effect. [...] Read more.

This study investigated PLA/PCL blends modified with maleic anhydride (MA) via radical grafting using benzoyl peroxide (BPO) as an initiator. Different formulations with 5 and 10 wt.% of PLA-g-MA (containing 1, 3, and 5 wt.% MA) were prepared to evaluate their compatibilizing effect. Samples were characterized thermally, mechanically, and morphologically using DSC, TGA, FTIR, goniometry, SEM, and tensile, impact, and hardness tests. The results show that adding PCL significantly improves the ductility of PLA, though it reduces tensile strength and hardness. Grafting with MA partially improves phase compatibility, as seen by increased elongation at break and impact resistance, especially at intermediate MA concentrations (1–3%). However, higher MA contents lead to greater variability in thermal and mechanical results, likely due to heterogeneous phase dispersion. FTIR analysis detected residual BPO in some formulations, though below 0.1 phr. TGA indicated a slight improvement in thermal stability at 5 wt.% MA. Overall, the findings suggest that controlled use of MA as a compatibilizer enhances the balance of mechanical and thermal properties in PLA/PCL systems. Full article

(This article belongs to the Special Issue Biodegradable Polymer Composites, 2nd Edition)

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15 pages, 4276 KB

Open AccessArticle

Electrochemical Synthesis of Aminated Polyaniline/Multi-Walled Carbon Nanotube Composite for Selective Dopamine Detection in Artificial Urine

by Saengrawee Sriwichai and Pimmada Thongnoppakhun

Polymers 2025, 17(18), 2539; https://doi.org/10.3390/polym17182539 - 19 Sep 2025

Viewed by 457

Abstract

Monitoring dopamine (DA) has attracted increasing attention due to alterations in DA levels associated with brain disorders. In addition, the urinary DA concentration plays a significant role in the sympathoadrenal system. A decrease in DA can impair reward-seeking behavior and cognitive flexibility. Therefore, [...] Read more.

Monitoring dopamine (DA) has attracted increasing attention due to alterations in DA levels associated with brain disorders. In addition, the urinary DA concentration plays a significant role in the sympathoadrenal system. A decrease in DA can impair reward-seeking behavior and cognitive flexibility. Therefore, accurate and precise DA detection is necessary. In this study, a poly(3-aminobenzylamine)/functionalized multi-walled carbon nanotube (PABA/f-CNT) composite thin film was fabricated by electrochemical synthesis, or electropolymerization, of 3-aminobenzylamine (3-ABA) monomer and f-CNTs through cyclic voltammetry (CV) on a fluorine-doped tin oxide (FTO)-coated glass substrate, which also served as a working electrode for label-free DA detection in artificial urine. The formation of the film was confirmed by the obtained cyclic voltammogram, electrochemical impedance spectroscopy (EIS) plots, and scanning electron microscope (SEM) and transmission electron microscope (TEM) images. The chemical components of the films were analyzed using attenuated total reflection–Fourier transform infrared (ATR–FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). For label-free DA detection, various concentrations (50–1000 nM) of DA were determined in buffer solution through differential pulse voltammetry (DPV). The fabricated PABA/f-CNT film presented two linear ranges of 50–400 nM (R² = 0.9915) and 500–1000 nM (R² = 0.9443), with sensitivities of 1.97 and 0.95 µA·cm⁻²·µM⁻¹, respectively. The limit of detection (LOD) and the limit of quantity (LOQ) were 119.54 nM and 398.48 nM, respectively. In addition, the PABA/f-CNT film provided excellent selectivity against common interferents (ascorbic acid, uric acid, and glucose) with high stability, reproducibility, and repeatability. For potential future medical applications, DA detection was further performed in artificial urine, yielding a high percentage of recovery. Full article

(This article belongs to the Special Issue Development of Applications of Polymer-Based Sensors and Actuators)

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19 pages, 3852 KB

Open AccessArticle

Novel Egg White Protein–Chitin Nanocrystal Biocomposite Films with Enhanced Functional Properties

by Víctor Baquero-Aznar, Víctor Calvo, José Miguel González-Domínguez, Wolfgang K. Maser, Ana M. Benito, María Luisa Salvador and Jaime González-Buesa

Polymers 2025, 17(18), 2538; https://doi.org/10.3390/polym17182538 - 19 Sep 2025

Cited by 1 | Viewed by 600

Abstract

This study aims to develop egg white protein (EWP) biocomposite films reinforced with chitin nanocrystals (ChNCs, 1–5 wt.%) by compression molding to overcome the mechanical and barrier limitations of protein-based films for sustainable packaging. ChNC incorporation may modulate film microstructure, crystallinity, and thermal [...] Read more.

This study aims to develop egg white protein (EWP) biocomposite films reinforced with chitin nanocrystals (ChNCs, 1–5 wt.%) by compression molding to overcome the mechanical and barrier limitations of protein-based films for sustainable packaging. ChNC incorporation may modulate film microstructure, crystallinity, and thermal stability, thereby enhancing functional performance. Films were prepared by adding ChNCs either as aqueous suspensions or lyophilized powder, and their structural, thermal, mechanical, optical, and barrier properties were systematically evaluated. Scanning electron microscopy confirmed a more homogeneous dispersion of ChNCs when added as suspensions, while powder addition promoted partial aggregation. X-ray diffraction revealed increased crystallinity with ChNC reinforcement. Mechanical tests showed that films with 2 wt.% ChNCs in suspension exhibited the highest tensile strength, whereas those with 5 wt.% in powder form became stiffer but less extensible. Oxygen permeability was not significantly affected, while water vapor permeability decreased by up to 14.5% at 2 wt.% ChNCs incorporated as powder. Transparency and color remained largely unchanged by ChNC addition, except for a slight increase in yellowness. Overall, these findings demonstrate that the incorporation method and concentration of ChNCs play a crucial role in tailoring the physicochemical performance of EWP films. The results provide new insights into the design of EWP-based nanocomposites and support their potential as bio-derived materials for advanced food packaging applications. Full article

(This article belongs to the Special Issue Sustainable Polymers for Value Added and Functional Packaging)

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29 pages, 5126 KB

Open AccessArticle

Integrating Computational and Experimental Methods for the Rational Ecodesign and Synthesis of Functionalized Safe and Sustainable Biobased Oligoesters

by Federico Zappaterra, Anamaria Todea, Fioretta Asaro, Pasquale Fabio Alberto Ditalia, Chiara Danielli, Monia Renzi, Serena Anselmi and Lucia Gardossi

Polymers 2025, 17(18), 2537; https://doi.org/10.3390/polym17182537 - 19 Sep 2025

Viewed by 332

Abstract

A chemical platform for post-polymerization methods was developed, starting from the ecodesign and enzymatic synthesis of safe and sustainable bio-based polyesters containing discrete units of itaconic acid. This unsaturated bio-based monomer enables the covalent linkage of molecules that can impart desired properties such [...] Read more.

A chemical platform for post-polymerization methods was developed, starting from the ecodesign and enzymatic synthesis of safe and sustainable bio-based polyesters containing discrete units of itaconic acid. This unsaturated bio-based monomer enables the covalent linkage of molecules that can impart desired properties such as hydrophilicity, flexibility, permeability, or affinity for biological targets. Molecular descriptor-based computational methods, which are generally used for modeling the pharmacokinetic properties of drugs (ADME), were employed to predict in silico the hydrophobicity (LogP), permeability, and flexibility of virtual terpolymers composed of different polyols (1,4-butanediol, glycerol, 1,3-propanediol, and 1,2-ethanediol) with adipic acid and itaconic acid. Itaconic acid, with its reactive vinyl group, acts as a chemical platform for various post-polymerization functionalizations. Poly(glycerol adipate itaconate) was selected because of its higher hydrophilicity and synthetized via solvent-free enzymatic polycondensation at 50 °C to prevent the isomerization or crosslinking of itaconic acid. The ecotoxicity and marine biodegradability of the resulting oligoester were assessed experimentally in order to verify its compliance with safety and sustainability criteria. Finally, the viability of the covalent linkage of biomolecules via Michael addition to the vinyl pendant of the oligoesters was verified using four molecules bearing thiol and amine nucleophilic groups: N-acetylcysteine, N-Ac-Phe-ε-Lys-OtBu, Lys-Lys-Lys, and glucosamine. Full article

(This article belongs to the Special Issue Post-Functionalization of Polymers)

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18 pages, 10487 KB

Open AccessArticle

Design and Characterization of Durable Glass Fibre (GF)-Reinforced PLA and PEEK Biomaterials

by Asit Kumar Gain and Liangchi Zhang

Polymers 2025, 17(18), 2536; https://doi.org/10.3390/polym17182536 - 19 Sep 2025

Viewed by 423

Abstract

Poly(lactic acid) (PLA) and poly(ether-ether ketone) (PEEK) are widely recognized for their biocompatibility and processability in orthopaedic applications. However, PLA suffers from brittleness and limited thermal and mechanical stability, while PEEK, despite its better strength, does not fully replicate the mechanical and tribological [...] Read more.

Poly(lactic acid) (PLA) and poly(ether-ether ketone) (PEEK) are widely recognized for their biocompatibility and processability in orthopaedic applications. However, PLA suffers from brittleness and limited thermal and mechanical stability, while PEEK, despite its better strength, does not fully replicate the mechanical and tribological performance of natural bone. This study explores the enhancement of structural and tribological properties in PLA- and PEEK-based composites reinforced with short glass fibres (S-GF) via additive manufacturing. Microstructural analysis confirms uniform GF dispersion within both polymer matrices, with no evidence of agglomeration, fibre pull-out, or interfacial debonding, suggesting strong fibre–matrix adhesion. The incorporation of GF significantly improved mechanical performance: microhardness increased by 38.3% in PLA and 36.3% in PEEK composites, while tensile strength increased by 25.1% and 13.4%, respectively, compared to plain polymers. These enhancements are attributed to effective stress transfer enabled by uniform fibre distribution and strong interfacial bonding. Tribological tests further demonstrate enhanced wear resistance, reduce damage propagation, and improved surface integrity under micro-scratching. These findings highlight the potential of GF-reinforced PLA and PEEK composites as high-performance materials for load-bearing biomedical applications, offering a balanced combination of mechanical strength and wear resistance aligned with the functional requirements of bioimplants. Full article

(This article belongs to the Special Issue Additive Manufacturing of (Bio)Polymeric Materials, 2nd Edition)

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12 pages, 4877 KB

Open AccessArticle

Preparation of Concentrated PMMA Suspensions Stabilized by a Green Polysiloxane Surfactant

by Diana Borisova, Kirill Borisov, Aleksandra Kalinina, Aleksandra Bystrova, Inessa Gritskova and Aziz Muzafarov

Polymers 2025, 17(18), 2535; https://doi.org/10.3390/polym17182535 - 19 Sep 2025

Viewed by 423

Abstract

This study presents an approach to stabilizing suspension particles using novel eco-friendly hyperbranched organosilicon surfactants—poly(methyl ethoxysiloxane) with poly(ethylene glycol) groups (PMEOS-PEG). The surface-active properties of PMEOS-PEG polymers at the methyl methacrylate–water interface were thoroughly investigated. We demonstrate the successful preparation of concentrated, stable [...] Read more.

This study presents an approach to stabilizing suspension particles using novel eco-friendly hyperbranched organosilicon surfactants—poly(methyl ethoxysiloxane) with poly(ethylene glycol) groups (PMEOS-PEG). The surface-active properties of PMEOS-PEG polymers at the methyl methacrylate–water interface were thoroughly investigated. We demonstrate the successful preparation of concentrated, stable aqueous suspensions of poly(methyl methacrylate) with tunable particle sizes ranging from 370 nm to 840 nm. Full article

(This article belongs to the Section Polymer Chemistry)

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18 pages, 3359 KB

Open AccessArticle

Understanding the Effect of Graphene Nanoplatelet Size on the Mechanical and Thermal Properties of Fluoroelastomer-Based Composites

by Santiago Maldonado-Magnere, Mehrdad Yazdani-Pedram, Pablo Fuentealba, Andrónico Neira-Carrillo, Miguel A. Lopez-Manchado, Hector Hernandez-Villar, Allan Bascuñan-Heredia, Mohamed Dahrouch and Héctor Aguilar-Bolados

Polymers 2025, 17(18), 2534; https://doi.org/10.3390/polym17182534 - 19 Sep 2025

Viewed by 462

Abstract

This study presents a comprehensive evaluation of the behavior of fluoroelastomer (FKM) compounds reinforced with graphene nanoplatelets of various sizes such as 15 μm (GN15) and 5 μm (GN5). The study evaluates the mechanical, dynamic mechanical, thermal, wetting, and photothermal properties of the [...] Read more.

This study presents a comprehensive evaluation of the behavior of fluoroelastomer (FKM) compounds reinforced with graphene nanoplatelets of various sizes such as 15 μm (GN15) and 5 μm (GN5). The study evaluates the mechanical, dynamic mechanical, thermal, wetting, and photothermal properties of the compounds when irradiated with an 808 nm laser. The results demonstrate that the size of the graphene nanoplatelets significantly impacts the mechanical properties, with smaller sizes exhibiting a stronger reinforcing effect compared to larger nanoplatelets. Additionally, clear evidence of an influence on dynamic mechanical properties was observed, particularly through the broadening of the damping factor (tan δ) peak. This suggests modifications to the material’s viscoelastic behavior. Regarding the photothermal response, it was found that smaller nanoplatelets (GN5) dispersed in the rubber matrix allow higher temperatures to be reached and thermal equilibrium to be achieved more efficiently under irradiation. Overall, the results suggest that FKM compounds containing graphene nanoplatelets can attain high temperatures with low-energy infrared irradiation. This makes them promising materials for technological applications in extreme environments, such as the Arctic, high mountains, or space, where materials with controlled thermal responses and high mechanical performance are required. Full article

(This article belongs to the Topic Advances in Rubbers, Elastomers and Resins for Leading Edge Technologies)

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19 pages, 4689 KB

Open AccessArticle

Evaluation and Optimization of Thermoplastic Extrusion Parameters Influencing the Impact Resistance of Additively Manufactured Samples from PETG and Recycled PETG

by Dragos Gabriel Zisopol, Mihail Minescu and Dragos Valentin Iacob

Polymers 2025, 17(18), 2533; https://doi.org/10.3390/polym17182533 - 19 Sep 2025

Viewed by 423

Abstract

Given the widespread use of additive manufacturing technologies through plastic extrusion and the need to use recycled plastic materials, this paper presents the results of the study on the evaluation and optimization of the influence of theromoplastic extrusion parameters on the impact resistance [...] Read more.

Given the widespread use of additive manufacturing technologies through plastic extrusion and the need to use recycled plastic materials, this paper presents the results of the study on the evaluation and optimization of the influence of theromoplastic extrusion parameters on the impact resistance of additively manufactured samples from PETG and recycled PETG (rPETG) filament from the Everfil brand. In this context, 90 impact samples, 45 from PETG and 45 from rPETG, were additively manufactured by thermoplastic extrusion by the QIDI Q1 Pro printer, with the layer height deposited per pass L_h = 0.10/0.15/0.20 mm and the filling percentage I_d = 50/75/100%, which were subsequently subjected to impact testing by the HST XJJD-50T machine, using the 7.5J hammer and the impact speed of 2.9 m/s. In order to statistically evaluate the influence of the variable parameters of thermoplastic extrusion, layer height per pass (L_h) and filling percentage (I_d), on the impact strengths of additively manufactured PETG and rPETG samples, ANOVA and DOE analyses were performed using Minitab 20.3 software. Using the determined optimal parameters (L_h = 0.10 mm and I_d = 100%), impact strength values were obtained that were 210.87% higher than the impact strength values obtained from testing PETG samples. Considering the impact strength results obtained for the samples manufactured from rPETG and the fact that rPETG filament is 11% cheaper per kilogram than PETG filament, it can be concluded that the use of rPETG filament is a viable solution for the additive manufacturing of parts by thermoplastic extrusion. Full article

(This article belongs to the Collection Feature Papers in Polymer Processing and Engineering)

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Polymers, Volume 17, Issue 18 (September-2 2025) – 129 articles

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