Polymers

18 pages, 4043 KiB

Open AccessArticle

Numerical Simulation of Fatigue Damage in Cross-Ply CFRP Laminates: Exploring Frequency Dependence and Internal Heat Generation Effects

by Natsuko Kudo, M. J. Mohammad Fikry, Shinji Ogihara and Jun Koyanagi

Polymers 2025, 17(3), 432; https://doi.org/10.3390/polym17030432 - 6 Feb 2025

Viewed by 775

Abstract

A numerical simulation investigating the frequency dependence of fatigue damage progression in carbon fiber-reinforced plastics (CFRPs) is conducted in this study. The initiation and propagation of transverse cracks under varying fatigue test frequencies are successfully simulated, consistent with experiments, using an enhanced degradable [...] Read more.

A numerical simulation investigating the frequency dependence of fatigue damage progression in carbon fiber-reinforced plastics (CFRPs) is conducted in this study. The initiation and propagation of transverse cracks under varying fatigue test frequencies are successfully simulated, consistent with experiments, using an enhanced degradable Hashin failure model that was originally developed by the authors in 2022. The results obtained from the numerical simulation in the present study, which employs adjusted numerical values for the purpose of damage acceleration, indicate that the number of cycles required for the formation of three transverse cracks was 174 cycles at 0.1 Hz, 209 cycles at 1 Hz, and 165 cycles at 10 Hz. Based on these results, it is demonstrated that under high-frequency cyclic loading, internal heat generation caused by dissipated energy from mechanical deformation, attributed to the viscoelastic and/or plastic behavior of the material, exceeds thermal dissipation to the environment, leading to an increase in specimen temperature. Consequently, damage progression accelerates under high-frequency fatigue. In contrast, under low-frequency fatigue, viscoelastic dissipation becomes more pronounced, reducing the number of cycles required to reach a similar damage state. The rate of damage accumulation initially increases with test frequency but subsequently decreases. This observation underscores the importance of incorporating these findings into discussions on the fatigue damage of real structural components. Full article

(This article belongs to the Special Issue Mechanical and Dynamic Characteristics of Polymers and Polymer Composites)

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17 pages, 2789 KiB

Open AccessArticle

Effects of Degassing Treatment on the Dielectric Properties of XLPE Insulation Used in High-Voltage DC Power Cables

by Man Ding, Qingfeng Zheng, Jiahe Wang, Weifeng He, Chao Dai and Dingjun Wen

Polymers 2025, 17(3), 431; https://doi.org/10.3390/polym17030431 - 6 Feb 2025

Cited by 1 | Viewed by 926

Abstract

Cross-linked polyethylene power cables are widely used in high-voltage DC transmission lines, owing to their good dielectric and physical–chemical properties. However, the production process of XLPE involves cross-linking and degassing, in which the cross-linking process produces a variety of cross-linking by-products, and the [...] Read more.

Cross-linked polyethylene power cables are widely used in high-voltage DC transmission lines, owing to their good dielectric and physical–chemical properties. However, the production process of XLPE involves cross-linking and degassing, in which the cross-linking process produces a variety of cross-linking by-products, and the changes in the properties of the cable insulation caused by the degassing process are not well understood. XLPE samples were degassed at 90 °C for 7 and 14 days in this paper, and the main by-products were found to be α-methylstyrene, acetophenone, and cumyl alcohol, the contents of which all declined after the degassing treatment. The results show that the space charge density, the leakage current under a high electric field at different temperatures, and the breakdown strength of the XLPE samples all decreased after the degassing treatment. On the other hand, the XLPE sample after 7 days’ degassing had the lowest conductivity and the highest conductance activation, and the space charge density and the charge decay rate as well as the breakdown strength after 7 days’ degassing differed little from the 14-day treated sample, demonstrating that the 7-day degassing treatment at 90 °C would be enough to achieve superior performance. Full article

(This article belongs to the Special Issue Advanced Polymer Materials: Synthesis, Structure, and Properties)

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15 pages, 6869 KiB

Open AccessArticle

Study on the Space Charge Characteristics of Polypropylene Insulation Material Under a Polarity Reversal Electric Field

by Xinhua Dong, Guodong Bao and Wei Wang

Polymers 2025, 17(3), 430; https://doi.org/10.3390/polym17030430 - 6 Feb 2025

Viewed by 566

Abstract

High-voltage (HV) cables may experience voltage polarity reversal during power adjustment, leading to the accumulation of space charges inside the insulation material and causing distortion of the internal electric field. To characterize the effect of grafting modification on the insulation properties of polypropylene [...] Read more.

High-voltage (HV) cables may experience voltage polarity reversal during power adjustment, leading to the accumulation of space charges inside the insulation material and causing distortion of the internal electric field. To characterize the effect of grafting modification on the insulation properties of polypropylene (PP), various electrical properties were characterized. The results show that grafting modification can significantly improve the electrical properties of PP, with PPG-2 exhibiting the best electrical properties. Compared with PP, the breakdown strength of PPG-2 is increased by 39.27%, and the critical electric field is increased by 36.52%. Meanwhile, the charge accumulation inside the PPG-2 is extremely small after voltage polarity reversal. The mechanism of grafting modification to enhance the electrical properties of PP was explained by analyzing the trap characteristics of the samples. This indicates that grafting modification introduces a large number of deep traps within PP, suppressing the injection and migration of charge carriers. The presence of deep traps weakens the charge accumulation and electric field distortion at the interface. In this paper, the optimal monomer and content of grafted PP were determined, and the insulation properties of the cable under operating conditions were analyzed. The research results offer practical guidance for the development of high-performance grafted PP cable insulation materials and the reliability of cable operation. Full article

(This article belongs to the Special Issue Advanced Polymeric Materials for Electrical Insulation and High-Voltage Applications)

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13 pages, 1539 KiB

Open AccessArticle

Exploring the Catalytic Efficiency of Lithium Bis(trimethylsilyl)amide (LiHMDS) in Lactide Polymerization

by Almas Kiran, Achukee Chinedu Kingsley and Hassan Ahmed

Polymers 2025, 17(3), 429; https://doi.org/10.3390/polym17030429 - 6 Feb 2025

Viewed by 701

Abstract

The exploration of efficient catalysts for the ring-opening polymerization of cyclic esters has significant implications for the synthesis of biocompatible and biodegradable polymers. In this work, the simple catalyst lithium bis(trimethylsilyl)amide (LiHMDS) with high activity was explored in detail for the synthesis of [...] Read more.

The exploration of efficient catalysts for the ring-opening polymerization of cyclic esters has significant implications for the synthesis of biocompatible and biodegradable polymers. In this work, the simple catalyst lithium bis(trimethylsilyl)amide (LiHMDS) with high activity was explored in detail for the synthesis of polylactide (PLA). Using LiHMDS as the catalyst, various cyclic esters were polymerized to obtain diverse sustainable polyesters, such as poly(lactide), poly(δ-valerolactone), and poly(caprolactone), with controlled molecular weights and narrow molecular weight distributions. PLA synthesis was accomplished in just a few minutes at room temperature, contributing to the sustainable advancement of this polymer. Full article

(This article belongs to the Section Polymer Chemistry)

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22 pages, 4031 KiB

Open AccessArticle

Innovative Utilization of Citrus Sinensis Peel Hydrogels: Enhancing Soil Water Retention and Efficient Removal of Methylene Blue from Wastewater

by Bingqin Teng, Jun Wu, Yuan Zhong, Yinhua Wang, Decheng Qiao, Runqi Quan, Zhengqian Zhou, Liqun Cai, Peng Qi, Zhuzhu Luo and Xiaodong Zhang

Polymers 2025, 17(3), 428; https://doi.org/10.3390/polym17030428 - 6 Feb 2025

Cited by 1 | Viewed by 958

Abstract

In the context of increasing water scarcity and environmental pollution, this study investigates the synthesis and application of p(AA-Oco-AAm)-g-Citrus Sinensis Peel hydrogel (CSP hydrogel) to enhance soil water retention and remove organic dyes from wastewater. Hydrogels were prepared using a combination of acrylamide [...] Read more.

In the context of increasing water scarcity and environmental pollution, this study investigates the synthesis and application of p(AA-Oco-AAm)-g-Citrus Sinensis Peel hydrogel (CSP hydrogel) to enhance soil water retention and remove organic dyes from wastewater. Hydrogels were prepared using a combination of acrylamide and acrylic acid, with the incorporation of citrus peel as a natural resource. The water absorption capacity of the hydrogels was evaluated, achieving a maximum retention rate of 477 g/g, significantly improving the water-holding ability of various soil types. Additionally, the hydrogels demonstrated a strong affinity for methylene blue, with an equilibrium adsorption capacity reaching 2299.45 mg/g, indicating their effectiveness in wastewater treatment. Kinetic and isothermal adsorption models were applied to analyze the adsorption dynamics, revealing a superior fit to the Langmuir model. The hydrogels maintained structural integrity and reusability over multiple cycles, underscoring their potential for sustainable agricultural practices and environmental remediation. This research highlights the dual benefits of utilizing agricultural waste for the development of eco-friendly materials while addressing critical challenges in water management and pollution control. Full article

(This article belongs to the Section Polymer Networks and Gels)

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18 pages, 2197 KiB

Open AccessArticle

In Vitro Release Dynamics of Atorvastatin-Loaded Alginate Particles for Enhanced Periodontal Treatment

by Imke Hlawa, Thomas Reske, Oleksandra Chabanovska, Malte Scholz, Praveen Vasudevan, Stefan Oschatz, Niels Grabow and Hermann Lang

Polymers 2025, 17(3), 427; https://doi.org/10.3390/polym17030427 - 6 Feb 2025

Viewed by 870

Abstract

Periodontitis is a chronic inflammatory condition of the periodontium, which often leads to tooth loss. Recently, statins have emerged as potent anti-inflammatory agents with pleiotropic effects that can potentially outperform conventional periodontal treatments. However, the clinical application of statins is limited by the [...] Read more.

Periodontitis is a chronic inflammatory condition of the periodontium, which often leads to tooth loss. Recently, statins have emerged as potent anti-inflammatory agents with pleiotropic effects that can potentially outperform conventional periodontal treatments. However, the clinical application of statins is limited by the lack of suitable drug carriers that fit the periodontal region and provide a controlled local drug release. In this study, we address the critical gap in localized periodontal drug delivery and introduce an ultrasound-assisted technique to encapsulate atorvastatin within alginate microparticles (10–400 µm in diameter)—a simple, scalable, and biocompatible solution. While ultrasound is widely used in polymer synthesis, its application in alginate polymerization remains underexplored. To mimic physiological conditions, particles were incubated in artificial saliva at 37 °C, with drug release being analyzed via high-performance liquid chromatography. A methylcellulose-based hydrogel served as a conventional reference product. Results revealed that alginate particles exhibited at least a 10-fold increase in mean dissolution time compared to the methylcellulose gel, indicating superior stability. Increasing atorvastatin concentration extended the time interval needed for 50% of the drug to be released (t_50%) from 1 h to 11 h, maintaining the overall drug diffusion level for several days. Further analysis showed that covalent cross-linking of alginate with divinyl sulfone significantly delayed the initial drug release by 3 h (p < 0.05) due to the additional molecular stabilization. These findings underscore the utility of ultrasonic atomization for the processing of alginate-based formulations. Given the ease of production, biocompatibility, and small size, successfully fabricated alginate particles represent a promising carrier for delivery of statins or other related drugs in clinical dentistry. Full article

(This article belongs to the Special Issue Polymers & Polymer Composites for Dental Applications)

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15 pages, 8817 KiB

Open AccessArticle

Effects of Process Parameters on the Mechanical Properties and Microstructure of Additively Manufactured Carbon Black Particles-Reinforced Thermoplastic Polyurethane Composite Samples

by Fatima Hira, Muhammad Asif, Hammad Ullah, Imran Khan, Ghulam Hussain, Muhammad Amir and Mohammed Alkahtani

Polymers 2025, 17(3), 426; https://doi.org/10.3390/polym17030426 - 6 Feb 2025

Cited by 1 | Viewed by 742

Abstract

Additive manufacturing (AM) techniques make fabricating complex designs, prototypes, and end-user products possible. Conductive polymer composites find applications in flexible electronics, sensor fabrication, and electrical circuits. In this study, thermoplastic polyurethane (TPU)-based conductive polymer composite samples were fabricated via fused filament fabrication (FFF). [...] Read more.

Additive manufacturing (AM) techniques make fabricating complex designs, prototypes, and end-user products possible. Conductive polymer composites find applications in flexible electronics, sensor fabrication, and electrical circuits. In this study, thermoplastic polyurethane (TPU)-based conductive polymer composite samples were fabricated via fused filament fabrication (FFF). The effects of three important process parameters, including infill density (ID), layer thickness (LT), and fan speed (FS), on various mechanical properties (tensile and compressive properties) were investigated. It was observed that all the considered process parameters affect the mechanical properties, and they are significant parameters, as per the analysis of variance (ANOVA). From scanning electron microscopy (SEM) and optical microscopy, various combinations of parameters such as low ID, high LT, and high FS resulted in the formation of defects such as voids, cracks, and warping, which resulted in low mechanical properties. Finally, process parameter optimization was performed, resulting in a conductive polymer composite with the best possible combination of mechanical properties at high ID, low LT, and medium FS. Full article

(This article belongs to the Special Issue Design and Sustainability: Polymer Composites via Additive Manufacturing)

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15 pages, 3317 KiB

Open AccessArticle

Effects of Guar Gum and Sodium Benzoate on the Properties and Hydrophilicity of Silk Fibroin Hydrogels

by Ansaya Thonpho, Yodthong Baimark, Suchai Tanisood and Prasong Srihanam

Polymers 2025, 17(3), 425; https://doi.org/10.3390/polym17030425 - 6 Feb 2025

Viewed by 772

Abstract

Silk fibroin (SF)–based hydrogels were prepared by the simple evaporation method. The outcomes of SF–based hydrogels were assessed for consideration in terms of practical and convenient use. Guar gum (GG) and sodium benzoate (SB) are blending reagents to the SF solution and are [...] Read more.

Silk fibroin (SF)–based hydrogels were prepared by the simple evaporation method. The outcomes of SF–based hydrogels were assessed for consideration in terms of practical and convenient use. Guar gum (GG) and sodium benzoate (SB) are blending reagents to the SF solution and are poured into the petri dish to make the hydrogels. After leaving the mixture solution for three days to solidify, all SF–based hydrogels were peeled off and characterized. The SF–blend guar gum (SF–GG) and SF–GG–blend sodium benzoate (SF–GG–SB) could be constructed, but in different textures and levels of transparency. The SB affected the solid texture and resulted in a higher water contact angle (WCA) value of the prepared SF hydrogel than of the SF–GG. The results from Fourier transform infrared spectroscopy (FTIR) indicated all the main functional groups of substances that were contained in the blending hydrogels. Moreover, some interactions between the functional groups were also detected. A thermogravimetric analyzer (TGA) was used to determine the hydrogel decomposition as a function of temperature. The DTG thermograms, which exhibit the maximum decomposition temperature, revealed that the interaction forces between blending substances and SF, as well as their structure, are the reason for the thermal stability of the SF–based hydrogels. SF–GG–SB hydrogels have higher tensile strength than the SF–GG hydrogels. In conclusion, the appearance, texture, hydrophilicity, thermal stability, and tensile strength of the SF–based hydrogels were affected by the types and concentrations of the blending substances. This suggests that the SF–based hydrogel properties could be designed and adjusted to attain desirable textures for fitting target applications. Full article

(This article belongs to the Special Issue Advances in Synthesis, Testing, and Applications of Natural and Synthetic Polymer Hydrogels)

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14 pages, 5236 KiB

Open AccessArticle

High-Efficiency and Low-Resistance Melt-Blown/Electrospun PLA Composites for Air Filtration

by Yongmei Guo, Mingzhu Wu, Xiaojian Ye, Shengchao Wei, Luming Huang and Hailing Guo

Polymers 2025, 17(3), 424; https://doi.org/10.3390/polym17030424 - 6 Feb 2025

Viewed by 927

Abstract

Biodegradable polylactic acid (PLA) was used to fabricate nonwoven fabrics via the melt blowing process, followed by electrospinning to deposit a nanofiber membrane. This composite process yielded PLA melt-blown/electrospun composite materials with excellent filtration performance. The effects of the solution concentration and spinning [...] Read more.

Biodegradable polylactic acid (PLA) was used to fabricate nonwoven fabrics via the melt blowing process, followed by electrospinning to deposit a nanofiber membrane. This composite process yielded PLA melt-blown/electrospun composite materials with excellent filtration performance. The effects of the solution concentration and spinning duration on the composite structure and material performance were investigated. The optimal composite was produced using a 10 wt.% PLA spinning solution prepared with a solvent mixture of dichloromethane (DCM) and N, N-dimethylformamide (DMF) in a 75/25 weight ratio. The process parameters included a spinning duration of 5 h, 18 kV voltage, 1.5 mL/h flow rate, and 12 cm collection distance. The resulting composite achieved a filtration efficiency of 98.7%, a pressure drop of 142 Pa, an average pore size of 5 μm, and a contact angle of 138.7°. These results provided optimal process parameters for preparing PLA melt-blown/electrospun composite filtration materials. This study highlights the potential of hydrophobic PLA composites with high filtration efficiency and low air resistance as environmentally friendly alternatives to traditional non-degradable filtration materials. Full article

(This article belongs to the Special Issue Fabrication and Application of Biopolymer-Based Advanced Functional Materials, 2nd Edition)

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24 pages, 12348 KiB

Open AccessArticle

Copper(II)-Complexed Polyethylenimine-Entrapped Gold Nanoparticles Enable Targeted CT/MR Imaging and Chemodynamic Therapy of Tumors

by Lingxiu He, Na Liu, Risong Pan and Jingyi Zhu

Polymers 2025, 17(3), 423; https://doi.org/10.3390/polym17030423 - 6 Feb 2025

Viewed by 680

Abstract

Transition-metal ion copper(II) (Cu(II)) has drawn increasing attention as a small-molecular cancer theranostic agent. However, delivering a sufficient dosage of Cu(II) to the tumor site and integrating multiple imaging modalities to achieve precise and effective cancer theranostics remains a critical challenge. Herein, an [...] Read more.

Transition-metal ion copper(II) (Cu(II)) has drawn increasing attention as a small-molecular cancer theranostic agent. However, delivering a sufficient dosage of Cu(II) to the tumor site and integrating multiple imaging modalities to achieve precise and effective cancer theranostics remains a critical challenge. Herein, an emerging Cu(II)-based nanocomposite has been synthesized for targeted tumor computed tomography (CT)/magnetic resonance (MR) dual-mode imaging and chemodynamic therapy (CDT). Briefly, 2-picolinic acid (PA-COOH), polyethylene glycol (PEG)-linked folic acid (FA), and fluorescein isothiocyanate (FI) were sequentially conjugated with polyethylenimine (PEI.NH₂) and then in situ fabrication of gold nanoparticles (Au NPs) occurred within the PEI.NH₂ internal cavity. After acetylation of PEI.NH₂ terminal amines and Cu(II) complexation, the Cu(II)-based nanocomposites FA-Au/Cu(II) PENPs with a mean diameter of 2.87 nm were generated. The synthesized FA-Au/Cu(II) PENPs showed favorable stability of colloidal dispersion, sustainable Cu(II) release properties in a pH-dependent manner, and Fenton-like catalytic activity specifically. With the FA-mediated targeting pathway, FA-Au/Cu(II) PENPs can specifically accumulate in cancer cells with high expression of FA receptors. Meanwhile, the complementary CT/MR dual-mode imaging in vitro and in vivo can be afforded by FA-Au/Cu(II) PENPs based on the excellent X-ray attenuation properties of Au NPs and the applicable r₁ relaxivity (0.7378 mM⁻¹s⁻¹) of Cu(II). Notably, the Cu(II)-mediated CDT mechanism enables FA-Au/Cu(II) PENPs to elicit the generation of toxic hydroxyl radicals (·OH), depletion of glutathione (GSH), promotion of lipid peroxidation (LPO), and induction of cancer cell apoptosis in vitro, and further demonstrates remarkable anti-tumor efficacy in a xenograft tumor model. With the illustrated targeted theranostic capacity of FA-Au/Cu(II) PENPs towards tumors, this Cu(II)-based nanocomposite paradigm inspires the construction of advanced theranostic nanoplatforms incorporating alternative transition metal ions. Full article

(This article belongs to the Special Issue Advanced Polymeric Materials for Medical Applications)

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12 pages, 3795 KiB

Open AccessArticle

Mechanochemically Synthesized PEG-OTs as a Green Corrosion Inhibitor

by Qiannian Wang, Yuan Sang, Jiang Yang and Hailing Liu

Polymers 2025, 17(3), 422; https://doi.org/10.3390/polym17030422 - 5 Feb 2025

Cited by 1 | Viewed by 559

Abstract

Polymer corrosion inhibitors are reported to form dense films on carbon steel surfaces, and their thermostability enables survival in harsh downhole environments. In this paper, PEG-OTs was synthesized by mechanochemistry using ball mill by grafting tosyl on PEG. Using this solvent-free green chemistry, [...] Read more.

Polymer corrosion inhibitors are reported to form dense films on carbon steel surfaces, and their thermostability enables survival in harsh downhole environments. In this paper, PEG-OTs was synthesized by mechanochemistry using ball mill by grafting tosyl on PEG. Using this solvent-free green chemistry, non-toxic PEG and PEG-OTs with various molecular weights (600, 2000, and 10,000 g/mol) were prepared and used as corrosion inhibitors. The corrosion inhibition performance of 5 × 10⁻³ mol/L inhibitors on Q235 carbon steel in 0.5 M HCl solution was investigated using static weight-loss, electrochemical impedance spectroscopy, polarization curves, SEM, and contact angle measurements. The results show that, after modification, PEG-OTs has an elevated corrosion inhibition effect compared to PEG. A maximum of 90% corrosion inhibition efficiency was achieved using static weight-loss. The morphology study shows that a dense film formed to protect carbon steel. Thanks to their polymeric structure, a higher molecular weight leads to better corrosion inhibition. Full article

(This article belongs to the Section Polymer Applications)

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29 pages, 12339 KiB

Open AccessArticle

Numerical Modeling and Optimization Design of Embedded Rubber Waterstops in Tunnel Lining

by Xuan Fan, Hailin Wang, Chaoran Xie, Mingfeng Lei and Chenjie Gong

Polymers 2025, 17(3), 421; https://doi.org/10.3390/polym17030421 - 5 Feb 2025

Viewed by 611

Abstract

Tunnel water leakage is a common issue. Embedded rubber waterstops are crucial in ensuring the waterproofing performance of mountain tunnels. The deformation performance of a rubber waterstop directly impacts its effectiveness, with structural parameters playing a key role. This study employs numerical simulation [...] Read more.

Tunnel water leakage is a common issue. Embedded rubber waterstops are crucial in ensuring the waterproofing performance of mountain tunnels. The deformation performance of a rubber waterstop directly impacts its effectiveness, with structural parameters playing a key role. This study employs numerical simulation methods to quantitatively assess the impact of structural parameters—such as the central hole, ribs, and flanges—on the deformation performance of waterstops. The parametric analysis reveals significant variations in how different structural components affect the deformation performance, as indicated by the defined deformation stress influence rate. Specifically, the deformation performance of the embedded waterstop under tensile, compression, and settlement deformations shows a correlation with factors such as the ratio of the central hole opening rate to thickness and the inner and outer diameters. Additionally, an optimization analysis, taking both economic and performance factors into account, was conducted on 16 types of waterstops with different central hole parameters, from which the optimal waterstop was selected. This research provides a scientific basis for enhancing the deformation performance of waterstops and optimizing their structure. Full article

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

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17 pages, 3514 KiB

Open AccessArticle

A Numerical Study on the Drug Release Process of Biodegradable Polymer Drug-Loaded Vascular Stents

by Shiyong Li, Yunbo Wei and Hongxia Li

Polymers 2025, 17(3), 420; https://doi.org/10.3390/polym17030420 - 5 Feb 2025

Viewed by 731

Abstract

Biodegradable polymer drug-loaded vascular stents are a typical and promising application in the field of invasive interventional therapy. The drug release process of drug-loaded vascular stents, as well as the drug concentration in the vascular wall and its change process, will affect the [...] Read more.

Biodegradable polymer drug-loaded vascular stents are a typical and promising application in the field of invasive interventional therapy. The drug release process of drug-loaded vascular stents, as well as the drug concentration in the vascular wall and its change process, will affect the therapeutic effect of vascular stents on vascular stenosis. As a drug carrier, the degradation properties of the polymer will affect the drug release process. In this study, the drug release process from the biodegradable polymer stent and the drug delivery process in vascular lumens and intravascular walls were studied by using 3D finite element method, with the effect of the biodegradation behavior of polymer on the drug release process being considered. The effects of the initial drug concentration, stent geometry, and polymer degradation rate on the drug release and delivery process were investigated. The results showed that the initial drug concentration and the thickness of the polymer stent significantly affected the drug concentration in the middle layer of the vessel wall, but the initial drug concentration had no effect on the drug release duration. The degradation of the polymer causes its porosity to change with time, which affects the drug diffusion in polymer, and further affects the drug concentration in the vessel wall. The three-dimensional structure of the stent can affect the blood flow in the blood vessel, resulting in drug deposition near the struts, especially near the intersection of the support struts and the bridge struts. Full article

(This article belongs to the Special Issue Biodegradable Polymers in Sustainable and Biomedical Applications)

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19 pages, 20476 KiB

Open AccessArticle

Enhancing Cassava Starch Bioplastics with Vismia guianensis Alcoholic Extract: Characterization with Potential Applications

by Josiel F. Santos, Crystian Willian C. Silva, Barbara P. G. Silva, Pedro H. Britto-Costa, Cleidilane S. Costa, Larissa Otubo, Artur W. Carbonari and Gabriel A. Cabrera-Pasca

Polymers 2025, 17(3), 419; https://doi.org/10.3390/polym17030419 - 5 Feb 2025

Viewed by 984

Abstract

This work investigates the incorporation of Vismia guianensis alcoholic extract (EAVG) into cassava starch, with the aim of improving its bioplastic properties. Cassava starch was dissolved into distilled water and doped with 0.2%, 0.5%, and 1.0% EAVG under a temperature controlled at the [...] Read more.

This work investigates the incorporation of Vismia guianensis alcoholic extract (EAVG) into cassava starch, with the aim of improving its bioplastic properties. Cassava starch was dissolved into distilled water and doped with 0.2%, 0.5%, and 1.0% EAVG under a temperature controlled at the gelatinization point (∼70 °C) and then cast to form bioplastics. The resulting samples were characterized via attenuated total reflectance/Fourier transform infrared spectroscopy (ATR/FTIR), thermogravimetric and differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), atomic force microscopy (AFM), and mechanical essays, providing insights into chemical composition, thermal stability, crystallinity, surface morphology, and mechanical properties. The results demonstrated that EAVG played an effective role, enhancing the flexibility and stability of the bioplastic with potential use in biomedical applications. Moreover, the results also showed significant improvements in mechanical and thermal properties, suggesting that EAVG is a valuable addition to bioplastics. Therefore, EAVG presents a pathway for advancing bioplastics with enhanced mechanical, thermal, and functional characteristics, with the potential for further advancements in these fields. Full article

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

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12 pages, 4883 KiB

Open AccessArticle

Three-Dimensional Ordering of Nematic Liquid Crystals with Azimuth and Tilt Controlled by Patterned Photoalignment and Selective Polymer Stabilization

by Marta Kajkowska, Miłosz Sławomir Chychłowski, Michał Ptaszek and Sławomir Ertman

Polymers 2025, 17(3), 418; https://doi.org/10.3390/polym17030418 - 5 Feb 2025

Viewed by 636

Abstract

In this paper, we present a novel approach for advanced, three-dimensional patterned ordering of nematic liquid crystals. Our method allows for simultaneous control of azimuth and tilt of molecules by using a two-step process based on patterned photoalignment (used to define azimuth) followed [...] Read more.

In this paper, we present a novel approach for advanced, three-dimensional patterned ordering of nematic liquid crystals. Our method allows for simultaneous control of azimuth and tilt of molecules by using a two-step process based on patterned photoalignment (used to define azimuth) followed by selective polymer stabilization of molecules reorientated with an electric field (used to define tilt). We demonstrate that those two subsequent processes, realized with high-resolution patterned illumination with UV light, allow us to obtain multiple microdomains with independently controlled tilt and azimuth. It opens possibilities to create complex three-dimensional distributions of director within a single liquid crystal cell, which is impossible with any other technique so far. Moreover, although the polymer-stabilization process is used, it is still possible to retune the tilt of the molecules; however, the electric field intensity needed for tuning is slightly higher than in the non-polymerized areas of the sample. Full article

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

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16 pages, 4206 KiB

Open AccessArticle

Nano-Polymers as Cas9 Inhibitors

by Oksana Chepurna, Avradip Chatterjee, Yuanqing Li, Hong Ding, Ramachandran Murali, Keith L. Black and Tao Sun

Polymers 2025, 17(3), 417; https://doi.org/10.3390/polym17030417 - 5 Feb 2025

Viewed by 735

Abstract

Despite wide applications of CRISPR/Cas9 technology, effective approaches for CRISPR delivery with functional control are limited. In an attempt to develop a nanoscale CRSIPR/Cas9 delivery platform, we discovered that several biocompatible polymers, including polymalic acid (PMLA), polyglutamic acid (PGA), and polyaspartic acid (PLD), [...] Read more.

Despite wide applications of CRISPR/Cas9 technology, effective approaches for CRISPR delivery with functional control are limited. In an attempt to develop a nanoscale CRSIPR/Cas9 delivery platform, we discovered that several biocompatible polymers, including polymalic acid (PMLA), polyglutamic acid (PGA), and polyaspartic acid (PLD), when conjugated with a trileucine (LLL) moiety, can effectively inhibit Cas9 nuclease function. The Cas9 inhibition by those polymers is dose-dependent, with varying efficiency to achieve 100% inhibition. Further biophysical studies revealed that PMLA-LLL directly binds the Cas9 protein, resulting in a substantial decrease in Cas9/sgRNA binding affinity. Transmission electron microscopy and molecular docking were performed to provide a possible binding mechanism for PMLA-LLL to interact with Cas9. This work identified a new class of Cas9 inhibitor in nano-polymer form. These biodegradable polymers may serve as novel Cas9 delivery vehicles with a potential to enhance the precision of Cas9-mediated gene editing. Full article

(This article belongs to the Special Issue Advanced Biodegradable Polymers for Drug Delivery)

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16 pages, 5593 KiB

Open AccessArticle

Geometric Accuracy and Dimensional Precision in 3D Printing-Based Gear Manufacturing: A Study on Interchangeability and Forming Precision

by Xiaofeng Wei, Siwei Zhang, Lingli Sun, Xinyu Zhao, Mengchen Sun, Run Yu, Xingwen Zhou and Yuhang Li

Polymers 2025, 17(3), 416; https://doi.org/10.3390/polym17030416 - 4 Feb 2025

Viewed by 861

Abstract

This paper investigates the geometric interchangeability and dimensional precision of parts fabricated using Fused Deposition Modeling (FDM), with a focus on gear manufacturing. By employing a substrate and two spur gears as test components, critical process parameters, including layer thickness, extrusion speed, and [...] Read more.

This paper investigates the geometric interchangeability and dimensional precision of parts fabricated using Fused Deposition Modeling (FDM), with a focus on gear manufacturing. By employing a substrate and two spur gears as test components, critical process parameters, including layer thickness, extrusion speed, and print temperature, were optimized to achieve enhanced accuracy. Geometric and dimensional tolerances such as straightness, roundness, and surface roughness were systematically evaluated using advanced metrological techniques. The results indicate that larger components demonstrate higher precision, with deviations for large and pinion gears ranging between −0.045 and 0.060 mm, and −0.150 and 0.078 mm, respectively. Analysis reveals that the anisotropic nature of the FDM process and thermal shrinkage significantly impact accuracy, particularly in smaller features. Residual stress analysis reveals that smaller components formed via FDM exhibit higher stress concentrations and dimensional deviations due to voids and uneven thermal contraction, whereas larger components and flat substrates achieve better stress distribution and precision. The findings suggest that reducing material shrinkage coefficients and optimizing process parameters can enhance part quality, achieving dimensional tolerances within ±0.1 mm and geometric consistency suitable for practical applications. This research highlights the potential of FDM for precision manufacturing and provides insights into improving its performance for high-demand industrial applications. Full article

(This article belongs to the Special Issue Polymer Materials for Application in Additive Manufacturing)

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31 pages, 10252 KiB

Open AccessArticle

Numerical Simulation of Rotational Speed Sinusoidal Pulsation for Enhancing Polymer Processing Based on Smoothed Particle Hydrodynamics

by Tianlei Liu, Hesheng Liu, Tianwen Dong, Jiamei Lai, Wei Yu, Zhong Yu and Huiwen Yu

Polymers 2025, 17(3), 415; https://doi.org/10.3390/polym17030415 - 4 Feb 2025

Viewed by 712

Abstract

Vibration-assisted methods are playing a more and more important role in processing polymers for twin screw extruders (TSEs) in order to satisfy the increasing requirements for polymetric products in various applications, but existing vibrating technologies are usually restricted in school laboratories and industrial [...] Read more.

Vibration-assisted methods are playing a more and more important role in processing polymers for twin screw extruders (TSEs) in order to satisfy the increasing requirements for polymetric products in various applications, but existing vibrating technologies are usually restricted in school laboratories and industrial research rooms because of their drawbacks. The purpose of this study is to design a novel vibration method for TSEs. Numerical simulation was performed based on a meshless method, namely smoothed particle hydrodynamics (SPH). The velocity distribution, particle distribution, and pressure of particles in a co-rotating twin screw component in the conveying zone of a TSE are investigated in detail to recover the influence of the rotational speed excitation on the flow properties of both fully filled and partially filled states. The results show that cases under superimposed excitation can produce a more variable physical effect, thus enhancing and weakening the velocity field and the pressure field alternately. And on the whole, that effect could improve the particle distribution in according cases. These findings can lay a solid foundation for further study on the development and application of superimposed excitation technology in the polymer processing of TSEs. Full article

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

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16 pages, 5968 KiB

Open AccessArticle

Polyethylene Polyamine-Modified Chitosan Aerogels: Enhanced CO₂ Adsorbents with Lamellar Porous Structures

by Hui Ming, Haoxin Jiang, Ruiyang Zheng, Mei Wu, Hongying Li, Zhengxin Li, Xudong Zhang, Zihao Yuan and Ziyue Wang

Polymers 2025, 17(3), 414; https://doi.org/10.3390/polym17030414 - 4 Feb 2025

Viewed by 1197

Abstract

Due to the continuous growth of global carbon dioxide emissions, the development of cost-effective carbon dioxide capture technology has attracted extensive attention. Amino-modified chitosan aerogels with lamellar porous structures are good candidates as carbon dioxide adsorbents because of their degradable properties and low [...] Read more.

Due to the continuous growth of global carbon dioxide emissions, the development of cost-effective carbon dioxide capture technology has attracted extensive attention. Amino-modified chitosan aerogels with lamellar porous structures are good candidates as carbon dioxide adsorbents because of their degradable properties and low energy consumption. Polyethylene polyamine-modified chitosan aerogels (PEPA-CSs) were prepared through a process of crosslinking and freeze-drying using a chitosan solution, polyethylene polyamine (PEPA), and epichlorohydrin (ECH) as raw materials. The amino group of PEPA was proven to be successfully grafted on the chitosan surface by FITR and XPS. The SEM and TEM analysis showed a rich three-dimensional porous structure and a good rigidity and bearing capacity of the PEPA-CS. The adsorption capacity was significantly increased by PEPA grafting with a maximum value of 1.59 mmol/g at 25 °C and 1 bar through both physical and chemical interactions, which indicates a potential for broad application prospects in industrial CO₂-capture applications. Full article

(This article belongs to the Section Polymer Networks and Gels)

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14 pages, 3644 KiB

Open AccessArticle

Preparation and Hg⁰ Removal Performance of MIL-101(Cr)-Derived Carbon Matrix Composites

by Haotian Nie, Zikuo Li, Xikai Zhang, Jinchao Wen, Youxiang Feng, Yue Yu and Li Jia

Polymers 2025, 17(3), 413; https://doi.org/10.3390/polym17030413 - 4 Feb 2025

Viewed by 616

Abstract

The temperature at which pollutants are treated varies across different industrial processes. To address the high cost of raw materials for MOFs and the low efficiency of Hg⁰ removal in low-temperature environments, a series of MIL-101(Cr)-derived carbon matrix composite materials were prepared [...] Read more.

The temperature at which pollutants are treated varies across different industrial processes. To address the high cost of raw materials for MOFs and the low efficiency of Hg⁰ removal in low-temperature environments, a series of MIL-101(Cr)-derived carbon matrix composite materials were prepared by combining MIL-101(Cr) with biomass and multiple metals. These materials were synthesized through a sol-gel method followed by carbonization. This study investigates the effects of composite ratios and adsorption temperatures on Hg⁰ removal, utilizing XRD, BET, and other characterization techniques to elucidate the mercury-removal mechanism of the PDC-MIL composite materials. The results indicate that MIL101(Cr) significantly influences the formation of the gel skeleton. When the composite ratio of MIL-101(Cr) to biomass is 1:1, the material exhibits an optimal pore structure, leading to high Hg⁰ removal efficiency over a wide temperature range. The removal of Hg⁰ by these composite materials involves both physical adsorption and chemisorption. Low temperatures favor physical adsorption, while high temperatures promote chemisorption. The sol-gel composite method facilitates cross-linking polymerization between MOFs and SiO₂, enabling better pore structure connectivity with biomass and MOFs, thereby optimizing the poor pore structure observed after pyrolysis. Consequently, the improved pore structure enhances physical adsorption at low temperatures, mitigates desorption at high temperatures, and increases the contact probability of Hg⁰ with active sites within the pores, significantly improving the mercury-removal ability of the material across a broad temperature range. Full article

(This article belongs to the Special Issue Reduction of Pollution and Carbon Emissions, Functional Polymeric Materials for Adsorption and Catalysis)

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17 pages, 3938 KiB

Open AccessReview

Inulin as a Biopolymer; Chemical Structure, Anticancer Effects, Nutraceutical Potential and Industrial Applications: A Comprehensive Review

by Isaac Karimi, Mahnaz Ghowsi, Layth Jasim Mohammed, Zohreh Haidari, Kosar Nazari and Helgi B. Schiöth

Polymers 2025, 17(3), 412; https://doi.org/10.3390/polym17030412 - 4 Feb 2025

Viewed by 1123

Abstract

Inulin is a versatile biopolymer that is non-digestible in the upper alimentary tract and acts as a bifidogenic prebiotic which selectively promotes gut health and modulates gut–organ axes through short-chain fatty acids and possibly yet-to-be-known interactions. Inulin usage as a fiber ingredient in [...] Read more.

Inulin is a versatile biopolymer that is non-digestible in the upper alimentary tract and acts as a bifidogenic prebiotic which selectively promotes gut health and modulates gut–organ axes through short-chain fatty acids and possibly yet-to-be-known interactions. Inulin usage as a fiber ingredient in food has been approved by the FDA since June 2018 and it is predicted that the universal inulin market demand will skyrocket in the near future because of its novel applications in health and diseases. This comprehensive review outlines the known applications of inulin in various disciplines ranging from medicine to industry, covering its benefits in gut health and diseases, metabolism, drug delivery, therapeutic pharmacology, nutrition, and the prebiotics industry. Furthermore, this review acknowledges the attention of researchers to knowledge gaps regarding the usages of inulin as a key modulator in the gut–organ axes. Full article

(This article belongs to the Special Issue Advances in Sustainable Polymeric Materials, 3rd Edition)

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27 pages, 5828 KiB

Open AccessArticle

Flexural Behavior of Thin Concrete Slabs Reinforced with Surface Embossed Grid-Type Carbon-Fiber Composites

by Kyung-Min Kim, Sung-Woo Park and Kyung-Jae Min

Polymers 2025, 17(3), 411; https://doi.org/10.3390/polym17030411 - 4 Feb 2025

Viewed by 526

Abstract

Fiber-reinforced polymers (FRPs) are being increasingly used to replace rebars as reinforcements for concrete. In this study, the flexural behavior of one-way concrete slabs reinforced with a grid-type carbon FRP (CFRP) (carbon grid), in the form of strands with embossed surfaces, was experimentally [...] Read more.

Fiber-reinforced polymers (FRPs) are being increasingly used to replace rebars as reinforcements for concrete. In this study, the flexural behavior of one-way concrete slabs reinforced with a grid-type carbon FRP (CFRP) (carbon grid), in the form of strands with embossed surfaces, was experimentally investigated. The experimental variables included the effective depth, number of carbon grid layers, and concrete compressive strength. The results exhibit that the surface embossing of the CFRP strands effectively improves their bonding with concrete based on the crack formation pattern. Concrete specimens reinforced with carbon grids exhibited an increased maximum load and stiffness as the effective depth, number of carbon grid layers, and concrete compressive strength increased. Among the experimental variables, the effective depth exhibited the greatest influence on the flexural behavior of the carbon-grid-reinforced concrete specimen. Furthermore, the ratios of the experimental to calculated flexural strength values for all carbon-grid-reinforced concrete specimens ranged from 0.74 to 1.22. Based on the results, a trilinear load–deflection curve was proposed to simulate the flexural behavior of carbon-grid-reinforced concrete members, considering the bond property between the concrete and the carbon grid. The proposed trilinear load–deflection curve reasonably simulated the flexural behavior of the specimens reinforced with carbon grids. Full article

(This article belongs to the Special Issue Fiber Reinforced Polymers Applications as Reinforcement of Concrete Structures—Design Aspects, Tests and Analysis, 2nd Edition)

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33 pages, 24144 KiB

Open AccessArticle

Printability and Performance Metrics of New-Generation Multifunctional PMMA/Antibacterial Blend Nanocomposites in MEX Additive Manufacturing

by Markos Petousis, Nektarios K. Nasikas, Vassilis Papadakis, Ioannis Valsamos, Katerina Gkagkanatsiou, Nikolaos Mountakis, Apostolos Argyros, Evgenia Dimitriou, Nikolaos Michailidis and Nectarios Vidakis

Polymers 2025, 17(3), 410; https://doi.org/10.3390/polym17030410 - 4 Feb 2025

Viewed by 750

Abstract

Poly(methyl methacrylate) (PMMA) is a thermoplastic widely utilized in civilian-, defense-, and medicine-related applications. Therefore, inducing antibacterial properties is an additional asset when infection control is prioritized. To counter this, PMMA was mixed, for the first time, with antibacterial agents (antibacterial blend nanopowder, [...] Read more.

Poly(methyl methacrylate) (PMMA) is a thermoplastic widely utilized in civilian-, defense-, and medicine-related applications. Therefore, inducing antibacterial properties is an additional asset when infection control is prioritized. To counter this, PMMA was mixed, for the first time, with antibacterial agents (antibacterial blend nanopowder, AP) to curb bacterial proliferation and therefore reduce the chances of infection. The reinforcing efficacy of the blend in PMMA was also assessed. Nanocomposites were developed with various nanopowder concentrations for 3D printing material extrusion (MEX). PMMA/AP nanocomposites were evaluated for their mechanical and rheological properties, thermal stability, morphological, structural, and chemical characteristics, and bacterial resistance (against Staphylococcus aureus and Escherichia coli (E. Coli) using the well diffusion method). The effect on quality metrics, such as the geometrical accuracy and pores of the 3D-printed structure was examined with micro-computed tomography. The modified PMMA had improved properties, such as increased tensile (~20% increase at 2 wt.%) and flexural strength (~10.8% at 4 wt.%), while also having strong antibacterial properties against Staphylococcus aureus and mild antibacterial properties against E. Coli. Such improvements add to the expanding portfolio of biomaterials, such as their use in the demanding defense sector and the medical field. Full article

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

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16 pages, 15835 KiB

Open AccessArticle

Research on Laser Direct Transmission Welding of Transparent Polystyrene and Polycarbonate Based on Laser Surface Modification

by Kehui Zhai, Fuhao Yang, Qiyan Gu, Yu Lin, Minqiu Liu, Deqin Ouyang, Yewang Chen, Ying Zhang, Qitao Lue and Shuangchen Ruan

Polymers 2025, 17(3), 409; https://doi.org/10.3390/polym17030409 - 4 Feb 2025

Viewed by 739

Abstract

The conventional near-infrared laser transmission welding (LTW) process for joining dissimilar transparent polymers is limited by the need to incorporate optical absorbents, which compromises joint performance and raises biocompatibility concerns. To address these issues, this study proposed a surface modification technique using femtosecond [...] Read more.

The conventional near-infrared laser transmission welding (LTW) process for joining dissimilar transparent polymers is limited by the need to incorporate optical absorbents, which compromises joint performance and raises biocompatibility concerns. To address these issues, this study proposed a surface modification technique using femtosecond laser ablation prior to the welding process. Experiments involved 520 nm femtosecond laser ablation of transparent polymers, followed by LTW of dissimilar transparent polymers using an 808 nm laser, with subsequent characterization and mechanical property evaluations. A maximum joint strength of 13.65 MPa was achieved. A comprehensive investigation was conducted into the physical and chemical mechanisms through which laser ablation improved the welding performance of dissimilar transparent polymers. The results demonstrated that laser ablation generated microstructures that serve as substitutes for optical absorbents while also facilitating the formation of numerous oxygen-containing functional groups. These enhancements improve miscibility and bonding performance between dissimilar polymers, enabling absorbent-free welding between ablated polycarbonate (PC) and polystyrene (PS). This work confirms both the feasibility and potential application of this process for direct LTW of dissimilar transparent polymers. Full article

(This article belongs to the Section Polymer Applications)

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24 pages, 2155 KiB

Open AccessReview

Polymers Derived from Agro-Industrial Waste in the Development of Bioactive Films in Food

by Carlos Culqui-Arce, Diner Mori-Mestanza, Armstrong B. Fernández-Jeri, Robert J. Cruzalegui, Roberto Carlos Mori Zabarburú, Alex J. Vergara, Ilse S. Cayo-Colca, Juliana Guimarães da Silva, Nayara Macêdo Peixoto Araujo, Efraín M. Castro-Alayo and César R. Balcázar-Zumaeta

Polymers 2025, 17(3), 408; https://doi.org/10.3390/polym17030408 - 4 Feb 2025

Cited by 1 | Viewed by 1507

Abstract

This review explores the potential of biopolymers as sustainable alternatives to conventional plastics in food packaging. Biopolymers derived from plant or animal sources are crucial in extending food shelf life, minimizing degradation, and protecting against oxidative and microbial agents. Their physical and chemical [...] Read more.

This review explores the potential of biopolymers as sustainable alternatives to conventional plastics in food packaging. Biopolymers derived from plant or animal sources are crucial in extending food shelf life, minimizing degradation, and protecting against oxidative and microbial agents. Their physical and chemical properties, influenced by the raw materials used, determine their suitability for specific applications. Biopolymers have been successfully used in fruits, vegetables, meats, and dairy products, offering antimicrobial and antioxidant benefits. Consequently, they represent a functional and eco-friendly solution for the packaging industry, contributing to sustainability while maintaining product quality. Full article

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

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23 pages, 9639 KiB

Open AccessArticle

Enhancing Carbon Fiber-Reinforced Polymers’ Performance and Reparability Through Core–Shell Rubber Modification and Patch Repair Techniques

by Dionisis Semitekolos, Sofia Terzopoulou and Costas Charitidis

Polymers 2025, 17(3), 407; https://doi.org/10.3390/polym17030407 - 3 Feb 2025

Viewed by 992

Abstract

Carbon fiber-reinforced polymers (CFRPs) are widely used in high-performance applications, but their inherent brittleness and susceptibility to impact damage remain critical challenges. This study investigated the effect of core–shell rubber (CSR) particles as impact modifiers on the mechanical properties of CFRPs and evaluated [...] Read more.

Carbon fiber-reinforced polymers (CFRPs) are widely used in high-performance applications, but their inherent brittleness and susceptibility to impact damage remain critical challenges. This study investigated the effect of core–shell rubber (CSR) particles as impact modifiers on the mechanical properties of CFRPs and evaluated patch repair techniques for damaged CFRP panels. Mechanical tests, including flexural, tensile, short-beam, fracture toughness, and impact tests, were conducted on reference and CSR-modified specimens to assess their structural performance. The CSR-modified samples demonstrated significant improvements in energy absorption and fracture toughness, with a 50% increase in impact strength and up to 181% improvement in absorbed energy during Mode I fracture testing. However, slight reductions in flexural and tensile strengths were observed due to the softening effect of CSR particles. Fracture surface analysis revealed distinct failure mechanisms, with Scanning Electron Microscopy imaging showing consistent fiber pull-out behavior in tensile and flexural tests, but more stable delamination propagation in CSR-modified specimens during short-beam shear tests. Patch repair effectiveness was assessed through drop-weight impact tests on damaged panels repaired with patches containing CSRs of two thicknesses. Patches of equal thickness to the damaged panel successfully restored structural integrity and enhanced energy absorption by 37% compared with the reference samples, while thinner patches (as a suggestion to reduce production costs) failed to withstand impact loads effectively. Non-destructive testing (NDT) via ultrasonic C-scans confirmed reduced delamination and damage depth in CSR-modified repaired panels, validating the toughening effect of CSR particles. These findings demonstrate the potential of CSR-modified resins to improve CFRPs’ performance and provide effective repair solutions for extending the service life of damaged composite structures, rendering them especially suitable for applications demanding high damage tolerance and durability, including aerospace structures, automotive body panels, and energy-absorbing crash components. Full article

(This article belongs to the Special Issue Mechanical Behaviour of Polymeric-Based Systems Used in Engineering Applications)

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20 pages, 5162 KiB

Open AccessArticle

Sustainable Reinforcement of Silicone Rubber: Comparative Analysis of Biosilica from Rice Husk and Conventional Silica

by Hyeon Woo Jeong, Kyoung Tae Park, Su Min Oh, Sang Eun Shim and Yingjie Qian

Polymers 2025, 17(3), 406; https://doi.org/10.3390/polym17030406 - 3 Feb 2025

Viewed by 1061

Abstract

The objective of this study is to compare rice husk-derived silica (biosilica) synthesized via an environmentally friendly method with conventional silica (Zeosil 175) for reinforcing the mechanical properties of silicone rubber. The silanol group content of Zeosil 175 (9.45 OH/nm²) is [...] Read more.

The objective of this study is to compare rice husk-derived silica (biosilica) synthesized via an environmentally friendly method with conventional silica (Zeosil 175) for reinforcing the mechanical properties of silicone rubber. The silanol group content of Zeosil 175 (9.45 OH/nm²) is higher than that of biosilica (7.07 OH/nm²), whereas the specific surface area of biosilica (159.52 m²/g) exceeds that of Zeosil 175 (144.90 m²/g). Silicone rubber specimens containing two types of silica nanoparticles were prepared at loading levels of 5, 10, 15, 20, 25, and 30 parts per hundred rubber to evaluate their mechanical properties and characteristics. Results indicate that silicone rubber filled with biosilica shows comparable tensile strength to Zeosil 175 at low filler contents, which can be attributed to its higher specific surface area. However, at higher loading levels, the mechanical properties are somewhat diminished due to the Payne effect and filler agglomeration resulting from the larger particle size of biosilica. These experimental findings offer insights into the potential utilization of rice husk-derived biosilica as an alternative to conventional silica in enhancing the properties of silicone rubber alongside the findings of the mechanical analysis. Full article

(This article belongs to the Special Issue Reinforced Rubber Composites: Synthesis and Application)

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16 pages, 1213 KiB

Open AccessReview

Polysaccharides: The Sweet and Bitter Impacts on Cardiovascular Risk

by Grzegorz Kalisz and Joanna Popiolek-Kalisz

Polymers 2025, 17(3), 405; https://doi.org/10.3390/polym17030405 - 3 Feb 2025

Cited by 1 | Viewed by 1064

Abstract

Cardiovascular risk is a clinical factor that represents the probability of developing cardiovascular diseases (CVDs). This risk is shaped by non-modifiable and modifiable factors, including dietary patterns, which are the main lifestyle factor influencing CVD. Dietary polysaccharides, integral to nutrition, have varying effects [...] Read more.

Cardiovascular risk is a clinical factor that represents the probability of developing cardiovascular diseases (CVDs). This risk is shaped by non-modifiable and modifiable factors, including dietary patterns, which are the main lifestyle factor influencing CVD. Dietary polysaccharides, integral to nutrition, have varying effects on cardiovascular health depending on their type and source. They include starches, non-starch polysaccharides, and prebiotic fibers, categorized further into soluble and insoluble fibers. Soluble fibers, found in oats, legumes, and fruits, dissolve in water, forming gels that help lower serum cholesterol and modulate blood glucose levels. Insoluble fibers, present in whole grains and vegetables, aid in bowel regularity. The cardiovascular benefits of polysaccharides are linked to their ability to bind bile acids, reducing cholesterol levels, and the production of short-chain fatty acids by gut microbiota, which have anti-inflammatory properties. However, not all polysaccharides are beneficial; refined starches can lead to adverse metabolic effects, and chitosan to mixed effects on gut microbiota. This review examines the dualistic nature of polysaccharides, highlighting their beneficial roles in reducing cardiovascular risk factors and the potential adverse effects of specific types. Full article

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

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16 pages, 3098 KiB

Open AccessArticle

Testing Protocols and Procedures for Undertaking Fire Resistance Tests on Concrete Structures Incorporating Fiber-Reinforced Polymers

by Venkatesh Kodur, M. Z. Naser and Hee Sun Kim

Polymers 2025, 17(3), 404; https://doi.org/10.3390/polym17030404 - 3 Feb 2025

Viewed by 751

Abstract

Fiber-reinforced polymers (FRPs) are often incorporated as internal (primary) reinforcement in new concrete constructions or as external (secondary) reinforcement in retrofitting and strengthening of existing concrete structures. Under fire conditions, the response of FRP-incorporated concrete structures are altered due to the presence of [...] Read more.

Fiber-reinforced polymers (FRPs) are often incorporated as internal (primary) reinforcement in new concrete constructions or as external (secondary) reinforcement in retrofitting and strengthening of existing concrete structures. Under fire conditions, the response of FRP-incorporated concrete structures are altered due to the presence of FRPs; thus, their fire performance is different from that of concrete structures with conventional metallic reinforcement. However, the fire resistance of these FRP-incorporated structural members continues to be evaluated through standard fire resistance tests, which are similar to conventional steel and concrete structural members. Despite the complexity of this testing approach and its drawbacks, standard fire testing remains a cornerstone in evaluating FRP-incorporated concrete structural members. Thus, this paper sheds more light on the fire testing procedure and discusses the distinctive factors that differentiate the fire performance of FRP-incorporated concrete structures from that of conventional concrete structures and the need for additional provisions to test such structures. To address the current shortcomings, a set of additional testing protocols and procedures for undertaking fire resistance tests on FRP-incorporated concrete structural members are presented. The performance criteria to be applied to evaluate the failure of FRP–RC structural members under fire conditions are discussed. Full article

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

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21 pages, 24481 KiB

Open AccessArticle

Cold-Drawn Wood-Filled Polybutylene Succinate Macro-Fibers as a Reinforcing Material for Concrete

by Jonas Herz, Verena Schusser, Dirk Muscat and Nicole Strübbe

Polymers 2025, 17(3), 403; https://doi.org/10.3390/polym17030403 - 3 Feb 2025

Viewed by 757

Abstract

The corrosive behavior of steel reinforcements causes issues in the concrete industry. To overcome this issue, alternative noncorrosive reinforcements such as polymer fibers could be used. However, as environmental protection becomes more important, sustainability must also be considered in the solution. An alternative [...] Read more.

The corrosive behavior of steel reinforcements causes issues in the concrete industry. To overcome this issue, alternative noncorrosive reinforcements such as polymer fibers could be used. However, as environmental protection becomes more important, sustainability must also be considered in the solution. An alternative to polymers based on raw oil is bio-based polymers. This study investigates the suitability of polymer fibers produced from polybutylene succinate together with cellulose and wood fillers as concrete reinforcements. Different mixtures of polybutylene succinate, cellulose, and wood fillers were created, and fibers were produced using a multiple drawing process. The fibers were tested using tensile tests, a single-fiber pull-out test, contact angle measurements, reflected light microscopy, density measurements, and thermogravimetric analysis. The fillers were shown to decrease the mechanical properties as the particle size and filler amount increased, resulting in a reduction in Young’s modulus and tensile strength of 55% and 70%, respectively, while adhesion to concrete increased with particle size from 0.31 ± 0.02 N/mm² without filler to 0.90 ± 0.10 N/mm² for the best-performing material combination. Reflected light microscopy images show changes in the fiber surface before and after pull-out. The fiber density decreased from 1.26 ± 0.05 g/cm³ to 0.91 ± 0.04 g/cm³ with an increasing filler amount and particle size for a compound with 10 weight percent of wood filler 1. The fiber thermal stability decreased slightly with the addition of filler. The greatest effect was a reduction in the temperature to ≈58 °C at 1% weight loss when 10 weight percent of wood was added. This study proves the possibility of using bio-based materials as concrete reinforcements. Full article

(This article belongs to the Section Polymer Fibers)

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