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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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19 pages, 6080 KiB  
Review
Current Status and Future Trends for Modification Technology of Flame Retardant Nylon 66
by Bingtao Feng, Senlong Yu, Hengxue Xiang, Lili Li and Meifang Zhu
Polymers 2025, 17(8), 1074; https://doi.org/10.3390/polym17081074 - 16 Apr 2025
Viewed by 179
Abstract
Nylon 66 (PA66) has been widely used in automotive, electronics, textiles and other fields due to its excellent mechanical properties, chemical corrosion resistance and thermal stability. However, the fire hazard caused by its flammability severely limits its further application in high–end and high–risk [...] Read more.
Nylon 66 (PA66) has been widely used in automotive, electronics, textiles and other fields due to its excellent mechanical properties, chemical corrosion resistance and thermal stability. However, the fire hazard caused by its flammability severely limits its further application in high–end and high–risk fields. Therefore, improving the flame retardancy of PA66 to enhance its safety has become the focus of current research. This review aims to better understand the research status and development trends of flame retardant PA66. Firstly, the combustion process and flame retardant mechanism of PA66 were described. Secondly, the latest research progress of flame retardant PA66 was comprehensively reviewed, including blending, copolymerization and post–finishing flame retardant modification methods. Meanwhile, the research status of blending flame retardant PA66 was emphatically introduced, and the advantages and disadvantages of different additive flame retardants were analyzed. Finally, the future development direction of flame retardant PA66 is proposed, which provides an important reference for its follow-up study. Full article
(This article belongs to the Special Issue Polymer Manufacturing Processes)
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30 pages, 1614 KiB  
Review
Hydrogel-Based Systems as Smart Food Packaging: A Review
by Beata Niemczyk-Soczynska and Paweł Łukasz Sajkiewicz
Polymers 2025, 17(8), 1005; https://doi.org/10.3390/polym17081005 - 8 Apr 2025
Viewed by 198
Abstract
In recent years, non-degradable petroleum-based polymer packaging has generated serious disposal, pollution, and ecological issues. The application of biodegradable food packaging for common purposes could overcome these problems. Bio-based hydrogel films are interesting materials as potential alternatives to non-biodegradable commercial food packaging due [...] Read more.
In recent years, non-degradable petroleum-based polymer packaging has generated serious disposal, pollution, and ecological issues. The application of biodegradable food packaging for common purposes could overcome these problems. Bio-based hydrogel films are interesting materials as potential alternatives to non-biodegradable commercial food packaging due to biodegradability, biocompatibility, ease of processability, low cost of production, and the absorption ability of food exudates. The rising need to provide additional functionality for food packaging has led scientists to design approaches extending the shelf life of food products by incorporating antimicrobial and antioxidant agents and sensing the accurate moment of food spoilage. In this review, we thoroughly discuss recent hydrogel-based film applications such as active, intelligent packaging, as well as a combination of these approaches. We highlight their potential as food packaging but also indicate the drawbacks, especially poor barrier and mechanical properties, that need to be improved in the future. We emphasize discussions on the mechanical properties of currently studied hydrogels and compare them with current commercial food packaging. Finally, the future directions of these types of approaches are described. Full article
(This article belongs to the Special Issue Development of Bio-Based Materials: Synthesis, Characterization, and Applications, 3rd Edition)
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22 pages, 5025 KiB  
Article
Biodegradable Polymer Composites Based on Poly(butylene succinate) Copolyesters and Wood Flour
by Agnieszka Kozłowska, Krzysztof Gorący and Miroslawa El Fray
Polymers 2025, 17(7), 883; https://doi.org/10.3390/polym17070883 - 26 Mar 2025
Viewed by 241
Abstract
This study investigates the biodegradation behavior of poly(butylene succinate) (PBS) copolyesters containing dilinoleic acid (DLA) co-monomeric units and wood flour (WF) as a filler. PBS-DLA is a segmented thermoplastic elastomer (TPE), where the soft amorphous phase is formed by DLA ester segments, while [...] Read more.
This study investigates the biodegradation behavior of poly(butylene succinate) (PBS) copolyesters containing dilinoleic acid (DLA) co-monomeric units and wood flour (WF) as a filler. PBS-DLA is a segmented thermoplastic elastomer (TPE), where the soft amorphous phase is formed by DLA ester segments, while the hard phase consists of crystallizable PBS domains. Wood–plastic composites (WPCs) were prepared with WF at weight fractions of 10%, 20%, 30%, and 40% wt. and analyzed in terms of surface morphology, chemical structure, mechanical performance, and thermal stability before and after biodegradation in soil conditions. The results of microscopic analysis confirmed that the PBS-DLA copolymer and its composites undergo surface biodegradation as manifested by increased surface roughness and microcrack formation, particularly in composites with a higher WF content. ATR FT-IR spectroscopy indicated oxidation and hydrolysis, supporting the hypothesis of progressive surface erosion. Mechanical tests showed a decline in tensile strength and elongation at break, with the most pronounced changes in composites containing 20% WF. Thermal analysis (DSC, DMTA, and TGA) confirmed that the PBS-DLA copolymer retains its thermoplastic elastomeric behavior after a 3-month biodegradation experiment. The storage modulus (E′) remained stable, while only minor variations in melting and crystallization temperatures were observed. These findings reinforce the hypothesis of surface erosion rather than a bulk degradation mechanism. Given their biodegradability and retained thermoplastic behavior, WPC composites based on PBS-DLA copolyester could be promising for eco-friendly applications where controlled degradation is desirable, such as in packaging, agriculture, or biodegradable consumer goods. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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46 pages, 7489 KiB  
Review
Environmental Impact of Textile Materials: Challenges in Fiber–Dye Chemistry and Implication of Microbial Biodegradation
by Arvind Negi
Polymers 2025, 17(7), 871; https://doi.org/10.3390/polym17070871 - 24 Mar 2025
Viewed by 461
Abstract
Synthetic and natural fibers are widely used in the textile industry. Natural fibers include cellulose-based materials like cotton, and regenerated fibers like viscose as well as protein-based fibers such as silk and wool. Synthetic fibers, on the other hand, include PET and polyamides [...] Read more.
Synthetic and natural fibers are widely used in the textile industry. Natural fibers include cellulose-based materials like cotton, and regenerated fibers like viscose as well as protein-based fibers such as silk and wool. Synthetic fibers, on the other hand, include PET and polyamides (like nylon). Due to significant differences in their chemistry, distinct dyeing processes are required, each generating specific waste. For example, cellulose fibers exhibit chemical inertness toward dyes, necessitating chemical auxiliaries that contribute to wastewater contamination, whereas synthetic fibers are a major source of non-biodegradable microplastic emissions. Addressing the environmental impact of fiber processing requires a deep molecular-level understanding to enable informed decision-making. This manuscript emphasizes potential solutions, particularly through the biodegradation of textile materials and related chemical waste, aligning with the United Nations Sustainable Development Goal 6, which promotes clean water and sanitation. For instance, cost-effective methods using enzymes or microbes can aid in processing the fibers and their associated dyeing solutions while also addressing textile wastewater, which contains high concentrations of unreacted dyes, salts, and other highly water-soluble pollutants. This paper covers different aspects of fiber chemistry, dyeing, degradation mechanisms, and the chemical waste produced by the textile industry, while highlighting microbial-based strategies for waste mitigation. The integration of microbes not only offers a solution for managing large volumes of textile waste but also paves the way for sustainable technologies. Full article
(This article belongs to the Special Issue Reactive and Functional Biopolymers)
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42 pages, 4134 KiB  
Review
Solvent-Based Recycling as a Waste Management Strategy for Fibre-Reinforced Polymers: Current State of the Art
by Matthew J. Keith, Bushra Al-Duri, Tom O. McDonald and Gary A. Leeke
Polymers 2025, 17(7), 843; https://doi.org/10.3390/polym17070843 - 21 Mar 2025
Viewed by 329
Abstract
The growing use of fibre-reinforced polymers (FRPs) is driving a demand for the development of sustainable end-of-life strategies. Solvolysis, a chemical recycling method using solvents to decompose the polymer matrix, has emerged as a promising approach for reclaiming both fibres and organic compounds [...] Read more.
The growing use of fibre-reinforced polymers (FRPs) is driving a demand for the development of sustainable end-of-life strategies. Solvolysis, a chemical recycling method using solvents to decompose the polymer matrix, has emerged as a promising approach for reclaiming both fibres and organic compounds from FRP waste. This work provides a comprehensive overview of solvolysis techniques by discussing the environmental benefits and economic opportunities of this technology, summarising the process conditions, and evaluating the characteristics of the recovered products. The economic viability of solvolysis lies in recovering high-value components; predominantly carbon fibres from CFRPs and organic products from GFRPs, which are suitable for reuse or as a feedstock for new composites. Solvolysis can operate under low temperature and pressure (LTP) or high temperature and pressure (HTP) conditions. The choice of solvent, catalyst, reaction time, and temperature is crucial to achieving high resin decomposition while preserving fibre properties. To achieve an economically viable and environmentally beneficial process, it will be essential to optimise these parameters. A key challenge is maintaining the strength and surface properties of the recovered fibres, as degradation in their performance can limit their suitability for high-performance applications. The implication of this is that, without careful consideration of the recycling process, FRPs cannot be fully circular. They will be continuously downgraded into low-value applications and ultimately incinerated or landfilled. This review further explores the diversity of organic products obtained, which can range from monomers to oligomers to complex mixtures. Efficient separation and upgrading techniques, such as distillation and liquid–liquid extraction, are essential to maximise the value of the recovered organics. These additional processing steps are likely to result in greater financial and resource costs within a commercial recycling system. This review concludes with a summary of commercial solvent-based recycling ventures and an outlook on future research directions, which includes the need to develop processes capable of recovering high-value, long carbon fibres. Successful development of such a process would represent a step-change in the value proposition of a carbon fibre recycling industry. Full article
(This article belongs to the Special Issue New Polymer Fibers: Production and Applications)
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16 pages, 4497 KiB  
Article
Experimental Investigation on the Application of Polymer Agents in Offshore Sandstone Reservoirs: Optimization Design for Enhanced Oil Recovery
by Yanyue Li, Changlong Liu, Yaqian Zhang, Baoqing Xue, Jinlong Lv, Chuanhui Miao, Yiqiang Li and Zheyu Liu
Polymers 2025, 17(5), 673; https://doi.org/10.3390/polym17050673 - 2 Mar 2025
Viewed by 551
Abstract
The conventional polymer gel has high initial viscosity and short gelation time, making it difficult to meet the requirements of deep profile control in offshore reservoirs with large well spacing and strong heterogeneity. This paper evaluates the performance and core plugging capacity of [...] Read more.
The conventional polymer gel has high initial viscosity and short gelation time, making it difficult to meet the requirements of deep profile control in offshore reservoirs with large well spacing and strong heterogeneity. This paper evaluates the performance and core plugging capacity of novel functional polymer gels and microspheres to determine the applicability of core permeability ranges. On the heterogeneous core designed based on the reservoir characteristics of Block B oilfield, optimization was conducted separately for the formulation, dosage, and slug combinations of the polymer gel/microsphere. Finally, oil displacement experiments using polymer and microsphere combinations were conducted on vertically and planar heterogeneous cores to simulate reservoir development effects. The experimental results show the novel functional polymer gel exhibits slow gelation with high gel strength, with viscosity rapidly increasing four days after aging, ultimately reaching a gel strength of 74,500 mPa·s. The novel functional polymer gel and polymer microsphere can effectively plug cores with permeabilities below 6000 mD and 2000 mD, respectively. For heterogeneous cores with an average permeability of 1000 mD, the optimal polymer microsphere has a concentration of 4000 mg/L and a slug size of 0.3 PV; for heterogeneous cores with an average permeability of 4000 mD, the optimal functional polymer gel has a concentration of 7500 mg/L and a slug size of 0.1 PV. In simulations of vertically and planarly heterogeneous reservoirs, the application of polymer agent increases the oil recovery factor by 53% and 38.7% compared to water flooding. This realizes the gradual and full utilization of layers with high, medium, and low permeability. Full article
(This article belongs to the Special Issue New Studies of Polymer Surfaces and Interfaces: 2nd Edition)
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37 pages, 1657 KiB  
Review
Regulatory Frameworks and State-of-the-Art Decontamination Technologies for Recycled Polystyrene for Food Contact Applications
by Javiera Sepúlveda-Carter, José L. Moreno de Castro, Laura Marín, Paula Baños, Marcos Sánchez Rodríguez and Marina P. Arrieta
Polymers 2025, 17(5), 658; https://doi.org/10.3390/polym17050658 - 28 Feb 2025
Viewed by 629
Abstract
Recycling post-consumer plastics for food contact applications is crucial for the circular economy; however, it presents challenges due to potential contamination and regulatory requirements. This review outlines the current European and U.S. legislation governing recycled plastics in food contact materials (FCM). The European [...] Read more.
Recycling post-consumer plastics for food contact applications is crucial for the circular economy; however, it presents challenges due to potential contamination and regulatory requirements. This review outlines the current European and U.S. legislation governing recycled plastics in food contact materials (FCM). The European Food Safety Authority (EFSA) mandates the evaluation and authorization of recycling processes. This includes examining input/output flows, prioritizing the use of previously authorized FCM, and assessing decontamination efficiency through material-specific challenge tests. Additionally, it evaluates new installations intended to apply approved decontamination technologies. In contrast, the voluntary submission to the U.S. Food and Drug Administration (FDA) provides guidelines with general advice on methodologies and recommended parameters and challenge tests. Applications to the EFSA for non-PET materials, such as HDPE, PP, and PS, are reviewed, highlighting the challenges of each material. Recycled PS, with its lower diffusivity compared to polyolefins shows promise for food packaging, with potential as a next material approved for use in the European Union. Decontamination technologies for post-consumer PS are explored, including super-cleaning processes, solvent extraction, and industrial methods. The review emphasizes the need for multidisciplinary collaboration to address the uncertainties around potential contaminants and ensure the safety of recycled plastics for food contact applications. Full article
(This article belongs to the Special Issue Recycling of Plastic and Rubber Wastes, 2nd Edition)
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94 pages, 13734 KiB  
Review
Advancing Textile Waste Recycling: Challenges and Opportunities Across Polymer and Non-Polymer Fiber Types
by Mehrdad Seifali Abbas-Abadi, Brecht Tomme, Bahman Goshayeshi, Oleksii Mynko, Yihan Wang, Sangram Roy, Rohit Kumar, Bhargav Baruah, Karen De Clerck, Steven De Meester, Dagmar R. D’hooge and Kevin M. Van Geem
Polymers 2025, 17(5), 628; https://doi.org/10.3390/polym17050628 - 26 Feb 2025
Cited by 2 | Viewed by 2031
Abstract
The growing environmental impact of textile waste, fueled by the rapid rise in global fiber production, underscores the urgent need for sustainable end-of-life solutions. This review explores cutting-edge pathways for textile waste management, spotlighting innovations that reduce reliance on incineration and landfilling while [...] Read more.
The growing environmental impact of textile waste, fueled by the rapid rise in global fiber production, underscores the urgent need for sustainable end-of-life solutions. This review explores cutting-edge pathways for textile waste management, spotlighting innovations that reduce reliance on incineration and landfilling while driving material circularity. It highlights advancements in collection, sorting, and pretreatment technologies, as well as both established and emerging recycling methods. Smart collection systems utilizing tags and sensors show great promise in streamlining logistics by automating pick-up routes and transactions. For sorting, automated technologies like near-infrared and hyperspectral imaging lead the way in accurate and scalable fiber separation. Automated disassembly techniques are effective at removing problematic elements, though other pretreatments, such as color and finish removal, still need to be customized for specific waste streams. Mechanical fiber recycling is ideal for textiles with strong mechanical properties but has limitations, particularly with blended fabrics, and cannot be repeated endlessly. Polymer recycling—through melting or dissolving waste polymers—produces higher-quality recycled materials but comes with high energy and solvent demands. Chemical recycling, especially solvolysis and pyrolysis, excels at breaking down synthetic polymers like polyester, with the potential to yield virgin-quality monomers. Meanwhile, biological methods, though still in their infancy, show promise for recycling natural fibers like cotton and wool. When other methods are not viable, gasification can be used to convert waste into synthesis gas. The review concludes that the future of sustainable textile recycling hinges on integrating automated sorting systems and advancing solvent-based and chemical recycling technologies. These innovations, supported by eco-design principles, progressive policies, and industry collaboration, are essential to building a resilient, circular textile economy. Full article
(This article belongs to the Section Circular and Green Sustainable Polymer Science)
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31 pages, 11807 KiB  
Article
Experimental and Theoretical Investigation into the Thermal Conductivity and Heating-Softening Bending of Glass-Fiber-Reinforced Polypropylene Rebars
by Mingxue Xu, Anni Wang and Xiaogang Liu
Polymers 2025, 17(5), 595; https://doi.org/10.3390/polym17050595 - 24 Feb 2025
Viewed by 503
Abstract
Thermoplastic fiber-reinforced polymer (FRP) reinforcement has a significant advantage over traditional thermosetting FRP reinforcements in that it can be bent on site by heating-softening processing. However, current experimental and theoretical research on the thermal conductivity and heating-softening processing characteristics of thermoplastic FRP reinforcements [...] Read more.
Thermoplastic fiber-reinforced polymer (FRP) reinforcement has a significant advantage over traditional thermosetting FRP reinforcements in that it can be bent on site by heating-softening processing. However, current experimental and theoretical research on the thermal conductivity and heating-softening processing characteristics of thermoplastic FRP reinforcements is quite insufficient. Through heating-softening processing tests, numerical simulation, and theoretical calculation, this study investigated the heating-softening processing time of a thermoplastic glass-fiber-reinforced polypropylene (GFRPP) reinforcement. In the heat transfer process, thermal conductivity is typically treated as a constant. However, the experimental results indicated that the thermal conductivity/diffusivity coefficient of the GFRPP reinforcement was temperature-dependent. On this basis, an equivalent modified thermal diffusivity coefficient of glass fiber was proposed to account for the time-temperature-dependent heat conductivity of the GFRPP reinforcement, utilizing a series model. Utilizing the modified thermal diffusivity coefficient, the simulation model presented a heating-softening processing time that coincided well with the experimental results, with a mean ratio of 1.005 and a coefficient of variation of 0.033. Moreover, based on an equivalent homogeneous circular cross-section assumption of the GFRPP reinforcement, an analytical solution to the heat conduction equation was derived. Combining the experimental and simulation results, a semi-analytical and semi-empirical calculation model was also proposed for predicting the heating-softening processing time of a GFRPP reinforcement with a silicone tube cover. The model’s calculated results align with the simulation trends, with an average deviation of 1.0% and a coefficient of variation of 0.026, demonstrating strong potential for engineering applications. Full article
(This article belongs to the Special Issue Processing, Characterization and Engineering Application of Fiber-Reinforced Thermoplastic Polymer Composites)
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17 pages, 7097 KiB  
Article
Numerical Prediction and Experimental Validation of Deposited Filaments in Direct Ink Writing: Deposition Status and Profile Dimension
by Yongqiang Tu, Haoran Zhang, Xue Shi, Jianyu Fan, Baohua Bao, Gang Lu, Fuwei Han, Hao Wu and Alaa Hassan
Polymers 2025, 17(5), 573; https://doi.org/10.3390/polym17050573 - 21 Feb 2025
Cited by 1 | Viewed by 354
Abstract
The deposition status and profile dimension of deposited filaments have an impact on the quality of the printed parts fabricated by direct ink writing (DIW). Previous works often failed to realize the full quantitative characterizations of the detailed influence of the process parameters [...] Read more.
The deposition status and profile dimension of deposited filaments have an impact on the quality of the printed parts fabricated by direct ink writing (DIW). Previous works often failed to realize the full quantitative characterizations of the detailed influence of the process parameters on the deposition status and profile dimension. Herein, we predict and analyze the deposition status and profile dimension by proposing an improved three-dimensional (3D) numerical model. The prediction accuracy of the proposed numerical model is verified through filament deposition experiments. The maximum relative errors of width and height between the experimental and simulation results of cross-sections are 10.13% and 7.37%, respectively. The effect of process parameters on the deposition status and profile dimension has been quantified. Critical process parameters are identified as the dimensionless nozzle velocity (V*) and the dimensionless height (H*). Three deposition statuses named over-deposition, pressed deposition and freeform deposition are characterized depending on the combination of V* and H*. The current work demonstrates an effective approach for the prediction of the deposition status and profile dimension of the deposited filaments along with the investigation of the effects of process parameters in DIW based on numerical simulations. Full article
(This article belongs to the Section Polymer Physics and Theory)
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17 pages, 3763 KiB  
Article
Bio-Based and Solvent-Free Epoxy Vitrimers Based on Dynamic Imine Bonds with High Mechanical Performance
by Lei Chen, Na Ning, Gang Zhou, Yan Li, Shicheng Feng, Zhengyan Guo and Yi Wei
Polymers 2025, 17(5), 571; https://doi.org/10.3390/polym17050571 - 21 Feb 2025
Viewed by 636
Abstract
Conventional epoxy thermosets, with irreversible crosslinking networks, cannot be reprocessed and recycled. Furthermore, the utilization of petroleum-based materials accelerates the depletion of non-renewable resources. The introduction of dynamic covalent bonds and the use of bio-based materials for thermosets can effectively address the above [...] Read more.
Conventional epoxy thermosets, with irreversible crosslinking networks, cannot be reprocessed and recycled. Furthermore, the utilization of petroleum-based materials accelerates the depletion of non-renewable resources. The introduction of dynamic covalent bonds and the use of bio-based materials for thermosets can effectively address the above issues. Herein, a series of bio-based epoxy vitrimers with dynamic covalent imine bonds were synthesized via a simple solvent-free, one-pot method using vanillin-derived aldehyde monomers, 4,4-diaminodiphenylsulfone (DDS) and bisphenol F diglycidyl ether (BFDGE) as raw materials. The effect of crosslinking density, crosslinking structure and imine bond content on the resulting bio-based vitrimers was studied, demonstrating their excellent thermal properties, UV shielding and solvent resistance, as well as outstanding mechanical properties compared to those of the previously reported vitrimers. In particular, the cured neat resin of vitrimer had a maximum tensile strength of 109 MPa and Young’s modulus of 6257 MPa, which are higher than those of previously reported imine-based vitrimers. The dynamic imine bonds endow these vitrimers with good reprocessability upon heating (over 70% recovery) and degradation under acidic conditions, enabling recycling by physical routes and gentle degradation by chemical routes. This study demonstrates a simple and effective process to prepare high-performance bio-based and recycled epoxy thermosets. Full article
(This article belongs to the Special Issue Bio-Based and Biodegradable Polymers: Synthesis, Characterization and Applications)
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19 pages, 3225 KiB  
Article
Tailoring Thermomechanical, Shape Memory and Self-Healing Properties of Furan-Based Polyketone via Diels-Alder Chemistry with Different Bismaleimide Crosslinkers
by Esteban Araya-Hermosilla, Marco Carlotti, Felipe Orozco, Guilherme Macedo R. Lima, Rodrigo Araya-Hermosilla, Daniela E. Ortega, Diego Cortés-Arriagada, Francesco Picchioni, Ranjita K. Bose, Virgilio Mattoli and Andrea Pucci
Polymers 2025, 17(5), 565; https://doi.org/10.3390/polym17050565 - 20 Feb 2025
Viewed by 552
Abstract
Furan/maleimide dynamic covalent chemistry has been extensively used to fabricate re-workable and self-healing thermosets. Understanding the relationship between crosslinker structure, network dynamics, and material final properties, however, remains a challenge. This study introduces self-healing and shape-memory thermosets derived from furan-functionalized polyketones (PKFU) crosslinked [...] Read more.
Furan/maleimide dynamic covalent chemistry has been extensively used to fabricate re-workable and self-healing thermosets. Understanding the relationship between crosslinker structure, network dynamics, and material final properties, however, remains a challenge. This study introduces self-healing and shape-memory thermosets derived from furan-functionalized polyketones (PKFU) crosslinked with aromatic bis-maleimides, i.e., 1,1′-(methylenedi-4,1-phenylene)bis-maleimide (BISM1) and bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (BISM2), via a thermally reversible Diels-Alder reaction. Polyketones were chemically modified with furfurylamine through the Paal-Knorr reaction, achieving varying furan grafting ratios. The resulting networks, characterized by ATR-FTIR, 1H-NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and rheology, demonstrated tunable thermomechanical properties. BISM2-based thermosets exhibited enhanced thermal stability and reversibility over a broad temperature range (20–120 °C), with a shape recovery ratio of up to 89% and complete self-healing at 120 °C within 5 min. These findings highlight the potential of polyketone-based thermosets for applications requiring adaptive thermomechanical properties, efficient self-repair, and sustainability. Full article
(This article belongs to the Section Polymer Chemistry)
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15 pages, 3735 KiB  
Article
Development of Smart Material Identification Equipment for Sustainable Recycling in Future Smart Cities
by Gaku Manago, Tadao Tanabe, Kazuaki Okubo, Tetsuo Sasaki and Jeongsoo Yu
Polymers 2025, 17(4), 462; https://doi.org/10.3390/polym17040462 - 10 Feb 2025
Cited by 1 | Viewed by 835
Abstract
Waste recycling is critical for the development of smart cities. Local authorities are responsible for the disposal of waste plastics, but the extent of material recycling is insufficient, and much of the waste generated is incinerated. This conflicts with the trend of decarbonisation. [...] Read more.
Waste recycling is critical for the development of smart cities. Local authorities are responsible for the disposal of waste plastics, but the extent of material recycling is insufficient, and much of the waste generated is incinerated. This conflicts with the trend of decarbonisation. Of particular note are the effects of the COVID-19 pandemic, during and after which large quantities of waste plastics, such as plastic containers and packaging, were generated. In order to develop a sustainable smart city, we need an effective scheme where we can separate materials before they are taken to the local authorities and recyclers. In other words, if material identification can be performed at the place of disposal, the burden on recyclers can be reduced, and a smart city can be created. In this study, we developed and demonstrated smart material identification equipment for waste plastic materials made of PET, PS, PP, and PE using GaP THz and sub-THz wavelengths. As basic information, we used a GaP terahertz spectrometer to sweep frequencies from 0.5 THz to 7 THz and measure the spectrum, and the transmittance rate was measured using the sub-THz device. The sub-THz device used a specific frequency below 0.14 THz. This is a smaller, more carriable, and less expensive semiconductor electronic device than the GaP. Moreover, the sub-terahertz device used in the development of this equipment is compact, harmless to the human body, and can be used in public environments. As a result, smart equipment was developed and tested in places such as supermarkets, office entrances, and canteens. The identification of materials can facilitate material recycling. In this study, we found that measuring devices designed to identify the PET and PS components of transparent containers and packaging plastics, and the PP and PE components of PET bottle caps, could effectively identify molecular weights, demonstrating new possibilities for waste management and recycling systems in smart cities. With the ability to collect and analyse data, these devices can be powerful tools for pre-sorting. Full article
(This article belongs to the Special Issue Polymer Composites in Municipal Solid Waste Landfills)
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16 pages, 3868 KiB  
Article
Development of Zein–PEG400/PVA–Chitosan Bilayer Films for Intelligent Packaging
by Rong Sun, Liangliang Li, Jiangjie Zhou, Yongfeng Zhang, Haiya Sun, Datong Zhang and Qi Wu
Polymers 2025, 17(3), 387; https://doi.org/10.3390/polym17030387 - 31 Jan 2025
Viewed by 985
Abstract
Zein exhibits excellent biodegradability, thermal stability, UV resistance, and water barrier properties, making it a promising candidate for food packaging applications. However, pure zein films suffer from brittleness and poor mechanical strength, which limit their practical use. In this study, a unique bilayer [...] Read more.
Zein exhibits excellent biodegradability, thermal stability, UV resistance, and water barrier properties, making it a promising candidate for food packaging applications. However, pure zein films suffer from brittleness and poor mechanical strength, which limit their practical use. In this study, a unique bilayer packaging film (ZP/P-C) was developed using a layer-by-layer solution casting technique, where hydrophobic zein was coated onto a polyvinyl alcohol and chitosan composite layer (P-C). Incorporating PEG400 into the zein layer improved the interfacial compatibility of the bilayer film, increasing its uniformity and toughness. The resulting bilayer films demonstrated enhanced mechanical properties, flexibility, and water vapor barrier performance. Specifically, the ZP7.5/P-C bilayer film showed an elongation at break of 68.74% and a modulus of elasticity of 187.19 MPa. It had a water vapor permeability of 6.60 × 10−11 g·m·m−2·s−1·Pa−1 and provided near-complete UV protection within the 200–350 nm range. Furthermore, an intelligent detection bilayer film was created by integrating anthocyanin extract into the zein layer. Adding anthocyanin improved the film’s antioxidant properties and allowed it to respond colorimetrically to total volatile basic nitrogen. The bilayer film ZPBA1.0/P-C displayed an excellent antioxidant activity (45.8%) and remarkable color change (ΔE = 20.2) in response to ammonia, effectively indicating shrimp spoilage in 48 h (ΔE > 10). This investigation spotlights the potential of zein-based bilayer films in active and intelligent food packaging, offering innovative strategies to improve food safety and extend the shelf life of perishable goods. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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12 pages, 7575 KiB  
Article
Polymer Composite Films with P(VDF-TrFE) and Molecular Ferroelectric Tris(hydroxymethyl) Nitromethane: Improvement of Their Ferroelectric Properties
by Marianela Escobar-Castillo, Samet Duman and Doru C. Lupascu
Polymers 2025, 17(3), 354; https://doi.org/10.3390/polym17030354 - 28 Jan 2025
Viewed by 740
Abstract
Polymer composites of P(VDF-TrFE) and Tris(hydroxymethyl) nitromethane as filler material with different concentrations have been prepared. Tris(hydroxymethyl) nitromethane is an organic ferroelectric material with low preparation cost and easy processing, and it is also lightweight. Its properties enable it to be a potential [...] Read more.
Polymer composites of P(VDF-TrFE) and Tris(hydroxymethyl) nitromethane as filler material with different concentrations have been prepared. Tris(hydroxymethyl) nitromethane is an organic ferroelectric material with low preparation cost and easy processing, and it is also lightweight. Its properties enable it to be a potential candidate for use as filler material in polymers to improve their ferroelectric, dielectric, and piezoelectric properties. We investigated the effect of filler content on the ferroelectric and dielectric properties of the polymer. Our results show that Tris(hydroxymethyl) nitromethane retains its crystallinity after embedding it in the polymer matrix. It does not alter the crystalline ferroelectric β-phase of the polymer. All composites possess higher polarization compared to pure P(VDF-TrFE). Up to 11.4 µC/cm2 remnant polarization and a dielectric constant of 14 at 1000 Hz have been obtained with the free-standing 10 wt% composite film. Full article
(This article belongs to the Special Issue Functional Polymer Composites: Synthesis, Characterization and Application II)
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31 pages, 1619 KiB  
Review
Devulcanization of Waste Tire Rubber via Microwave and Biological Methods: A Review
by Mostafa Vahdatbin, Pouria Hajikarimi and Ellie H. Fini
Polymers 2025, 17(3), 285; https://doi.org/10.3390/polym17030285 - 22 Jan 2025
Viewed by 1419
Abstract
This paper presents a thorough literature review on devulcanization methods applied to waste tire rubber: “microwave devulcanization” and “biological desulfurization”. To do so, 80 papers published from the year 1990 to 2024 in journals with subscription and open access status across 12 databases [...] Read more.
This paper presents a thorough literature review on devulcanization methods applied to waste tire rubber: “microwave devulcanization” and “biological desulfurization”. To do so, 80 papers published from the year 1990 to 2024 in journals with subscription and open access status across 12 databases were reviewed. This paper compares the efficacy and reviews the basic concepts, advantages, processes, and variable parameters of these two methods. In microwave devulcanization, microwave energy breaks the sulfur crosslinks between polymer chains. The latter breakage is mainly enabled by the presence of carbon black in the tire, which is an excellent microwave absorbent. In biological desulfurization, bacteria or fungi convert the crosslinks to elemental sulfur substances or sulfate. In general, microwave devulcanization of rubber leads to a lower crosslink density and thus a higher degree of devulcanization. On the one hand, breaking the crosslinks requires a significantly shorter time than biological desulfurization. Crosslink scission occurs throughout the sample in microwave devulcanization but only on the sample surface in biological desulfurization. Microwave devulcanization is not sensitive to rubber additives and does not require detoxification before devulcanization. On the other hand, biological desulfurization requires detoxification before devulcanization since it involves living organisms that may not tolerate certain rubber additives. Full article
(This article belongs to the Special Issue High Performance Rubber Materials: From Fundamental to Advanced Applied Science)
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36 pages, 6105 KiB  
Review
An Overview of Potential Applications of Environmentally Friendly Hybrid Polymeric Materials
by Raluca Nicoleta Darie-Niță and Stanisław Frąckowiak
Polymers 2025, 17(2), 252; https://doi.org/10.3390/polym17020252 - 20 Jan 2025
Viewed by 1552
Abstract
The applications of polymeric materials are being constantly reviewed and improved. In the present world, the word hybrid, and the general idea of combining two or more inherently different approaches, designs, and materials is gaining significant attention. The area of sustainable materials with [...] Read more.
The applications of polymeric materials are being constantly reviewed and improved. In the present world, the word hybrid, and the general idea of combining two or more inherently different approaches, designs, and materials is gaining significant attention. The area of sustainable materials with a low environmental impact is also rapidly evolving with many new discoveries, including the use of materials of a natural origin and countless combinations thereof. This review tries to summarize the current state of knowledge about hybrid polymeric materials and their applications with special attention to the materials that can be considered “environmentally friendly”. As the current application field is quite broad, the review was limited to the following topics: packaging, medical applications, sensors, water purification, and electromagnetic shielding. Furthermore, this review points out the new prospects and challenges for the use of the mentioned materials in terms of creating novel solutions with different nano and micro-materials of mostly natural and renewable origin. Full article
(This article belongs to the Special Issue Advanced Environmentally Friendly Polymeric Materials and Their Applications, 2nd Edition)
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20 pages, 2190 KiB  
Article
Sustainable 3D Scaffolds Based on β-Chitin and Collagen I for Wound Dressing Applications
by Marianna Barbalinardo, Giuseppe Falini and Devis Montroni
Polymers 2025, 17(2), 140; https://doi.org/10.3390/polym17020140 - 8 Jan 2025
Viewed by 885
Abstract
The development of greener substitutes for plastics is gaining massive importance in today’s society. This also involves the medical field, where disposable materials are used to grant sterility. Here, a novel protocol using only a water-based solvent for the preparation of bio-based composite [...] Read more.
The development of greener substitutes for plastics is gaining massive importance in today’s society. This also involves the medical field, where disposable materials are used to grant sterility. Here, a novel protocol using only a water-based solvent for the preparation of bio-based composite foams of actual β-chitin and collagen type I is presented. The influence of the ratio of this chitin polymorph to the collagen on the final material is then studied. The samples with 50:50 and 75:25 ratios produce promising results, such as remarkable water absorption (up to 7000 wt.%), exposed surface (up to 7 m2·g−1), and total pore volume (over 80 vol.%). The materials are also tested using wet mechanical compression, exhibiting a Young’s modulus and tenacity (both calculated between 2% and 25% of deformation) of up to 20 Pa and 9 kPa, respectively. Fibroblasts, keratinocytes, and osteoblasts are grown on these scaffolds. The viability of fibroblasts and keratinocytes is observed for 72 h, whereas the viability of osteoblasts is observed for up to 21 days. Under the two conditions mentioned, cell activity and adhesion work even better than under its counterpart condition of pure collagen. In conclusion, these materials are promising candidates for sustainable regenerative medicine scaffolds or, specifically, as biodegradable wound dressings. Full article
(This article belongs to the Special Issue Biopolymer Composites for Biomedicine Applications)
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19 pages, 2565 KiB  
Article
Fine-Tuning the Physicochemical Properties of Poly(lactic Acid) Nanoparticles for the Controlled Release of the BET Inhibitor JQ1: Influence of PVA Concentration
by Nedjla Kedjar, Eleonora Iannuzzi, Martin Kreuzer, Carlos Alonso-Moreno and Carmen Moya-Lopez
Polymers 2025, 17(1), 123; https://doi.org/10.3390/polym17010123 - 6 Jan 2025
Viewed by 780
Abstract
The compounds targeting the bromo and extra terminal domain proteins (BET), such as the JQ1, present potent anti-cancer activity in preclinical models, however, the application of JQ1 at the clinical level is limited by its short half-life, rapid clearance, and non-selective inhibition of [...] Read more.
The compounds targeting the bromo and extra terminal domain proteins (BET), such as the JQ1, present potent anti-cancer activity in preclinical models, however, the application of JQ1 at the clinical level is limited by its short half-life, rapid clearance, and non-selective inhibition of BET family proteins, leading to off-target effects and resistance. To address these challenges, the optimization of JQ1 delivery has been accomplished through polylactide (PLA) nanoparticles. PLA derivatives with varying molecular weights were synthesized via ring-opening polymerization using a zinc-based initiator and characterized using thermogravimetric analysis, differential scanning calorimetry, and infrared spectroscopy. PLA nanoparticles (NPs) were subsequently formulated, and the effects of key parameters—including PLA molecular weight, organic phase concentration, and surfactant concentration—on particle size, polydispersity index (PDI), and encapsulation efficiency were systematically investigated. PLA molecular weight and organic phase concentration mainly influenced the NPs size whilst the thermodynamic state of the NPs was unaffected by these two parameters. The surfactant concentration is correlated to the encapsulation efficacy of JQ1 as well as the release profile, suggesting the potential tool that the variation of these parameters represent for customizing the release of JQ1 according to specific needs. Full article
(This article belongs to the Special Issue Hybrid Polymeric Nanomaterials for Energy, Biomedical and Environmental Applications)
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17 pages, 8938 KiB  
Article
Designing Microparticles of Luteolin and Naringenin in Different Carriers via Supercritical Antisolvent Process
by Stefania Mottola and Iolanda De Marco
Polymers 2024, 16(24), 3600; https://doi.org/10.3390/polym16243600 - 23 Dec 2024
Viewed by 513
Abstract
Antioxidants are contained in fruits and vegetables and are commonly obtained through food. However, it is frequently necessary to supplement the diet with substances that are often poorly soluble in water and sensitive to light and oxygen. For this reason, in this work, [...] Read more.
Antioxidants are contained in fruits and vegetables and are commonly obtained through food. However, it is frequently necessary to supplement the diet with substances that are often poorly soluble in water and sensitive to light and oxygen. For this reason, in this work, luteolin (LUT) and naringenin (NAR), two compounds with antioxidant activity and potential health benefits, were precipitated through the supercritical antisolvent technique using polyvinylpyrrolidone and β-cyclodextrin as the carriers. The precipitation occurred from dimethylsulfoxide using supercritical carbon dioxide as the antisolvent. The influence of pressure (9–12 MPa), active substance/carrier concentration in the solution (20–200 mg/mL), and their ratio (1/1 and 1/2 mol/mol) on morphology, particle mean size, and distribution were investigated. Under the optimized operating conditions, spherical microparticles with a mean diameter equal to 2.7 ± 0.9 μm (for LUT) and 5.5 ± 1.9 μm (for NAR) were obtained. The active ingredients were protected from the external environment by the presence of the carrier, and the dissolution rate was notably increased by processing them with β-cyclodextrin. It was sixty times faster and three times faster than that of the antioxidant alone for LUT and NAR, respectively. Full article
(This article belongs to the Section Polymer Applications)
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16 pages, 5814 KiB  
Article
Effects of the Hot-Drawing Process on the Pore Parameters, Gas Absorption and Mechanical Performances of Activated Carbon-Loaded Porous Poly(m-Phenylene Isophthalamide) Composite Fibres
by Xiaosong Li, Bo Li, Qibin Xu, Lingcheng Meng, Deyang Wu, Pengqing Liu, Fabien Salaün and Shengchang Zhang
Polymers 2024, 16(24), 3452; https://doi.org/10.3390/polym16243452 - 10 Dec 2024
Viewed by 819
Abstract
Poor breathability, inadequate flexibility, bulky wearability, and insufficient gas-adsorption capacity always limit the developments and applications of conventional chemical protective clothing (CPC). To create a lightweight, breathable, and flexible fabric with a high gas-absorption capacity, activated carbon (AC)-loaded poly(m-phenylene isophthalamide) (PMIA) porous composite [...] Read more.
Poor breathability, inadequate flexibility, bulky wearability, and insufficient gas-adsorption capacity always limit the developments and applications of conventional chemical protective clothing (CPC). To create a lightweight, breathable, and flexible fabric with a high gas-absorption capacity, activated carbon (AC)-loaded poly(m-phenylene isophthalamide) (PMIA) porous composite fibres were fabricated from a mixed wet-spinning process integrated with a solvent-free phase separation process. By manipulating the pore parameters of as-spun composite fibres, the exposure-immobilization of AC particles on the fibre surface can offer a higher gas-absorption capacity and better AC-loading stability. To improve the mechanical properties of AC-loaded porous as-spun fibres and further optimize the pore-locking structures, the impact of the hot-drawing process on the evolution of pore parameters and the corresponding properties (including the gas absorption capacity, the mechanical performance, and the stability of AC particles during loading) was clarified. After the hot-drawing process, the inhomogeneous pore morphologies composed of mesopores/micropores from as-spun fibres changed into homogeneous and decreased mesopores. With the decrease in structural defects in homogeneous morphologies, the tensile strength of AC-loaded PMIA porous-drawn fibres increased to 1.5 cN/dtex. Meanwhile, the greater total pore volume and specific surface area after hot drawing also maintained the gas-absorption capacity of drawn composite fibres at 98.53 mg/g. Furthermore, the AC-loaded PMIA porous composite fibres also showed comparable performance to the commercial FFF02 absorption layer in terms of static absorption behaviour for different gas molecules and absorption–desorption multi-cycling evaluations. In addition, due to the size reduction in mesopores after the hot-drawing process, the loading stability of AC particles in the stretched composite fibres was more substantial. Full article
(This article belongs to the Special Issue Technical Textile Science and Technology)
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42 pages, 49473 KiB  
Review
Electrospun Micro/Nanofiber-Based Electrocatalysts for Hydrogen Evolution Reaction: A Review
by Xiuhong Li, Youqi He, Kai Li, Shuailong Zhang, Xinyu Hu, Yi Li, Daode Zhang and Yong Liu
Polymers 2024, 16(22), 3155; https://doi.org/10.3390/polym16223155 - 13 Nov 2024
Cited by 2 | Viewed by 1372
Abstract
Hydrogen is regarded as an ideal energy carrier to cope with the energy crisis and environmental problems due to its high energy density, cleanliness, and renewability. Although there are several primary methods of industrial hydrogen production, hydrogen evolution reaction (HER) is an efficient, [...] Read more.
Hydrogen is regarded as an ideal energy carrier to cope with the energy crisis and environmental problems due to its high energy density, cleanliness, and renewability. Although there are several primary methods of industrial hydrogen production, hydrogen evolution reaction (HER) is an efficient, eco-friendly, and sustainably green method for the preparation of hydrogen which has attracted considerable attention. However, this technique is characterized by slow reaction kinetics and high energy potential owing to lack of electrocatalysts with cost-effective and high performance which impedes its scale-up. To address this issue, various studies have focused on electrospun micro/nanofiber-based electrocatalysts for HER due to their excellent electron and mass transport, high specific surface area, as well as high porosity and flexibility. To further advance their development, recent progress of highly efficient HER electrospun electrocatalysts is reviewed. Initially, the characteristics of potential high-performance electrocatalysts for HER are elucidated. Subsequently, the advantages of utilizing electrospinning technology for the preparation of electrocatalysts are summarized. Then, the classification of electrospun micro/nanofiber-based electrocatalysts for HER are analyzed, including metal-based electrospun electrocatalyst (noble metals and alloys, transition metals, and alloys), metal–non-metal electrocatalysts (metal sulfide-based electrocatalysts, metal oxide-based electrocatalysts, metal phosphide-based electrocatalysts, metal nitride-based electrocatalysts, and metal carbide-based electrocatalysts), metal-free electrospun micro/nanofiber-based electrocatalysts, and hybrid electrospun micro/nanofiber-based electrocatalysts. Following this, enhancement strategies for electrospun micro/nanofiber-based electrocatalysts are discussed. Finally, current challenges and the future research directions of electrospun micro/nanofiber-based electrocatalysts for HER are concluded. Full article
(This article belongs to the Special Issue Polymer Electrolyte: Recent Progress and Applications (2nd Edition))
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16 pages, 11639 KiB  
Article
Tribological and Hygroscopic Behavior of Polybutylene Terephthalate/Acrylonitrile Styrene Acrylate (PBT/ASA) Nanocomposites with Graphene Nanofiller
by Pyoung-Chan Lee, Seo-Hwa Hong, Ji Taek Oh, Donghyeok Shin, Jae-Uk Jung, Youn Ki Ko, Jin Uk Ha, Myeong-Gi Kim and Beom-Gon Cho
Polymers 2024, 16(22), 3149; https://doi.org/10.3390/polym16223149 - 12 Nov 2024
Viewed by 1051
Abstract
Fogging in automotive headlamps is a significant issue that affects both aesthetics and functionality. This study investigates the use of graphene-based nanocomposites to mitigate fogging by enhancing the hygroscopic properties of polybutylene terephthalate/acrylonitrile styrene acrylate (PBT/ASA) composites commonly used in headlamps. The incorporation [...] Read more.
Fogging in automotive headlamps is a significant issue that affects both aesthetics and functionality. This study investigates the use of graphene-based nanocomposites to mitigate fogging by enhancing the hygroscopic properties of polybutylene terephthalate/acrylonitrile styrene acrylate (PBT/ASA) composites commonly used in headlamps. The incorporation of functionalized graphene improved the tensile and flexural strength of the nanocomposites, though it led to a reduction in elongation and melt flow. Additionally, the solid lubrication properties and increased surface hardness of the graphene contributed to enhanced wear resistance. The presence of graphene in the nanocomposites also reduced moisture diffusion, lowering the rates of both hygroscopic and desorption when compared to commercial PBT/ASA composites. Furthermore, the nanocomposites exhibited a reduction in maximum moisture uptake. These improvements are expected to reduce the absolute humidity inside the headlamp, thereby effectively mitigating the fogging issue. Full article
(This article belongs to the Special Issue Advances in Functional Polymer Nanocomposites)
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35 pages, 1165 KiB  
Review
Natural-Fiber-Reinforced Polymer Composites for Furniture Applications
by Mariana Ichim, Emil Ioan Muresan and Elena Codau
Polymers 2024, 16(22), 3113; https://doi.org/10.3390/polym16223113 - 6 Nov 2024
Cited by 4 | Viewed by 3893
Abstract
Increasing environmental awareness has driven a shift in furniture production from traditional materials, such as wood and wood-based panels, to sustainable and environmentally friendly alternatives, such as natural-fiber-reinforced (NFR) composites. Environmental consciousness has become a key factor in both production and consumer choices, [...] Read more.
Increasing environmental awareness has driven a shift in furniture production from traditional materials, such as wood and wood-based panels, to sustainable and environmentally friendly alternatives, such as natural-fiber-reinforced (NFR) composites. Environmental consciousness has become a key factor in both production and consumer choices, with growing demand for sustainably sourced materials, eco-friendly manufacturing processes, and durable furniture that helps reduce the impact of disposable products on the environment. This paper analyzes various requirements for natural-fiber-reinforced polymer composites used in furniture applications, including performance, structural–functional, ecological, economical, and safety requirements. It discusses factors influencing the performance of composite materials, such as the selection of matrix and reinforcing fibers, the matrix-to-reinforcement ratio, and the choice of manufacturing technology, as well as the compatibility and bonding between the matrix and fibers. Additionally, several standards commonly used to determine the mechanical, physical, and chemical properties of these materials are presented. Full article
(This article belongs to the Special Issue Material-Process-Structure Integrated Design for Advanced Polymeric Composites)
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33 pages, 7096 KiB  
Review
Processing and Properties of Polyhydroxyalkanoate/ZnO Nanocomposites: A Review of Their Potential as Sustainable Packaging Materials
by Mieke Buntinx, Chris Vanheusden and Dries Hermans
Polymers 2024, 16(21), 3061; https://doi.org/10.3390/polym16213061 - 30 Oct 2024
Cited by 1 | Viewed by 1940
Abstract
The escalating environmental concerns associated with conventional plastic packaging have accelerated the development of sustainable alternatives, making food packaging a focus area for innovation. Bioplastics, particularly polyhydroxyalkanoates (PHAs), have emerged as potential candidates due to their biobased origin, biodegradability, and biocompatibility. PHAs stand [...] Read more.
The escalating environmental concerns associated with conventional plastic packaging have accelerated the development of sustainable alternatives, making food packaging a focus area for innovation. Bioplastics, particularly polyhydroxyalkanoates (PHAs), have emerged as potential candidates due to their biobased origin, biodegradability, and biocompatibility. PHAs stand out for their good mechanical and medium gas permeability properties, making them promising materials for food packaging applications. In parallel, zinc oxide (ZnO) nanoparticles (NPs) have gained attention for their antimicrobial properties and ability to enhance the mechanical and barrier properties of (bio)polymers. This review aims to provide a comprehensive introduction to the research on PHA/ZnO nanocomposites. It starts with the importance and current challenges of food packaging, followed by a discussion on the opportunities of bioplastics and PHAs. Next, the synthesis, properties, and application areas of ZnO NPs are discussed to introduce their potential use in (bio)plastic food packaging. Early research on PHA/ZnO nanocomposites has focused on solvent-assisted production methods, whereas novel technologies can offer additional possibilities with regard to industrial upscaling, safer or cheaper processing, or more specific incorporation of ZnO NPs in the matrix or on the surface of PHA films or fibers. Here, the use of solvent casting, melt processing, electrospinning, centrifugal fiber spinning, miniemulsion encapsulation, and ultrasonic spray coating to produce PHA/ZnO nanocomposites is explained. Finally, an overview is given of the reported effects of ZnO NP incorporation on thermal, mechanical, gas barrier, UV barrier, and antimicrobial properties in ZnO nanocomposites based on poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). We conclude that the functionality of PHA materials can be improved by optimizing the ZnO incorporation process and the complex interplay between intrinsic ZnO NP properties, dispersion quality, matrix–filler interactions, and crystallinity. Further research regarding the antimicrobial efficiency and potential migration of ZnO NPs in food (simulants) and the End-of-Life will determine the market potential of PHA/ZnO nanocomposites as active packaging material. Full article
(This article belongs to the Special Issue Processing, Characterization and Modeling of Polymer Nanocomposites)
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36 pages, 13579 KiB  
Review
Exploring the Possibilities of Using Recovered Collagen for Contaminants Removal—A Sustainable Approach for Wastewater Treatment
by Annette Madelene Dancila and Magdalena Bosomoiu
Polymers 2024, 16(20), 2923; https://doi.org/10.3390/polym16202923 - 18 Oct 2024
Viewed by 2142
Abstract
Collagen is a non-toxic polymer that is generated as a residual product by several industries (e.g., leather manufacturing, meat and fish processing). It has been reported to be resistant to bacteria and have excellent retention capacity. However, the recovered collagen does not meet [...] Read more.
Collagen is a non-toxic polymer that is generated as a residual product by several industries (e.g., leather manufacturing, meat and fish processing). It has been reported to be resistant to bacteria and have excellent retention capacity. However, the recovered collagen does not meet the requirements to be used for pharmaceutical and medical purposes. Due to the scarcity of water resources now affecting all continents, water pollution is a major concern. Another major field that could integrate the collagen generated as a by-product is wastewater treatment. Applications of collagen-based materials in wastewater treatment have been discussed in detail, and comparisons with already frequently used materials have been made. Over the last years, collagen-based materials have been tested for removal of both organic (e.g., pharmaceutical substances, dyes) and inorganic compounds (e.g., heavy metals, noble metals, uranium). They have also been tested for the manufacture of oil-water separation materials; therefore, they could be used for the separation of emulsified oily wastewater. Because they have been analysed for a wide range of substances, collagen-based materials could be good candidates for removing contaminants from wastewater streams that have seasonal variations in composition and concentration. The use of recovered collagen in wastewater treatment makes the method eco-friendly and cost efficient. This paper also discusses some of the challenges related to wastewater treatment: material stability, reuse and disposal. The results showed that collagen-based materials are renewable and reusable without significant loss of initial properties. In the sorption processes, the incorporation of experiments with real wastewater has demonstrated that there is a significant competition among the substances present in the sample. Full article
(This article belongs to the Special Issue Advanced Polymers for Wastewater Treatment and Toxicant Removal)
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15 pages, 1166 KiB  
Article
Sustainable Starch-Based Films from Cereals and Tubers: A Comparative Study on Cherry Tomato Preservation
by Kelly J. Figueroa-Lopez, Ángel Villabona-Ortíz and Rodrigo Ortega-Toro
Polymers 2024, 16(20), 2913; https://doi.org/10.3390/polym16202913 - 16 Oct 2024
Cited by 1 | Viewed by 1544
Abstract
Biodegradable films are sustainable alternatives to conventional plastics, particularly in food preservation, where the barrier and mechanical properties are crucial for maintaining the physicochemical, microbiological, and sensory qualities of the product. This study evaluated films made from starches of corn, potato, cassava, yam, [...] Read more.
Biodegradable films are sustainable alternatives to conventional plastics, particularly in food preservation, where the barrier and mechanical properties are crucial for maintaining the physicochemical, microbiological, and sensory qualities of the product. This study evaluated films made from starches of corn, potato, cassava, yam, and wheat to determine their effectiveness in preserving cherry tomatoes. Amylose content, a key factor influencing the crystallinity and properties of the films, varied among the sources, with wheat starch having the highest (28.2%) and cassava the lowest (18.3%). The wheat starch film emerged as the best formulation, exhibiting the highest tensile strength and the lowest water vapor permeability (4.1 ± 0.3 g∙mm∙m−2∙h−1∙KPa−1), contributing to superior barrier performance. When applied to cherry tomatoes, the films based on wheat and corn starch showed the least moisture loss over fifteen days, highlighting their potential in fresh food preservation. These results suggest that starch-based films, specifically those rich in amylose, have significant potential as biodegradable packaging materials for food product conservation. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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45 pages, 18357 KiB  
Review
Advances in the Application of Sulfonated Poly(Ether Ether Ketone) (SPEEK) and Its Organic Composite Membranes for Proton Exchange Membrane Fuel Cells (PEMFCs)
by Xiang Li, Tengling Ye, Xuan Meng, Dongqing He, Lu Li, Kai Song, Jinhai Jiang and Chuanyu Sun
Polymers 2024, 16(19), 2840; https://doi.org/10.3390/polym16192840 - 8 Oct 2024
Cited by 24 | Viewed by 4113
Abstract
This review discusses the progress of research on sulfonated poly(ether ether ketone) (SPEEK) and its composite membranes in proton exchange membrane fuel cells (PEMFCs). SPEEK is a promising material for replacing traditional perfluorosulfonic acid membranes due to its excellent thermal stability, mechanical property, [...] Read more.
This review discusses the progress of research on sulfonated poly(ether ether ketone) (SPEEK) and its composite membranes in proton exchange membrane fuel cells (PEMFCs). SPEEK is a promising material for replacing traditional perfluorosulfonic acid membranes due to its excellent thermal stability, mechanical property, and tunable proton conductivity. By adjusting the degree of sulfonation (DS) of SPEEK, the hydrophilicity and proton conductivity of the membrane can be controlled, while also balancing its mechanical, thermal, and chemical stability. Researchers have developed various composite membranes by combining SPEEK with a range of organic and inorganic materials, such as polybenzimidazole (PBI), fluoropolymers, and silica, to enhance the mechanical, chemical, and thermal stability of the membranes, while reducing fuel permeability and improving the overall performance of the fuel cell. Despite the significant potential of SPEEK and its composite membranes in PEMFCs, there are still challenges and room for improvement, including proton conductivity, chemical stability, cost-effectiveness, and environmental impact assessments. Full article
(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells: Technology and Applications)
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15 pages, 8620 KiB  
Article
Fabrication of Low-Cost Porous Carbon Polypropylene Composite Sheets with High Photothermal Conversion Performance for Solar Steam Generation
by Shuqing Xu, Shiyun Wu, Bin Xu, Jiang Ma, Jianjun Du and Jianguo Lei
Polymers 2024, 16(19), 2813; https://doi.org/10.3390/polym16192813 - 4 Oct 2024
Viewed by 1273
Abstract
The development of absorber materials with strong light absorption properties and low-cost fabrication processes is highly significant for the application of photothermal conversion technology. In this work, a mixed powder consisting of NaCl, polypropylene (PP), and scale-like carbon flakes was ultrasonically pressed into [...] Read more.
The development of absorber materials with strong light absorption properties and low-cost fabrication processes is highly significant for the application of photothermal conversion technology. In this work, a mixed powder consisting of NaCl, polypropylene (PP), and scale-like carbon flakes was ultrasonically pressed into sheets, and the NaCl was then removed by salt dissolution to obtain porous carbon polypropylene composite sheets (P-CPCS). This process is simple, green, and suitable for the low-cost, large-area fabrication of P-CPCS. P-CPCS has a well-distributed porous structure containing internal and external connected water paths. Under the dual effects of the carbon flakes and porous structure, P-CPCS shows excellent photothermal conversion performance in a broad wavelength range. P-CPCS-40 achieves a high temperature of 128 °C and a rapid heating rate of 12.4 °C/s under laser irradiation (808 nm wavelength, 1.2 W/cm2 power). When utilized for solar steam generation under 1 sun irradiation, P-CPCS-40 achieves 98.2% evaporation efficiency and a 1.81 kg m−2 h−1 evaporation rate. This performance means that P-CPCS-40 outperforms most other previously reported absorbers in terms of evaporation efficiency. The combination of carbon flakes, which provide a photothermal effect, and a porous polymer structure, which provides light-capturing properties, opens up a new strategy for desalination, sewage treatment, and other related fields. Full article
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19 pages, 2379 KiB  
Article
Spectroscopic and Thermal Characterisation of Interpenetrating Hydrogel Networks (IHNs) Based on Polymethacrylates and Pluronics, and Their Physicochemical Stability under Aqueous Conditions
by David S. Jones, Marion Westwood, Shu Li and Gavin P. Andrews
Polymers 2024, 16(19), 2796; https://doi.org/10.3390/polym16192796 - 1 Oct 2024
Viewed by 931
Abstract
This study describes the physicochemical characterisation of interpenetrating hydrogel networks (IHNs) composed of either poly(hydroxyethylmethacrylate, p(HEMA)) or poly(methacrylic acid, p(MAA)), and Pluronic block copolymers (grades F127, P123 and L121). IHNs were prepared by mixing the acrylate monomer with Pluronic block copolymers followed by [...] Read more.
This study describes the physicochemical characterisation of interpenetrating hydrogel networks (IHNs) composed of either poly(hydroxyethylmethacrylate, p(HEMA)) or poly(methacrylic acid, p(MAA)), and Pluronic block copolymers (grades F127, P123 and L121). IHNs were prepared by mixing the acrylate monomer with Pluronic block copolymers followed by free radical polymerisation. p(HEMA)–Pluronic blends were immiscible, evident from a lack of interaction between the two components (Raman spectroscopy) and the presence of the glass transitions (differential scanning calorimetry, DSC) of the two components. Conversely, IHNs of p(MAA) and each Pluronic were miscible, displaying a single glass transition and secondary bonding between the carbonyl group of p(MAA) and the ether groups in the Pluronic block copolymers (Raman and ATR-FTIR spectroscopy). The effect of storage of the IHNs in Tris buffer on the physical state of each Pluronic and on the loss of Pluronic from the IHNs were studied using DSC and gravimetric analysis, respectively. Pluronic loss from the IHNs was dependent on the grade of Pluronic, time of immersion in Tris buffer, and the nature of the IHN (p(HEMA) or p(MAA)). At equilibrium, the loss was greater from p(HEMA) than from p(MAA) IHNs, whereas increasing ratio of poly(propylene oxide) to poly(ethylene oxide) decreased Pluronic loss. The retention of each Pluronic grade was shown to be primarily due to its micellization; however, hydrogen bonding between Pluronic and p(MAA) (but not p(HEMA)) IHNs contributed to their retention. Full article
(This article belongs to the Special Issue Advances and Applications of Block Copolymers II)
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26 pages, 2290 KiB  
Article
Study of the Effect of Phosvitin as a Potential Carrier on the Permeation Process of Somatotropin (STH) and Corticotropin (ACTH) from Biodegradable Polymers Used as Vehicles for STH and ACTH in Semi-Solid Formulations for Skin Application
by Wioletta Siemiradzka, Karolina Kędzierska, Wojciech Rynk and Barbara Dolińska
Polymers 2024, 16(18), 2640; https://doi.org/10.3390/polym16182640 - 18 Sep 2024
Cited by 1 | Viewed by 1075
Abstract
Phosvitin shows chelating abilities, an affinity for ACTH (corticotropin), growth factors, antioxidant properties, and acidic nature. An attempt was made to use this protein in hydrogels as a transporter of other protein substances: somatotropin (STH) and (ACTH). The aim of the study was [...] Read more.
Phosvitin shows chelating abilities, an affinity for ACTH (corticotropin), growth factors, antioxidant properties, and acidic nature. An attempt was made to use this protein in hydrogels as a transporter of other protein substances: somatotropin (STH) and (ACTH). The aim of the study was to evaluate the effect of phosvitin on the permeation of ACTH and STH from semi-solid forms of the drug applied to the skin. Four hydrogel substrates were prepared using natural polymers: sodium alginate, methylcellulose, and starch. Based on the evaluation of physicochemical parameters, the hydrogel with the most favorable properties was selected and loaded with the active substances STH and ACTH, followed by the addition of phosvitin. A study of the permeation of STH and ACTH through the artificial cellulose membrane and through porcine skin was carried out without and with the addition of phosvitin. The effect of protein substances on rheological and textural parameters was studied. The evaluation of physicochemical parameters showed a favorable effect of STH and Phosvitin on the stability of the hydrogel with 4% methylcellulose and no effect of ACTH. All prepared formulations showed a reaction close to the natural pH of human skin. In the porcine skin permeation study, the addition of Phosvitin to the hydrogel with STH caused a slight increase in the amount of STH permeated and an increase in the time for STH to permeate porcine skin by 30 min. Phosvitin caused an increase in the amount of ACTH permeated through porcine skin almost twofold. Phosvitin may prove to be a promising permeation promoter for model protein-peptide substances when applied to the skin surface. Full article
(This article belongs to the Special Issue Biodegradable and Natural Polymers, 2nd Edition)
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20 pages, 8870 KiB  
Article
Oil Sorption Properties of Centrifugally Spun Polyisobutylene-Based Thermoplastic Elastomer Microfibers
by József Kántor, Gusztáv Fekete and Attila Levente Gergely
Polymers 2024, 16(18), 2624; https://doi.org/10.3390/polym16182624 - 17 Sep 2024
Cited by 1 | Viewed by 1035
Abstract
Fiber-based sorbent materials are an essential part of containing oil spills, thus preventing ecological damage. Poly(styrene-b-isobutylene-b-styrene) thermoplastic elastomer fibers were successfully produced by centrifugal spinning. Scanning electron microscopy revealed that the fibers were bead free and smooth-surfaced, with an [...] Read more.
Fiber-based sorbent materials are an essential part of containing oil spills, thus preventing ecological damage. Poly(styrene-b-isobutylene-b-styrene) thermoplastic elastomer fibers were successfully produced by centrifugal spinning. Scanning electron microscopy revealed that the fibers were bead free and smooth-surfaced, with an average fiber diameter of 5.9 ± 2.3 μm. Contact angle measurements proved the highly hydrophobic (water contact angle of 126.8 ± 6.4°) and highly oleophilic nature of the fiber mat. The sorption and retention capacities of the fiber mat were tested for various oils and benchmarked against polypropylene as the industry standard and polystyrene, which is widely used in the literature. The oil uptake of the fiber mat showed a strong correlation with the viscosity of the oil, resulting in sorption capacities of 10.1 ± 0.8 g/g for sunflower oil, 19.9 ± 2.1 g/g for motor oil, and 23.8 ± 1.8 g/g for gear oil. Oil–water separation tests were also conducted, resulting in ~100% oil removal. The thermoplastic elastomer fiber mat outperformed the industry standard; however, the polystyrene fiber mat demonstrated the best oil sorption performance. Full article
(This article belongs to the Special Issue Fiber Spinning Technologies and Functional Polymer Fiber Development)
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51 pages, 15779 KiB  
Review
A Review on the Application of Deep Eutectic Solvents in Polymer-Based Membrane Preparation for Environmental Separation Technologies
by Gorka Marco-Velasco, Alejandro Gálvez-Subiela, Ramón Jiménez-Robles, Marta Izquierdo, Amparo Cháfer and José David Badia
Polymers 2024, 16(18), 2604; https://doi.org/10.3390/polym16182604 - 14 Sep 2024
Cited by 6 | Viewed by 2544
Abstract
The use of deep eutectic solvents (DESs) for the preparation of polymer membranes for environmental separation technologies is comprehensively reviewed. DESs have been divided into five categories based on the hydrogen bond donor (HBD) and acceptor (HBA) that are involved in the production [...] Read more.
The use of deep eutectic solvents (DESs) for the preparation of polymer membranes for environmental separation technologies is comprehensively reviewed. DESs have been divided into five categories based on the hydrogen bond donor (HBD) and acceptor (HBA) that are involved in the production of the DESs, and a wide range of DESs’ physicochemical characteristics, such as density, surface tension, viscosity, and melting temperature, are initially gathered. Furthermore, the most popular techniques for creating membranes have been demonstrated and discussed, with a focus on the non-solvent induced phase separation (NIPS) method. Additionally, a number of studies have been reported in which DESs were employed as pore formers, solvents, additives, or co-solvents, among other applications. The addition of DESs to the manufacturing process increased the presence of finger-like structures and macrovoids in the cross-section and, on numerous occasions, had a substantial impact on the overall porosity and pore size. Performance data were also gathered for membranes made for various separation technologies, such as ultrafiltration (UF) and nanofiltration (NF). Lastly, DESs provide various options for the functionalization of membranes, such as the creation of various liquid membrane types, with special focus on supported liquid membranes (SLMs) for decarbonization technologies, discussed in terms of permeability and selectivity of several gases, including CO2, N2, and CH4. Full article
(This article belongs to the Special Issue Functional Polymers for Membrane Separation Process)
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22 pages, 6216 KiB  
Article
Synthesis and Dye Adsorption Dynamics of Chitosan–Polyvinylpolypyrrolidone (PVPP) Composite
by Hilda Dinah Kyomuhimbo, Wandile McHunu, Marco Arnold, Usisipho Feleni, Nils H. Haneklaus and Hendrik Gideon Brink
Polymers 2024, 16(18), 2555; https://doi.org/10.3390/polym16182555 - 10 Sep 2024
Cited by 1 | Viewed by 1840
Abstract
One major environmental issue responsible for water pollution is the presence of dyes in the aquatic environment as a result of human activity, particularly the textile industry. Chitosan–Polyvinylpolypyrrolidone (PVPP) polymer composite beads were synthesized and explored for the adsorption of dyes (Bismarck brown [...] Read more.
One major environmental issue responsible for water pollution is the presence of dyes in the aquatic environment as a result of human activity, particularly the textile industry. Chitosan–Polyvinylpolypyrrolidone (PVPP) polymer composite beads were synthesized and explored for the adsorption of dyes (Bismarck brown (BB), orange G (OG), brilliant blue G (BBG), and indigo carmine (IC)) from dye solution. The CS-PVPP beads demonstrated high removal efficiency of BB (87%), OG (58%), BBG (42%), and IC (49%). The beads demonstrated a reasonable surface area of 2.203 m2/g and were negatively charged in the applicable operating pH ranges. TGA analysis showed that the polymer composite can withstand decomposition up to 400 °C, proving high stability in harsh conditions. FTIR analysis highlighted the presence of N-H amine, O-H alcohol, and S=O sulfo groups responsible for electrostatic interaction and hydrogen bonding with the dye molecules. A shift in the FTIR bands was observed on N-H and C-N stretching for the beads after dye adsorption, implying that adsorption was facilitated by hydrogen bonding and Van der Waals forces of attraction between the hydroxyl, amine, and carbonyl groups on the surface of the beads and the dye molecules. An increase in pH increased the adsorption capacity of the beads for BB while decreasing OG, BBG, and IC due to their cationic and anionic nature, respectively. While an increase in temperature did not affect the adsorption capacity of OG and BBG, it significantly improved the removal of BB and IC from the dye solution and the adsorption was thermodynamically favoured, as demonstrated by the negative Gibbs free energy at all temperatures. Adsorption of dye mixtures followed the characteristic adsorption nature of the individual dyes. The beads show great potential for applications in the treatment of dye wastewater. Full article
(This article belongs to the Special Issue Advanced Polymers for Wastewater Treatment and Toxicant Removal)
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11 pages, 5047 KiB  
Article
Study on the Polymer Morphology and Electro-Optical Performance of Acrylate/Epoxy Resin-Based Polymer-Stabilized Liquid Crystals Based on Stepwise Photopolymerization
by Yishuo Wu, Guangyang Shang, Cong Ma, Yingjie Shi, Zhexu Song, Peixiang Wang, Yanzi Gao, Qian Wang, Meina Yu, Jiumei Xiao and Cheng Zou
Polymers 2024, 16(17), 2446; https://doi.org/10.3390/polym16172446 - 29 Aug 2024
Viewed by 1034
Abstract
Stepwise photopolymerization is a miraculous strategy modulating the polymer skeleton and electro-optical properties of light modulators based on liquid crystal/polymer composites. However, owing to the indistinct polymerization mechanism and curing condition discrepancy, the required polymer structures and electro-optical properties are hard to be [...] Read more.
Stepwise photopolymerization is a miraculous strategy modulating the polymer skeleton and electro-optical properties of light modulators based on liquid crystal/polymer composites. However, owing to the indistinct polymerization mechanism and curing condition discrepancy, the required polymer structures and electro-optical properties are hard to be controlled precisely. Herein, a novel polymer-stabilized liquid crystal film based on acrylate/epoxy resin is proposed, fabricated and the relationships between preparation process, polymer content, polymer morphology and electro-optical properties are studied. The in-situ photopolymerization of acrylate/epoxy resin liquid crystalline polymer is fulfilled using cation photo-initiator UV 6976. The distinct photopolymerization speed between acrylate and epoxy resin benefits the polymer morphology control, and with accurate containment of the polymerization process and polymer composition, the superior electro-optical properties at a higher polymer content are acquired. The polymer morphology and electro-optical properties are influenced by the polymer content and mass ratio between acrylate and epoxy resin. The best electro-optical properties among samples are attained by controlling the mass ratio between acrylate and epoxy resin to 1:1, integrating higher densities of scattering centers and lower anchoring effect. With higher polymer content, the strategy of increasing the mass ratio of E6M benefits the improvement of E-O properties for alleviating polymer density. This work provides insights to stepwise polymerization of liquid crystalline monomers and offers a fancy strategy for the preparation of novel liquid crystal dimming films. Full article
(This article belongs to the Special Issue Advanced Polymer Nanocomposites III)
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14 pages, 6036 KiB  
Review
Constructing Multifunctional Composite Single Crystals via Polymer Gel Incorporation
by Zhiwen Mao, Jie Ren and Hanying Li
Polymers 2024, 16(16), 2379; https://doi.org/10.3390/polym16162379 - 22 Aug 2024
Viewed by 1177
Abstract
The non-uniformity of a single crystal can sometimes be found in biominerals, where surrounding biomacromolecules are incorporated into the growing crystals. This unique composite structure, combining heterogeneity and long-range ordering, enables the functionalization of single crystals. Polymer gel media are often used to [...] Read more.
The non-uniformity of a single crystal can sometimes be found in biominerals, where surrounding biomacromolecules are incorporated into the growing crystals. This unique composite structure, combining heterogeneity and long-range ordering, enables the functionalization of single crystals. Polymer gel media are often used to prepare composite single crystals, in which the growing crystals incorporate gel networks and form a bi-continuous interpenetrating structure without any disruption to single crystallinity. Moreover, dyes and many kinds of nanoparticles can be occluded into single crystals under the guidance of gel incorporation. On this basis, the bio-inspired method has been applied in crystal morphology control, crystal dyeing, mechanical reinforcement, and organic bulk heterojunction-based optoelectronics. In this paper, the composite structure, the incorporation mechanisms, and the multiple functions of gel-incorporated single crystals are reviewed. Full article
(This article belongs to the Special Issue Advances in Polymers Science and Technology: From Nano-Engineering to Multifunctional Applications)
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17 pages, 7103 KiB  
Article
Cleaner and Sustainable Production of Core–Sheath Polymer Fibres
by Manul Amarakoon, Anthony Harker, Shervanthi Homer-Vanniasinkam and Mohan Edirisinghe
Polymers 2024, 16(16), 2357; https://doi.org/10.3390/polym16162357 - 20 Aug 2024
Cited by 1 | Viewed by 1088
Abstract
The amalgamation of sustainable practises throughout the fabrication process with advanced material engineering holds promise not only for eco-conscious manufacturing but also for promoting technological advancements in versatile material design and application. Moreover, technological innovation serves as a catalyst for sustainability initiatives, driving [...] Read more.
The amalgamation of sustainable practises throughout the fabrication process with advanced material engineering holds promise not only for eco-conscious manufacturing but also for promoting technological advancements in versatile material design and application. Moreover, technological innovation serves as a catalyst for sustainability initiatives, driving innovation and enabling the adoption of greener practises across industries. This study investigates redefining the production protocol of pressure spinning to produce core–sheath polymer fibres, deepening sustainable practises. It aims to explore innovative approaches such as modifying spinning parameters, optimising polymer solvent configurations and understanding fluid behaviour to curtail material wastage and maintain minimal energy consumption without compromising production efficiency. Utilising Polyvinylpyrrolidone (PVP) for the core and Polyethylene oxide (PEO) for the sheath, production rates of up to 64 g/h were achieved with a fibre diameter range of 3.2 ± 1.7 µm to 4.6 ± 2.0 µm. Energy consumption per mass of fibres produced showed a decreasing trend overall with increasing applied gas pressure. These findings highlight the potential for the efficient and scalable production of core–sheath fibres with applications in various advanced materials fields. Full article
(This article belongs to the Section Polymer Fibers)
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32 pages, 9337 KiB  
Review
Benefits of Incorporating Lignin into Starch-Based Films: A Brief Review
by Lamia Zuniga Linan, Farayde Matta Fakhouri, Gislaine Ferreira Nogueira, Justin Zoppe and José Ignacio Velasco
Polymers 2024, 16(16), 2285; https://doi.org/10.3390/polym16162285 - 13 Aug 2024
Cited by 5 | Viewed by 2225
Abstract
Polysaccharides are an excellent renewable source for developing food-packing materials. It is expected that these packages can be an efficient barrier against oxygen; can reduce lipid peroxidation, and can retain the natural aroma of a food commodity. Starch has tremendous potential to be [...] Read more.
Polysaccharides are an excellent renewable source for developing food-packing materials. It is expected that these packages can be an efficient barrier against oxygen; can reduce lipid peroxidation, and can retain the natural aroma of a food commodity. Starch has tremendous potential to be explored in the preparation of food packaging; however, due to their high hydrophilic nature, packaging films produced from starch possess poor protective moisture barriers and low mechanical properties. This scenario limits their applications, especially in humid conditions. In contrast, lignin’s highly complex aromatic hetero-polymer network of phenylpropane units is known to play a filler role in polysaccharide films. Moreover, lignin can limit the biodegradability of polysaccharides films by a physical barrier, mainly, and by non-productive bindings. The main interactions affecting lignin non-productive bindings are hydrophobic interactions, electrostatic interactions, and hydrogen-bonding interactions, which are dependent on the total phenolic –OH and –COOH content in its chemical structure. In this review, the use of lignin as a reinforcement to improve the biodegradability of starch-based films in wet environments is presented. Moreover, the characteristics of the used lignins, the mechanisms of molecular interaction among these materials, and the sensitive physicochemical parameters for biodegradability detection are related. Full article
(This article belongs to the Collection Lignin)
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20 pages, 11742 KiB  
Article
Large Enhancement of Photoluminescence Obtained in Thin Polyfluorene Films of Optimized Microstructure
by Otto Todor-Boer, Cosmin Farcău and Ioan Botiz
Polymers 2024, 16(16), 2278; https://doi.org/10.3390/polym16162278 - 11 Aug 2024
Cited by 1 | Viewed by 1465
Abstract
There is a clearly demonstrated relationship between the microstructure, processing and resulting optoelectronic properties of conjugated polymers. Here, we exploited this relationship by exposing polyfluorene thin films to various solvent vapors via confined-solvent vapor annealing to optimize their microstructure, with the final goal [...] Read more.
There is a clearly demonstrated relationship between the microstructure, processing and resulting optoelectronic properties of conjugated polymers. Here, we exploited this relationship by exposing polyfluorene thin films to various solvent vapors via confined-solvent vapor annealing to optimize their microstructure, with the final goal being to enhance their emission properties. Our results have demonstrated enlargements in photoluminescence intensity of up to 270%, 258% and 240% when thin films of polyfluorenes of average molecular weights of 105,491 g/mol, 63,114 g/mol and 14,000 g/mol, respectively, experienced increases in their β-phase fractions upon processing. Full article
(This article belongs to the Section Polymer Membranes and Films)
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12 pages, 1708 KiB  
Article
Fabricating High Strength Bio-Based Dynamic Networks from Epoxidized Soybean Oil and Poly(Butylene Adipate-co-Terephthalate)
by Bin Xu, Zhong-Ming Xia, Rui Zhan and Ke-Ke Yang
Polymers 2024, 16(16), 2280; https://doi.org/10.3390/polym16162280 - 11 Aug 2024
Viewed by 1493
Abstract
Amid the rapid development of modern society, the widespread use of plastic products has led to significant environmental issues, including the accumulation of non-degradable waste and extensive consumption of non-renewable resources. Developing healable, recyclable, bio-based materials from abundant renewable resources using diverse dynamic [...] Read more.
Amid the rapid development of modern society, the widespread use of plastic products has led to significant environmental issues, including the accumulation of non-degradable waste and extensive consumption of non-renewable resources. Developing healable, recyclable, bio-based materials from abundant renewable resources using diverse dynamic interactions attracts increasing global attention. However, achieving a good balance between the self-healing capacity and mechanical performance, such as strength and toughness, remains challenging. In our study, we address this challenge by developing a new type of dynamic network from epoxidized soybean oil (ESO) and poly(butylene adipate-co-terephthalate) (PBAT) with good strength and toughness. For the synthetic strategy, a thiol–epoxy click reaction was conducted to functionalize ESO with thiol and hydroxyl groups. Subsequently, a curing reaction with isocyanates generated dynamic thiourethane and urethane bonds with different bonding energies in the dynamic networks to reach a trade-off between dynamic features and mechanical properties; amongst these, the thiourethane bonds with a lower bonding energy provide good dynamic features, while the urethane bonds with a higher bonding energy ensure good mechanical properties. The incorporation of flexible PBAT segments to form the rational multi-phase structure with crystalline domains further enhanced the products. A typical sample, OTSO100-PBAT100, exhibited a tensile strength of 33.2 MPa and an elongation at break of 1238%, demonstrating good healing capacity and desirable mechanical performance. This study provides a promising solution to contemporary environmental and energy challenges by developing materials that combine mechanical and repair properties. It addresses the specific gap of achieving a trade-off between tensile strength and elongation at break in bio-based self-healing materials, promising a wide range of applications. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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15 pages, 6254 KiB  
Article
Effects of the Amylose/Amylopectin Ratio of Starch on Borax-Crosslinked Hydrogels
by Kai Lu, Rudy Folkersma, Vincent S. D. Voet and Katja Loos
Polymers 2024, 16(16), 2237; https://doi.org/10.3390/polym16162237 - 6 Aug 2024
Cited by 3 | Viewed by 3343
Abstract
Herein, we simultaneously prepared borax-crosslinked starch-based hydrogels with enhanced mechanical properties and self-healing ability via a simple one-pot method. The focus of this work is to study the effects of the amylose/amylopectin ratio of starch on the grafting reactions and the performance of [...] Read more.
Herein, we simultaneously prepared borax-crosslinked starch-based hydrogels with enhanced mechanical properties and self-healing ability via a simple one-pot method. The focus of this work is to study the effects of the amylose/amylopectin ratio of starch on the grafting reactions and the performance of the resulting borax-crosslinked hydrogels. An increase in the amylose/ amylopectin ratio increased the gel fraction and grafting ratio but decreased the swelling ratio and pore diameter. Compared with hydrogels prepared from low-amylose starches, hydrogels prepared from high-amylose starches showed pronouncedly increased network strength, and the maximum storage modulus increased by 8.54 times because unbranched amylose offered more hydroxyl groups to form dynamic borate ester bonds with borate ions and intermolecular hydrogen bonds, leading to an enhanced crosslink density. In addition, all the hydrogels exhibited a uniformly interconnected network structure. Furthermore, owing to the dynamic borate ester bonds and hydrogen bonds, the hydrogel exhibited excellent recovery behavior under continuous step strain, and it also showed thermal responsiveness. Full article
(This article belongs to the Special Issue Functional Polymers: Interaction, Surface, Processing and Applications: 2nd Edition)
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15 pages, 677 KiB  
Article
Correlative Effects on Nanoplastic Aggregation in Model Extracellular Biofilm Substances Investigated with Fluorescence Correlation Spectroscopy
by Tobias Guckeisen, Rozalia Orghici and Silke Rathgeber
Polymers 2024, 16(15), 2170; https://doi.org/10.3390/polym16152170 - 30 Jul 2024
Viewed by 1141
Abstract
Recent studies show that biofilm substances in contact with nanoplastics play an important role in the aggregation and sedimentation of nanoplastics. Consequences of these processes are changes in biofilm formation and stability and changes in the transport and fate of pollutants in the [...] Read more.
Recent studies show that biofilm substances in contact with nanoplastics play an important role in the aggregation and sedimentation of nanoplastics. Consequences of these processes are changes in biofilm formation and stability and changes in the transport and fate of pollutants in the environment. Having a deeper understanding of the nanoplastics–biofilm interaction would help to evaluate the risks posed by uncontrolled nanoplastic pollution. These interactions are impacted by environmental changes due to climate change, such as, e.g., the acidification of surface waters. We apply fluorescence correlation spectroscopy (FCS) to investigate the pH-dependent aggregation tendency of non-functionalized polystyrene (PS) nanoparticles (NPs) due to intermolecular forces with model extracellular biofilm substances. Our biofilm model consists of bovine serum albumin (BSA), which serves as a representative for globular proteins, and the polysaccharide alginate, which is a main component in many biofilms, in solutions containing Na+ with an ionic strength being realistic for fresh-water conditions. Biomolecule concentrations ranging from 0.5 g/L up to at maximum 21 g/L are considered. We use non-functionalized PS NPs as representative for mostly negatively charged nanoplastics. BSA promotes NP aggregation through adsorption onto the NPs and BSA-mediated bridging. In BSA–alginate mixtures, the alginate hampers this interaction, most likely due to alginate–BSA complex formation. In most BSA–alginate mixtures as in alginate alone, NP aggregation is predominantly driven by weaker, pH-independent depletion forces. The stabilizing effect of alginate is only weakened at high BSA contents, when the electrostatic BSA–BSA attraction is not sufficiently screened by the alginate. This study clearly shows that it is crucial to consider correlative effects between multiple biofilm components to better understand the NP aggregation in the presence of complex biofilm substances. Single-component biofilm model systems based on comparing the total organic carbon (TOC) content of the extracellular biofilm substances, as usually considered, would have led to a misjudgment of the stability towards aggregation. Full article
(This article belongs to the Section Polymer Physics and Theory)
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14 pages, 4427 KiB  
Article
Constructing Heterostructured MWCNT-BN Hybrid Fillers in Electrospun TPU Films to Achieve Superior Thermal Conductivity and Electrical Insulation Properties
by Yang Zhang, Shichang Wang, Hong Wu and Shaoyun Guo
Polymers 2024, 16(15), 2139; https://doi.org/10.3390/polym16152139 - 27 Jul 2024
Cited by 1 | Viewed by 1309
Abstract
The development of thermally conductive polymer/boron nitride (BN) composites with excellent electrically insulating properties is urgently demanded for electronic devices. However, the method of constructing an efficient thermally conductive network is still challenging. In the present work, heterostructured multi-walled carbon nanotube-boron nitride (MWCNT-BN) [...] Read more.
The development of thermally conductive polymer/boron nitride (BN) composites with excellent electrically insulating properties is urgently demanded for electronic devices. However, the method of constructing an efficient thermally conductive network is still challenging. In the present work, heterostructured multi-walled carbon nanotube-boron nitride (MWCNT-BN) hybrids were easily prepared using an electrostatic self-assembly method. The thermally conductive network of the MWCNT-BN in the thermoplastic polyurethane (TPU) matrix was achieved by the electrospinning and stack-molding process. As a result, the in-plane thermal conductivity of TPU composite films reached 7.28 W m−1 K−1, an increase of 959.4% compared to pure TPU films. In addition, the Foygel model showed that the MWCNT-BN hybrid filler could largely decrease thermal resistance compared to that of BN filler and further reduce phonon scattering. Finally, the excellent electrically insulating properties (about 1012 Ω·cm) and superior flexibility of composite film make it a promising material in electronic equipment. This work offers a new idea for designing BN-based hybrids, which have broad prospects in preparing thermally conductive composites for further practical thermal management fields. Full article
(This article belongs to the Special Issue Advance in Polymer Composites: Fire Protection and Thermal Management)
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16 pages, 5130 KiB  
Article
Mechanical and Insulation Performance of Rigid Polyurethane Foam Reinforced with Lignin-Containing Nanocellulose Fibrils
by Kabirat O. Bello and Ning Yan
Polymers 2024, 16(15), 2119; https://doi.org/10.3390/polym16152119 - 25 Jul 2024
Cited by 6 | Viewed by 2232
Abstract
Isocyanates are critical components that affect the crosslinking density and structure of polyurethane (PU) foams. However, due to the cost and hazardous nature of the precursor for isocyanate synthesis, there is growing interest in reducing their usage in polyurethane foam production—especially in rigid [...] Read more.
Isocyanates are critical components that affect the crosslinking density and structure of polyurethane (PU) foams. However, due to the cost and hazardous nature of the precursor for isocyanate synthesis, there is growing interest in reducing their usage in polyurethane foam production—especially in rigid PU foams (RPUF) where isocyanate is used in excess of the stoichiometric ratio. In this study, lignin-containing nanocellulose fibrils (LCNF) were explored as mechanical reinforcements for RPUF with the goal of maintaining the mechanical performance of the foam while using less isocyanate. Different amounts of LCNF (0–0.2 wt.%) were added to the RPUF made using isocyanate indices of 1.1, 1.05, 1.0, and 0.95. Results showed that LCNF served as a nucleating agent, significantly reducing cell size and thermal conductivity. LCNF addition increased the crosslinking density of RPUF, leading to enhanced compressive properties at an optimal loading of 0.1 wt.% compared to unreinforced foams at the same isocyanate index. Furthermore, at the optimal loading, LCNF-reinforced foams made at lower isocyanate indices showed comparable stiffness and strength to unreinforced foams made at higher isocyanate indices. These results highlight the reinforcing potential of LCNF in rigid polyurethane foams to improve insulation and mechanical performance with lower isocyanate usage. Full article
(This article belongs to the Special Issue Functional Bio-Based Polymers and Composites for Multipurpose Applications)
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16 pages, 1176 KiB  
Review
Advancements in Stone Object Restoration Using Polymer-Inorganic Phosphate Composites for Cultural Heritage Preservation
by Toma Fistos, Irina Fierascu, Doina Manaila-Maximean and Radu Claudiu Fierascu
Polymers 2024, 16(14), 2085; https://doi.org/10.3390/polym16142085 - 22 Jul 2024
Cited by 3 | Viewed by 1689
Abstract
Recent advancements in cultural heritage preservation have increasingly focused on the development and application of new composites, harnessing the diverse properties of their components. This study reviews the current state of research and practical applications of these innovative materials, emphasizing the use of [...] Read more.
Recent advancements in cultural heritage preservation have increasingly focused on the development and application of new composites, harnessing the diverse properties of their components. This study reviews the current state of research and practical applications of these innovative materials, emphasizing the use of inorganic phosphatic materials (in particular the hydroxyapatite) and various polymers. The compatibility of phosphatic materials with calcareous stones and the protective properties of polymers present a synergistic approach to addressing common deterioration mechanisms, such as salt crystallization, biological colonization, and mechanical weathering. By examining recent case studies and experimental results, this paper highlights the effectiveness, challenges, and future directions for these composites in cultural heritage conservation. The findings underscore the potential of these materials to enhance the durability and aesthetic integrity of heritage stones, promoting sustainable and long-term preservation solutions. Full article
(This article belongs to the Section Polymer Applications)
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16 pages, 4380 KiB  
Article
Atmospheric Plasma Treatment to Improve PHB Coatings on 316L Stainless Steel
by J. Radilla, H. Martínez, O. Vázquez and B. Campillo
Polymers 2024, 16(14), 2073; https://doi.org/10.3390/polym16142073 - 20 Jul 2024
Viewed by 1583
Abstract
In the present study, biopolymeric coatings of polyhydroxybutyrate (PHB) were deposited on 316L stainless steel substrates. The PHB coatings were developed using the spin coating method. To improve the adhesion of the PHB coating on the substrate, this method uses an atmospheric plasma [...] Read more.
In the present study, biopolymeric coatings of polyhydroxybutyrate (PHB) were deposited on 316L stainless steel substrates. The PHB coatings were developed using the spin coating method. To improve the adhesion of the PHB coating on the substrate, this method uses an atmospheric plasma treatment. Adhesion tests show a 156% increase in adhesion after 5 s of surface treatment. Raman spectroscopy analysis of the polymer shows the incorporation of functional groups and the formation of new hydrogen bonds, which can help us bind drugs and promote osteogenesis after plasma treatment. Additionally, the electrochemical behaviors in artificial body fluids (Hanks’ solution) of the PHB coatings on the steel were evaluated with potentiodynamic tests, which revealed a decrease in the corrosion current and resistance to the transfer of the charge from the electrolyte to the 316L steel because of the PHB coating. All the PHB coatings were characterized using scanning electron microscopy and Raman spectroscopy after the electrochemical tests. This analysis confirmed the diffusion of electrolyte species toward the surface and the degradation of the polymer chain for the first 15 s of treatment with atmospheric plasma. These findings support the claim that plasma surface modification is a quick, environmentally friendly, and cost-effective method to enhance the performance of PHB coatings on 316L stainless steel for medical devices. Full article
(This article belongs to the Special Issue Plasma Processing of Polymers, 2nd Edition)
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21 pages, 39792 KiB  
Review
Eco-Friendly Polymer Nanocomposite Coatings for Next-Generation Fire Retardants for Building Materials
by Haradhan Kolya and Chun-Won Kang
Polymers 2024, 16(14), 2045; https://doi.org/10.3390/polym16142045 - 17 Jul 2024
Cited by 6 | Viewed by 4526
Abstract
The increasing global commitment to carbon neutrality has propelled a heightened focus on sustainable construction materials, with wood emerging as pivotal due to its environmental benefits. This review explores the development and application of eco-friendly polymer nanocomposite coatings to enhance wood’s fire resistance, [...] Read more.
The increasing global commitment to carbon neutrality has propelled a heightened focus on sustainable construction materials, with wood emerging as pivotal due to its environmental benefits. This review explores the development and application of eco-friendly polymer nanocomposite coatings to enhance wood’s fire resistance, addressing a critical limitation in its widespread adoption. These nanocomposites demonstrate improved thermal stability and char formation properties by integrating nanoparticles, such as nano-clays, graphene oxide, and metal oxides, into biopolymer matrices. This significantly mitigates the flammability of wood substrates, creating a robust barrier against heat and oxygen. The review provides a comprehensive examination of these advanced coatings’ synthesis, characterization, and performance. By emphasizing recent innovations and outlining future research directions, this review underscores the potential of eco-friendly polymer nanocomposite coatings as next-generation fire retardants. This advancement supports the expanded utilization of wood in sustainable construction practices and aligns with global initiatives toward achieving carbon neutrality. Full article
(This article belongs to the Special Issue Advances in Functional Polymers and Composites)
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14 pages, 4710 KiB  
Article
Behavior of a Precast Bridge Pier with Basalt Fiber-Reinforced Polymer (BFRP)-Strengthened Segments under Seismic Loading
by Chao Li, Yaowei Peng, Pengyu Yang, Hao Zhou and Ningbo Wang
Polymers 2024, 16(14), 2018; https://doi.org/10.3390/polym16142018 - 15 Jul 2024
Viewed by 1145
Abstract
The precast segmental column (PSC) has been proposed for reducing onsite construction time and minimizing impacts on traffic and the environment. It has been proven to have good seismic performance according to previous studies. However, due to the rocking behavior of the column, [...] Read more.
The precast segmental column (PSC) has been proposed for reducing onsite construction time and minimizing impacts on traffic and the environment. It has been proven to have good seismic performance according to previous studies. However, due to the rocking behavior of the column, the toe of the bottom segment could experience excessive compressive damage. In addition, the commonly used steel rebars in the PSC could experience corrosion problems during the service life of the structure. Moreover, ordinary Portland cement concrete (OPC) is normally used in the construction of the PSC, but the manufacturing processes of the OPC could emit a lot of carbon dioxide. This paper investigates the seismic performance of PSCs incorporating Basalt Fiber Reinforced Polymer (BFRP) bars and geopolymer concrete (GPC) segments. To mitigate the concrete crushing damage of the segment, the BFRP sheet was used to wrap the bottom segment of one of the specimens. The results revealed that the BFRP-reinforced geopolymer concrete PSC exhibited good seismic performance with minimal damage and small residual displacement. Strengthening the bottom segment with BFRP wrapping proved to be effective in reducing concrete damage. As a result, the column with BFRP wrap demonstrated the ability to withstand ground motions with higher Peak Ground Acceleration (PGA) compared to the column without strengthening. Full article
(This article belongs to the Special Issue Processing, Characterization and Engineering Application of Fiber-Reinforced Thermoplastic Polymer Composites)
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13 pages, 5394 KiB  
Article
Natural Rubber/Styrene–Butadiene Rubber Blend Composites Potentially Applied in Damping Bearings
by Saifeng Tang, Zhanxu Li, Weichong Sun, Yangling Liu, Jian Wang, Xiong Wang and Jun Lin
Polymers 2024, 16(13), 1945; https://doi.org/10.3390/polym16131945 - 8 Jul 2024
Cited by 4 | Viewed by 2305
Abstract
Natural rubber (NR) composites have been widely applied in damping products to reduce harmful vibrations, while rubber with only a single composition barely meets performance requirements. In this study, rubber blend composites including various ratios of NR and styrene butadiene rubber (SBR) were [...] Read more.
Natural rubber (NR) composites have been widely applied in damping products to reduce harmful vibrations, while rubber with only a single composition barely meets performance requirements. In this study, rubber blend composites including various ratios of NR and styrene butadiene rubber (SBR) were prepared via the conventional mechanical blending method. The effects of the rubber components on the compression set, compression fatigue temperature rising and the thermal oxidative aging properties of the NR/SBR blend composites were investigated. Meanwhile, the dynamic mechanical thermal analyzer and rubber processing analyzer were used to characterize the dynamic viscoelasticity of the NR/SBR blend composites. It was shown that, with the increase in the SBR ratio, the vulcanization rate of the composites increased significantly, while the compression fatigue temperature rising of the composites decreased gradually from 47 °C (0% SBR ratio) to 31 °C (50% SBR ratio). The compression set of the composites remained at ~33% when the SBR ratio was no more than 20%, and increased gradually when the SBR ratio was more than 20%. Full article
(This article belongs to the Special Issue Polymers and Polymer Composites: Structure-Property Relationship, 2nd Edition)
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21 pages, 7872 KiB  
Article
Thermomechanical Material Characterization of Polyethylene Terephthalate Glycol with 30% Carbon Fiber for Large-Format Additive Manufacturing of Polymer Structures
by Katie A. Martin, Guillermo A. Riveros, Travis L. Thornell, Zackery B. McClelland, Elton L. Freeman and James T. Stinson
Polymers 2024, 16(13), 1913; https://doi.org/10.3390/polym16131913 - 4 Jul 2024
Cited by 4 | Viewed by 1906
Abstract
Large-format additive manufacturing (LFAM) is used to print large-scale polymer structures. Understanding the thermal and mechanical properties of polymers suitable for large-scale extrusion is needed for design and production capabilities. An in-house-built LFAM printer was used to print polyethylene terephthalate glycol with 30% [...] Read more.
Large-format additive manufacturing (LFAM) is used to print large-scale polymer structures. Understanding the thermal and mechanical properties of polymers suitable for large-scale extrusion is needed for design and production capabilities. An in-house-built LFAM printer was used to print polyethylene terephthalate glycol with 30% carbon fiber (PETG CF30%) samples for thermomechanical characterization. Thermogravimetric analysis (TGA) shows that the samples were 30% carbon fiber by weight. X-ray microscopy (XRM) and porosity studies find 25% voids/volume for undried material and 1.63% voids/volume for dry material. Differential scanning calorimetry (DSC) shows a glass transition temperature (Tg) of 66 °C, while dynamic mechanical analysis (DMA) found Tg as 82 °C. The rheology indicated that PETG CF30% is a good printing material at 220–250 °C. Bending experiments show an average of 48.5 MPa for flexure strength, while tensile experiments found an average tensile strength of 25.0 MPa at room temperature. Comparison with 3D-printed PLA and PETG from the literature demonstrated that LFAM-printed PETG CF30% had a comparative high Young’s modulus and had similar tensile strength. For design purposes, prints from LFAM should consider both material choice and print parameters, especially when considering large layer heights. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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