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Polymers
Volume 16
Issue 19
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Polymers, Volume 16, Issue 19 (October-1 2024) – 169 articles

Cover Story (view full-size image): Dual-responsive alginate/PNIPAM microspheres, responding to both pH and temperature variations, are developed for the controlled delivery of bioactive lipophilic compounds. The microspheres are fabricated using a microemulsion-based electrospray technique without the use of toxic solvents. A chitosan coating is added to improve stability and degradation control. DSC is used to assess the thermal response of the microspheres, while degradation assays at different values of pH and temperature unveil their dual-responsive behavior. This work offers a promising approach for the targeted delivery of Ozoile, stable ozonides derived from olive oil, particularly useful in the context of oxidative stress modulation and inflammation management. View this paper
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26 pages, 10742 KiB  
Article
Performance of Bamboo Bark Fiber Asphalt Mortar Modified with Surface-Grafted Nano-SiO2
by Nan Zhang, Xichen Wang, Pei Sun, Nanxiang Zheng and Aodi Sun
Polymers 2024, 16(19), 2850; https://doi.org/10.3390/polym16192850 - 9 Oct 2024
Viewed by 463
Abstract
In this study, the feasibility of using bamboo bark fibers as modifiers to enhance asphalt mortar performance was investigated. Bamboo bark fibers were modified with NaOH, KH570 silane coupling agent, and nano-SiO2, and their preparation methods were established. The modified fibers [...] Read more.
In this study, the feasibility of using bamboo bark fibers as modifiers to enhance asphalt mortar performance was investigated. Bamboo bark fibers were modified with NaOH, KH570 silane coupling agent, and nano-SiO2, and their preparation methods were established. The modified fibers were assessed for their oil absorption, thermal stability, and hydrophobicity. The asphalt mortar was evaluated for three key indicators: rutting resistance, deformation resistance, and durability at high temperatures. The microscopic morphology and modification mechanisms of the fibers were also studied. The results showed that modification with NaOH increased fiber porosity and surface roughness, while KH570 and its hydrolysis products enabled nano-SiO2 grafting onto the fibers, improving their adsorption to asphalt. The NaOH-KH570-nano-SiO2 ternary-composite-modified bamboo bark fiber (NKSBF) demonstrated superior hydrophobicity, oil absorption, and thermal stability at the asphalt mixing temperature. Among the modified fibers, asphalt mortar containing 3% NKSBF showed the best performance based on three key indicators, increased the shear strength by 96.4% and the softening point by 7.1% compared to the base asphalt, and increased the ductility by 1% compared to lignin fiber asphalt mortar. The incorporation of 3% bamboo bark fibers improved the rutting resistance, deformation resistance, and durability of short-term-aged asphalt mortar, with NKSBF showing the most significant improvement. Full article
(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites—3rd Edition)
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13 pages, 7145 KiB  
Article
Mechanical Performance of Cellulose Nanocrystal and Bioceramic-Based Composites for Surgical Training
by Hee-Chang Jeon and Young-Seong Kim
Polymers 2024, 16(19), 2849; https://doi.org/10.3390/polym16192849 - 9 Oct 2024
Viewed by 409
Abstract
This study evaluated the mechanical performance of a cellulose nanocrystal (CNC)-based composite, consisting of hydroxyapatite and natural fibers, mimicking the mechanical properties of real bone. The effect of natural nanofibers on the cutting force of the composite was evaluated for suitability in surgical [...] Read more.
This study evaluated the mechanical performance of a cellulose nanocrystal (CNC)-based composite, consisting of hydroxyapatite and natural fibers, mimicking the mechanical properties of real bone. The effect of natural nanofibers on the cutting force of the composite was evaluated for suitability in surgical training. Although hydroxyapatite has been extensively studied in bone-related applications, the exploration of epoxy-based composites incorporating both hydroxyapatite and CNC represents a novel approach. The evaluation involved a load cell with an oscillating saw. The uniform distribution of CNCs within the composite was assessed using 3D X-ray imaging. The cutting force was found to be 4.005 ± 0.5469 N at a feed rate of 0.5 mm/s, comparable to that required when cutting real bone with the osteon at 90°. The 90-degree orientation of the osteon aligns with the cutting direction of the oscillating saw when performing knee replacements on the tibia and femur bones. The addition of CNCs resulted in changes in fracture toughness, leading to increased material fragmentation and surface irregularities. Furthermore, the change in the cutting force with depth was similar to that of real bone. The developed composite material enables bone-cutting surgeries using bioceramics and natural fibers without the risks associated with cadavers or synthetic fibers. Mold-based computed tomography data allows for the creation of various bone forms, enhancing skill development for surgeons. Full article
(This article belongs to the Special Issue Advanced Epoxy-Based Materials, 5th Edition)
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29 pages, 5705 KiB  
Review
A Review of Green Aerogel- and Xerogel-Based Electrodes for Supercapacitors
by Ngo Tran, Hyung Wook Choi and Quang Nhat Tran
Polymers 2024, 16(19), 2848; https://doi.org/10.3390/polym16192848 - 9 Oct 2024
Viewed by 675
Abstract
The decline in fossil fuels on the earth has become a primary global concern which has urged mankind to explore other viable alternatives. The exorbitant use of fuels by an ever-increasing global population demands a huge production of energy from renewable sources. Renewable [...] Read more.
The decline in fossil fuels on the earth has become a primary global concern which has urged mankind to explore other viable alternatives. The exorbitant use of fuels by an ever-increasing global population demands a huge production of energy from renewable sources. Renewable energy sources like the sun, wind, and tides have been established as promising substitutes for fossil fuels. However, the availability of these renewable energy sources is dependent on weather and climatic conditions. Thus, this goal can only be achieved if the rate of energy production from renewable sources is enhanced under favorable weather conditions and can be stored using high energy storing devices for future utilization. The energy from renewable sources is principally stored in hydropower plants, superconducting magnetic energy storage systems, and batteries. Full article
(This article belongs to the Special Issue Advances in Multifunctional Polymer-Based Nanocomposites II)
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15 pages, 1765 KiB  
Article
Benefits of Environmentally Friendly Plaster on Mechanical Properties When Combined with Polyester Resin and Hardener Are Examined under Compression and Tension
by Mohammed A. Albadrani and Ahmed D. Almutairi
Polymers 2024, 16(19), 2847; https://doi.org/10.3390/polym16192847 - 9 Oct 2024
Viewed by 433
Abstract
Recently, plaster has gained increasing attention as a mechanical and environmentally friendly option and is an effective alternative to traditional cement products. Additionally, polyester has an effective impact on the mechanical properties of materials, in addition to being one of the most environmentally [...] Read more.
Recently, plaster has gained increasing attention as a mechanical and environmentally friendly option and is an effective alternative to traditional cement products. Additionally, polyester has an effective impact on the mechanical properties of materials, in addition to being one of the most environmentally friendly materials. However, studies are still ongoing to reach the best ratios of polyester resin, polyester hardener, and gypsum plaster that can improve mechanical properties. This research aims to investigate the impact of these components at various ratios (30%, 45%, and 60%) of gypsum plaster weight on the mechanical properties of plaster material. This study is carried out by conducting compression and tensile tests for three ratios, which are considered among the most important mechanical tests according to their applications. In addition, the environmental emissions resulting from the three different ratios of plaster are evaluated to determine their environmental impact. This study found that the largest ratio (30%) was the most effective from an economic and mechanical point of view, while achieving lower carbon emissions compared to the other ratios, which enhances the trend towards achieving the environmental goals of the Kingdom of Saudi Arabia’s Vision 2030 to reach zero emissions. This study is highly significant both in terms of scientific research and practical application across a range of industries, since it integrates the enhancement of material performance with the achievement of environmental sustainability requirements. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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19 pages, 21000 KiB  
Article
Synthesis of a Novel Zwitterionic Hypercrosslinked Polymer for Highly Efficient Iodine Capture from Water
by Jingwen Yu, Luna Song, Bingying Han, Jiangliang Hu, Zhong Li and Jie Mi
Polymers 2024, 16(19), 2846; https://doi.org/10.3390/polym16192846 - 9 Oct 2024
Viewed by 424
Abstract
Cationic porous organic polymers have a unique advantage in removing radioactive iodine from the aqueous phase because iodine molecules exist mainly in the form of iodine-containing anions. However, halogen anions will inevitably be released into water during the ion-exchange process. Herein, we reported [...] Read more.
Cationic porous organic polymers have a unique advantage in removing radioactive iodine from the aqueous phase because iodine molecules exist mainly in the form of iodine-containing anions. However, halogen anions will inevitably be released into water during the ion-exchange process. Herein, we reported a novel and easy-to-construct zwitterionic hypercrosslinked polymer (7AIn-PiP)-containing cationic pyridinium-type group, uncharged pyridine-type group, pyrrole-type group, and even an electron-rich phenyl group, which in synergy effectively removed 94.2% (456 nm) of I2 from saturated I2 aqueous solution within 30 min, surpassing many reported iodine adsorbents. Moreover, an I2 adsorption efficiency of ~95% can still be achieved after three cyclic evaluations, indicating a good recycling performance. More importantly, a unique dual 1,3-dipole was obtained and characterized by 1H/13C NMR, HRMS, and FTIR, correlating with the structure of 7AIn-PiP. In addition, the analysis of adsorption kinetics and the characterization of I2@7AIn-PiP indicate that the multiple binding sites simultaneously contribute to the high affinity towards iodine species by both physisorption and chemisorption. Furthermore, an interesting phenomenon of inducing the formation of HIO2 in unsaturated I2 aqueous solution was discovered and explained. Overall, this work is of great significance for both material and radiation protection science. Full article
(This article belongs to the Special Issue Resilient Polymer Materials: Reduce the Risks and Effects of Natural Disasters)
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22 pages, 12585 KiB  
Article
Preparation and Characterization of Atomic Oxygen-Resistant, Optically Transparent and Dimensionally Stable Copolyimide Films from Fluorinated Monomers and POSS-Substituted Diamine
by Zhenzhong Wang, Xiaolei Wang, Shunqi Yuan, Xi Ren, Changxu Yang, Shujun Han, Yuexin Qi, Duanyi Li and Jingang Liu
Polymers 2024, 16(19), 2845; https://doi.org/10.3390/polym16192845 - 9 Oct 2024
Viewed by 466
Abstract
Optically transparent polyimide (PI) films with good atomic oxygen (AO) resistance have been paid extensive attention as thermal controls, optical substrates for solar cells or other components for low Earth orbit (LEO) space applications. However, for common PI films, it is usually quite [...] Read more.
Optically transparent polyimide (PI) films with good atomic oxygen (AO) resistance have been paid extensive attention as thermal controls, optical substrates for solar cells or other components for low Earth orbit (LEO) space applications. However, for common PI films, it is usually quite difficult to achieve both high optical transparency and AO resistance and maintain the intrinsic thermal stability of the PI films at the same time. In the current work, we aimed to achieve the target by using the copolymerization methodology using the fluorinated dianhydride 9,9-bis(trifluoromethyl)xanthene-2,3,6,7-tetracarboxylic dianhydride (6FCDA), the fluorinated diamine 2,2-bis [4-(4-aminophenoxy)phenyl]hexafluoropropane (BDAF) and the polyhedral oligomeric silsesquioxane (POSS)-containing diamine N-[(heptaisobutyl-POSS)propyl]-3,5-diaminobenzamide (DABA-POSS) as the starting materials. The fluoro-containing monomers were used to endow the PI films with good optical and thermal properties, while the silicon-containing monomer was used to improve the AO resistance of the afforded PI films. Thus, the 6FCDA-based PI copolymers, including 6FCPI-1, 6FCPI-2 and 6FCPI-3, were prepared using a two-step chemical imidization procedure, respectively. For comparison, the analogous PIs, including 6FPI-1, 6FPI-2 and 6FPI-3, were correspondingly developed according to the same procedure except that 6FCDA was replaced by 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA). Two referenced PI homopolymers were prepared from BDAF and 6FDA (PI-ref1) and 6FCDA (PI-ref2), respectively. The experimental results indicated that a good balance among thermal stability, optical transparency, and AO resistance was achieved by the 6FCDA-PI films. For example, the 6FCDA-PI films exhibited good thermal stability with glass transition temperatures (Tg) up to 297.3 °C, good optical transparency with an optical transmittance at a wavelength of 450 nm (T450) higher than 62% and good AO resistance with the erosion yield (Ey) as low as 1.7 × 10−25 cm3/atom at an AO irradiation fluence of 5.0 × 1020 atoms/cm2. The developed 6FCDA-PI films might find various applications in aerospace as solar sails, thermal control blankets, optical components and other functional materials. Full article
(This article belongs to the Special Issue Polymer Thin Films and Their Applications)
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79 pages, 569 KiB  
Conference Report
Abstracts of the 2024 50th Annual NATAS Conference
by Rigoberto Advincula, Christopher Bowman, Dennis Smith, Karl Schoch, Jr., Tina Adams, Cathy Stewart, Lawrence Judovits and Louis Pilato
Polymers 2024, 16(19), 2844; https://doi.org/10.3390/polym16192844 - 8 Oct 2024
Viewed by 662
Abstract
The 50th annual conference of the North American Thermal Analysis Society is being held jointly with the 8th Baekeland Symposium to bring those communities together. NATAS offers scientists and practitioners the opportunity to explore the frontiers of thermal analysis, rheology, and materials characterization, [...] Read more.
The 50th annual conference of the North American Thermal Analysis Society is being held jointly with the 8th Baekeland Symposium to bring those communities together. NATAS offers scientists and practitioners the opportunity to explore the frontiers of thermal analysis, rheology, and materials characterization, learn of developments in instrumentation and software, as well as applications in a variety of industrial settings. The Baekeland Symposium has a record of showcasing the latest scientific, technical and industrial innovations in the field of high performance thermosetting polymers. This year is the first joint meeting of the two organizations and is expected to provide opportunities for new collaborations and exchange of ideas. Presentations and posters by renowned scientists and graduate students set the stage for excellent discussions and an ideal environment to learn about state-of-the-art techniques and exciting new developments in thermal analysis and materials research. Full article
(This article belongs to the Special Issue State-of-the-Art Thermal Properties and Applications of Polymers)
13 pages, 3768 KiB  
Article
Performance of Recycled Opaque PET Modified by Reactive Extrusion
by Noel León-Albiter, Orlando O. Santana, Leandro Martinez Orozco, Nicolas Candau and Maria Lluïsa Maspoch
Polymers 2024, 16(19), 2843; https://doi.org/10.3390/polym16192843 - 8 Oct 2024
Viewed by 399
Abstract
A comparative study of the structural integrity of an opaque recycled poly(ethylene terephthalate) (rPET-O) has been carried out with two types of modified rPET-O by applying reactive extrusion techniques, namely (a) using a multi-epoxide reactive agent (REx-rPET-O) and (b) a 90/10 (wt/wt) rPET-O/polycarbonate [...] Read more.
A comparative study of the structural integrity of an opaque recycled poly(ethylene terephthalate) (rPET-O) has been carried out with two types of modified rPET-O by applying reactive extrusion techniques, namely (a) using a multi-epoxide reactive agent (REx-rPET-O) and (b) a 90/10 (wt/wt) rPET-O/polycarbonate (PC) blend. The chemical modifications introduced during reactive extrusion were confirmed using differential scanning calorimetry (DSC) and rheological dynamic analysis (RDA). For the quantification of the fracture parameters, an instrumented pendulum impact testing machine was used using specimens in SENB configuration. The structural modifications generated during reactive extrusion promote an increase of between 16 (REx-rPET-O) and 20% (rPET-O/PC) in the stress-intensity factor (KQ) compared to unmodified rPET-O. The most significant differences between both modifications are registered in the “specific work of fracture” (wf) (alternative parameter to the standardized impact strength), where an increase of 61% is reached for the case of rPET-O/PC and only 11% for REx-rPET-O. This trend can be attributed to the type of reactive modification that is generated, namely chain branching (REx-rPET-O) vs. the generation of a random copolymer “in situ” (rPET-O/PC). This copolymer decreases the crystallization capacity and degree of crystalline perfection of rPET-O, promoting an increase in the critical hydrostatic stress conditions for the generation of crazing and crack propagation. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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9 pages, 1769 KiB  
Communication
Preparation of Antimicrobial Agents: From Interpolyelectrolyte Complexes to Silver-Containing Metal–Polymer Complexes and Nanocomposites
by Dmitry I. Klimov, Alexey A. Zharikov, Elena A. Zezina, Elena A. Kotenkova, Elena V. Zaiko, Dagmara S. Bataeva, Anastasia A. Semenova, Yulia K. Yushina, Aleksander A. Yaroslavov and Alexey A. Zezin
Polymers 2024, 16(19), 2842; https://doi.org/10.3390/polym16192842 (registering DOI) - 8 Oct 2024
Viewed by 452
Abstract
In order to control pathogenic microorganisms, three polymer compositions were prepared and tested. First, a water-soluble positively charged polycomplex was synthesized via the electrostatic binding of anionic polyacrylic acid to an excess of polyethylenimine to enhance the biocidal activity of the polycation. Second, [...] Read more.
In order to control pathogenic microorganisms, three polymer compositions were prepared and tested. First, a water-soluble positively charged polycomplex was synthesized via the electrostatic binding of anionic polyacrylic acid to an excess of polyethylenimine to enhance the biocidal activity of the polycation. Second, an aqueous solution of AgNO3 was added to the polycomplex, thus forming a ternary polycation-polyanion-Ag1+ complex with an additional antimicrobial effect. Third, the resulting ternary complex was subjected to UV irradiation, which ensured the conversion of Ag1+ ions into Ag nanoparticles ranging in size mainly from 10 to 20 nm. Aqueous solutions of the polymer compositions were added to suspensions of the Gram-positive bacteria S. aureus and the Gram-negative bacteria P. aeruginosa, with the following main results: (a) Upon the addition of the binary polycomplex, 30% or more of the cells survived after 20 h. (b) The ternary complex killed S. aureus bacteria but was ineffective against P. aeruginosa bacteria. (c) When the ternary complex with Ag nanoparticles was added, the percentage of surviving cells of both types did not exceed 0.03%. The obtained results are valuable for the development of antibacterial formulations. Full article
(This article belongs to the Special Issue Synthesis and Applications of Polymer-Based Nanocomposites)
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16 pages, 3057 KiB  
Article
The Role of Formulations in the Ageing Process of Vinyl Acetate Based Emulsion Films: A Multivariate Approach
by Carolina Viana, Karin Wieland, Susana França de Sá, Eva Mariasole Angelin, Valentina Pintus and Joana Lia Ferreira
Polymers 2024, 16(19), 2841; https://doi.org/10.3390/polym16192841 - 8 Oct 2024
Viewed by 442
Abstract
Vinyl acetate (VAc)-based emulsions represent one of the main media used by modern and contemporary artists. Their long-term behaviour is still not completely understood, especially due to the scarce knowledge on the influence of other compounds in the formulation, which may impact ageing [...] Read more.
Vinyl acetate (VAc)-based emulsions represent one of the main media used by modern and contemporary artists. Their long-term behaviour is still not completely understood, especially due to the scarce knowledge on the influence of other compounds in the formulation, which may impact ageing over time. Besides the polymer backbone based on vinyl acetate, other co-monomers and additives can be added to the emulsion to alter the final film’s physical, chemical, and optical properties. By extension, the formulation will also impact the long-term stability of artworks and objects on which it has been applied, as well as possible current and future conservation interventions such as cleaning. For those reasons, studies shedding light on the correlation between composition and long-term stability are largely necessary. In this study, different emulsions, including homopolymers, copolymers, plasticised, and un-plasticised compositions, were gathered and artificially aged. A multivariate analyses approach based on the application of principal component analyses (PCA) and hierarchical cluster analyses (HCA) was employed for the first time on the combination of data obtained by pH, contact angle (CA), colour measurements, Fourier transform infrared spectroscopy in attenuated total reflection (FTIR-ATR), and size exclusion chromatography (SEC). This approach helped to highlight the changes that occurred during ageing and find correlations with the formulation compositions. The results further sustain the thesis that not all vinyl acetate-based emulsions are chemically the same and that their formulation deeply impacts their long-term behaviour. Full article
(This article belongs to the Section Polymer Analysis and Characterization)
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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
Viewed by 1061
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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21 pages, 4106 KiB  
Article
An Investigation of the Mechanical Properties of Flax/Basalt Epoxy Hybrid Composites from a Sustainability Perspective
by Martina Panico, Ersilia Cozzolino, Ilaria Papa, Iman Taha and Valentina Lopresto
Polymers 2024, 16(19), 2839; https://doi.org/10.3390/polym16192839 - 8 Oct 2024
Viewed by 600
Abstract
Currently, sustainability plays a central role in the response to global challenges, strongly influencing decisions in various sectors. From this perspective, global efforts to explore inventive and eco-friendly solutions to address the demands of industrialization and large-scale production are being made. Bio-based composites [...] Read more.
Currently, sustainability plays a central role in the response to global challenges, strongly influencing decisions in various sectors. From this perspective, global efforts to explore inventive and eco-friendly solutions to address the demands of industrialization and large-scale production are being made. Bio-based composites needed for lightweight applications benefit from the integration of natural fibers, due to their lower specific weight compared to synthetic fibers, contributing to the overall reduction in the weight of such structures without compromising the mechanical performance. Nevertheless, challenges arise when using natural fibers in composite laminates and hybridization seems to be a solution. However, there is still a lack of knowledge in the literature regarding the strategies and possibilities for reducing laminate thickness, without sacrificing the mechanical performance. This work aims to fill this knowledge gap by investigating the possibility of reducing the laminate thickness in hybrid flax/basalt composites made of plies, organized in the same stacking sequence, through only varying their number. Tensile, Charpy, flexural, and drop-weight tests were carried out for the mechanical characterization of the composites. The results obtained confirm the feasibility of achieving thinner hybrid composites, thus contributing to sustainability, while still having acceptable mechanical properties for structural applications. Full article
(This article belongs to the Special Issue Natural Fiber-Based Green Materials)
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11 pages, 1673 KiB  
Article
Methallylsulfonate Polymeric Antiscalants for Application in Thermal Desalination Processes
by Ali A. Al-Hamzah, Christopher M. Fellows and Osman A. Hamed
Polymers 2024, 16(19), 2838; https://doi.org/10.3390/polym16192838 - 8 Oct 2024
Viewed by 498
Abstract
Nine copolymers of acrylic acid and sodium methallyl sulfonate were tested as scale inhibitors in thermal desalination. The nine antiscalants covered molar masses between 2000 and 9500 g.mol–1 and concentrations of sulfonated monomer ranging between 10 and 30 mole percent. A pressure [...] Read more.
Nine copolymers of acrylic acid and sodium methallyl sulfonate were tested as scale inhibitors in thermal desalination. The nine antiscalants covered molar masses between 2000 and 9500 g.mol–1 and concentrations of sulfonated monomer ranging between 10 and 30 mole percent. A pressure measurement and control (P-MAC) unit and a high-temperature pressurized vessel were used to measure the effectiveness of the scale inhibitors in seawater, concentrated seawater, and model solutions at 125 °C. The effectiveness of the novel copolymers was comparable to commercial antiscalant at times up to 15 min and improved at longer times. Molar mass was a more important determinant of effectiveness than degree of sulfonation, with the greatest mitigation of calcium sulfate precipitation observed for antiscalants of molar mass 2000 to 2500 g.mol–1 regardless of sulfonate content. Antiscalants of molar mass 4500 to 5000 g.mol–1 showed a higher threshold effect than antiscalants of molar mass 7000 to 9500 g.mol–1, with a 30% sulfonated polymer of molar mass 4500 g.mol–1 performing appreciably better than other polymers of a similar molar mass. Full article
(This article belongs to the Special Issue Recent Advances in Functional Polymer Materials for Water Treatment)
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33 pages, 5391 KiB  
Review
Micro-Nanoparticle Characterization: Establishing Underpinnings for Proper Identification and Nanotechnology-Enabled Remediation
by Wesley Allen Williams and Shyam Aravamudhan
Polymers 2024, 16(19), 2837; https://doi.org/10.3390/polym16192837 - 8 Oct 2024
Viewed by 687
Abstract
Microplastics (MPLs) and nanoplastics (NPLs) are smaller particles derived from larger plastic material, polymerization, or refuse. In context to environmental health, they are separated into the industrially-created “primary” category or the degradation derivative “secondary” category where the particles exhibit different physiochemical characteristics that [...] Read more.
Microplastics (MPLs) and nanoplastics (NPLs) are smaller particles derived from larger plastic material, polymerization, or refuse. In context to environmental health, they are separated into the industrially-created “primary” category or the degradation derivative “secondary” category where the particles exhibit different physiochemical characteristics that attenuate their toxicities. However, some particle types are more well documented in terms of their fate in the environment and potential toxicological effects (secondary) versus their industrial fabrication and chemical characterization (primary). Fourier Transform Infrared Spectroscopy (FTIR/µ-FTIR), Raman/µ-Raman, Proton Nuclear Magnetic Resonance (H-NMR), Curie Point-Gas Chromatography-Mass Spectrometry (CP-gc-MS), Induced Coupled Plasma-Mass Spectrometry (ICP-MS), Nanoparticle Tracking Analysis (NTA), Field Flow Fractionation-Multiple Angle Light Scattering (FFF-MALS), Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), Differential Mobility Particle [Sizing] (DMPS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Scanning Transmission X-ray Microspectroscopy (STXM) are reviewed as part of a suite of characterization methods for physiochemical ascertainment and distinguishment. In addition, Optical-Photothermal Infrared Microspectroscopy (O-PTIR), Z-Stack Confocal Microscopy, Mueller Matrix Polarimetry, and Digital Holography (DH) are touched upon as a suite of cutting-edge modes of characterization. Organizations, like the water treatment or waste management industry, and those in groups that bring awareness to this issue, which are in direct contact with the hydrosphere, can utilize these techniques in order to sense and remediate this plastic polymer pollution. The primary goal of this review paper is to highlight the extent of plastic pollution in the environment as well as introduce its effect on the biodiversity of the planet while underscoring current characterization techniques in this field of research. The secondary goal involves illustrating current and theoretical avenues in which future research needs to address and optimize MPL/NPL remediation, utilizing nanotechnology, before this sleeping giant of a problem awakens. Full article
(This article belongs to the Special Issue Micro- and Nanoplastics Engineering and Design for Research)
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13 pages, 1932 KiB  
Article
A Novel Plasma-Enhanced Solvolysis as Alternative for Recycling Composites
by Dimitrios Marinis, Dionysios Markatos, Ergina Farsari, Eleftherios Amanatides, Dimitrios Mataras and Spiros Pantelakis
Polymers 2024, 16(19), 2836; https://doi.org/10.3390/polym16192836 - 7 Oct 2024
Viewed by 442
Abstract
In this work, a plasma-assisted solvolysis method is proposed as an alternative method for the oxidative degradation of carbon fiber-reinforced composites (CFRCs). Nitrogen plasma ignition within bubbles in a concentrated nitric acid solution is employed, combining the synergistic effects of traditional nitric acid [...] Read more.
In this work, a plasma-assisted solvolysis method is proposed as an alternative method for the oxidative degradation of carbon fiber-reinforced composites (CFRCs). Nitrogen plasma ignition within bubbles in a concentrated nitric acid solution is employed, combining the synergistic effects of traditional nitric acid solvolysis and plasma chemistry. A comprehensive process flowchart, including steps such as composite pretreatment, matrix dissolution, fiber recovery and cleaning, solvent regeneration and reuse, and waste treatment, is also discussed, highlighting their importance in process effectiveness. Moreover, a study on the effect of the composite’s mass on the plasma-enhanced solvolysis process is conducted, and the results are exploited for the calculation of critical parameters such as efficiency, recovery rates, capacity, fibers quality, energy consumption, consumption of raw materials, operational and installation costs, and environmental impact. A preliminary comparison to other recycling methods based on the literature findings is also attempted, and preliminary metrics to assess the sustainability of the recycling process are proposed. Full article
(This article belongs to the Special Issue Smart and Intelligent Composite Structures for Innovative Industrial and Space Applications: Fiber-Reinforced Polymer Composites)
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20 pages, 3103 KiB  
Article
Polymers Containing Diethylsiloxane Segment and Active Functional Group by Ring-Opening Polymerization of Hexaethylcyclotrisiloxane under the Catalysis of Linear Chlorinated Phosphazene Acid
by Chen Jin, Hao Yang, Yang Zhang, Shuting Zhang, Xu Long, Hong Dong, Yanjiang Song, Zhirong Qu and Chuan Wu
Polymers 2024, 16(19), 2835; https://doi.org/10.3390/polym16192835 - 7 Oct 2024
Viewed by 572
Abstract
Linear chlorinated phosphazene acid is prepared using PCl5 and NH4Cl as raw materials. Using hexaethylcyclotrisiloxane as the monomer, 1,1,3,3-tetramethyldisiloxane or 1,3-divinyl-1,1,3,3-tetramethyldisiloxane as the end-capping agent, and linear chlorinated phosphazene acid as the catalyst, polydiethylsiloxane oligomers terminated with active Si-H or [...] Read more.
Linear chlorinated phosphazene acid is prepared using PCl5 and NH4Cl as raw materials. Using hexaethylcyclotrisiloxane as the monomer, 1,1,3,3-tetramethyldisiloxane or 1,3-divinyl-1,1,3,3-tetramethyldisiloxane as the end-capping agent, and linear chlorinated phosphazene acid as the catalyst, polydiethylsiloxane oligomers terminated with active Si-H or Si-CH=CH2 groups have been prepared. Using hexaethylcyclotrisiloxane and 1,3,5,7-octamethylcyclotetrasiloxane as comonomers, 1,1,3,3-tetramethyldisiloxane or hexamethyldisiloxane as the end-capping agent, or using hexaethylcyclotrisiloxane and octamethylcyclotetrasiloxane as comonomers, 1,1,3,3-tetramethyldisiloxane as the end-capping agent, copolymers containing active Si-H bonds and dimethylsiloxane segments have been prepared under the catalysis of linear chlorinated phosphazene acid. The effects of catalyst dosage, reaction temperature, reaction time, end-capping agent, and polymerization monomer dosage on polymer yield and structure were investigated. Using 300 ppm of linear chlorinated phosphazene acid, oligomers and copolymers containing an active Si-H bond and diethylsiloxane segment were prepared under mild conditions. The molecular weight of the obtained polymers was close to their designed values, but their PDI values were small. The highest yield of α, ω-bisdimethylsiloxyl-terminated PDES oligomers reached 93%. Using oligomers and copolymers containing Si-H bonds and diethylsiloxane segments as crosslinkers, a silicone gel containing diethylsiloxane segments was prepared by hydrosilylation reaction. With the introduction of a diethylsiloxane segment, the glass transition temperature of the silicone gel decreased relative to that of the PDMS oligomer, but the temperature at 5% weight loss in nitrogen atmosphere decreased from 347 °C to 312 °C. The mechanism of the ring-opening polymerization of hexaethylcyclotrisiloxane catalyzed by linear chlorinated phosphazene acid is also discussed. Full article
(This article belongs to the Section Polymer Chemistry)
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24 pages, 3637 KiB  
Article
Stabilization of Picea abies Spruce Bark Extracts within Ice-Templated Porous Dextran Hydrogels
by Roxana Petronela Damaschin, Maria Marinela Lazar, Claudiu-Augustin Ghiorghita, Ana Clara Aprotosoaie, Irina Volf and Maria Valentina Dinu
Polymers 2024, 16(19), 2834; https://doi.org/10.3390/polym16192834 - 7 Oct 2024
Viewed by 649
Abstract
Porous hydrogels have brought more advantages than conventional hydrogels when used as chromatographic materials, controlled release vehicles for drugs and proteins, matrices for immobilization or separation of molecules and cells, or as scaffolds in tissue engineering. Polysaccharide-based porous hydrogels, in particular, can address [...] Read more.
Porous hydrogels have brought more advantages than conventional hydrogels when used as chromatographic materials, controlled release vehicles for drugs and proteins, matrices for immobilization or separation of molecules and cells, or as scaffolds in tissue engineering. Polysaccharide-based porous hydrogels, in particular, can address challenges related to bioavailability, solubility, stability, and targeted delivery of natural antioxidant compounds. Their porous structure enables the facile encapsulation and controlled release of these compounds, enhancing their therapeutic effectiveness. In this context, in the present study, the cryogelation technique has been adopted to prepare novel dextran (Dx)-based porous hydrogels embedding polyphenol-rich natural extract from Picea abies spruce bark (SBE). The entrapment of the SBE within the Dx network was proved by FTIR, SEM, and energy-dispersive X-ray spectroscopy (EDX). SEM analysis showed that entrapment of SBE resulted in denser cryogels with smaller and more uniform pores. Swelling kinetics confirmed that higher concentrations of Dx, EGDGE, and SBE reduced water uptake. The release studies demonstrated the effective stabilization of SBE in the Dx-based cryogels, with minimal release irrespective of the approach selected for SBE incorporation, i.e., during synthesis (~3–4%) or post-synthesis (~15–16%). In addition, the encapsulation of SBE within the Dx network endowed the hydrogels with remarkable antioxidant and antimicrobial properties. These porous biomaterials could have broad applications in areas such as biomedical engineering, food preservation, and environmental protection, where stability, efficacy, and safety are paramount. Full article
(This article belongs to the Special Issue Drug-Loaded Polymer Colloidal Systems in Nanomedicine III)
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21 pages, 6481 KiB  
Article
In Situ Formation of Acidic Comonomer during Thermal Treatment of Copolymers of Acrylonitrile and Its Influence on the Cyclization Reaction
by Roman V. Toms, Daniil A. Ismaylov, Alexander Yu. Gervald, Nickolay I. Prokopov, Anna V. Plutalova and Elena V. Chernikova
Polymers 2024, 16(19), 2833; https://doi.org/10.3390/polym16192833 - 7 Oct 2024
Viewed by 594
Abstract
Binary and ternary copolymers of acrylonitrile (AN), tert-butyl acrylate (TBA), and n-butyl acrylate (BA) are synthesized through conventional radical polymerization in DMSO in the presence of 2-mercaptoethanol. The thermal behavior of binary and ternary copolymers is studied under argon atmosphere and [...] Read more.
Binary and ternary copolymers of acrylonitrile (AN), tert-butyl acrylate (TBA), and n-butyl acrylate (BA) are synthesized through conventional radical polymerization in DMSO in the presence of 2-mercaptoethanol. The thermal behavior of binary and ternary copolymers is studied under argon atmosphere and in air. It is demonstrated that the copolymers of AN contain 1–10 mol.% of TBA split isobutylene upon heating above 160 °C, resulting in the formation of the units of acrylic acid in the chain. The carboxylic groups formed in situ are responsible for the ionic mechanism of cyclization, which starts at lower temperatures compared with pure polyacrylonitrile (PAN) or AN copolymer with BA. The activation energy of cyclization through ionic and radical mechanisms depends on copolymer composition. For the ionic mechanism, the activation energy lies in the range ca. 100–130 kJ/mole, while for the radical mechanism, it lies in the range ca. 150–190 kJ/mole. The increase in the TBA molar part in the copolymer is followed by faster consumption of nitrile groups and the evolution of a ladder structure in both binary and ternary copolymers. Thus, the incorporation of a certain amount of TBA in PAN or its copolymer with BA allows tuning the temperature range of cyclization. This feature seems attractive for applications in the production of melt-spun PAN by choosing the appropriate copolymer composition and heating mode. Full article
(This article belongs to the Special Issue Advanced Polymer Materials: Synthesis, Structure, and Properties)
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21 pages, 10146 KiB  
Article
Evaluating the Effectiveness of Cellulose-Based Surfactants in Expandable Graphite Wood Coatings
by Tereza Jurczyková, Elena Kmeťová, František Kačík, Martin Lexa and Daniel Dědič
Polymers 2024, 16(19), 2832; https://doi.org/10.3390/polym16192832 - 7 Oct 2024
Viewed by 667
Abstract
This study deals with the design of modern environmentally friendly and non-toxic flame retardants based on expandable graphite 25 K + 180 (EG) modified by cellulose ethers (Lovose TS 20, Tylose MH 300, Klucel H) and nanocellulose (CNC) that are biocompatible with wood [...] Read more.
This study deals with the design of modern environmentally friendly and non-toxic flame retardants based on expandable graphite 25 K + 180 (EG) modified by cellulose ethers (Lovose TS 20, Tylose MH 300, Klucel H) and nanocellulose (CNC) that are biocompatible with wood and, therefore, are a prerequisite for an effective surfactant for connecting EG to wood. The effectiveness of the formulations and surfactants was verified using a radiant heat source test. The cohesion of the coating to the wood surface and the cohesion of the expanded graphite layer were also assessed. The fire efficiency of the surfactants varied greatly. Still, in combination with EG, they were all able to provide sufficient protection—the total relative mass loss was, in all cases, in the range of 7.38–7.83% (for untreated wood it was 88.67 ± 1.33%), and the maximum relative burning rate decreased tenfold compared to untreated wood, i.e., to 0.04–0.05%·s−1. Good results were achieved using Klucel H + EG and CNC + EG formulations. Compared to Klucel H, CNC provides significantly better cohesion of the expanded layer, but its high price increases the cost of the fireproof coating. Full article
(This article belongs to the Special Issue Wood and Wood-Based Composites: New Frontiers in Modification, Performance, and Sustainability)
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15 pages, 6043 KiB  
Article
Efficacy of Acacia Gum Biopolymer in Strength Improvement of Silty and Clay Soils under Varying Curing Conditions
by Muralidaran Vishweshwaran, Evangelin Ramani Sujatha, Ateekh Ur Rehman and Arif Ali Baig Moghal
Polymers 2024, 16(19), 2831; https://doi.org/10.3390/polym16192831 - 7 Oct 2024
Viewed by 678
Abstract
Acacia gum (AG), a polysaccharide biopolymer, has been adopted to improve the strength of three cohesive soils by subjecting them to diverse environmental aging conditions. Being a polysaccharide and a potentially sustainable construction material, the AG yielded flexible film-like threads after 48 h [...] Read more.
Acacia gum (AG), a polysaccharide biopolymer, has been adopted to improve the strength of three cohesive soils by subjecting them to diverse environmental aging conditions. Being a polysaccharide and a potentially sustainable construction material, the AG yielded flexible film-like threads after 48 h upon hydration, and its pH value of 4.9 varied marginally with the aging of the stabilized soils. The soil samples for the geotechnical evaluation were subjected to wet mixing and were tested under their Optimum Moisture Content (OMC), as determined by the light compaction method. The addition of AG modified the consistency indices of the soils due to the presence of hydroxyl groups in AG, which also led to a rise in OMC and reduction in Maximum Dry Unit weight (MDU). The Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) were determined under thermal curing at 333 K as well as on the same day of sample preparation. The least performing condition of the soil’s CBR was evaluated under submerged conditions after allowing the AG-stabilized specimens to air-cure for a period of 1 week. The UCS specimens tested after 7 days were subjected to the initial 7 days of thermal curing at 333 K. A dosage of 1.5% of AG yielded the UCS of 2530 kN/m2 and CBR of 98.3%, respectively, for the low compressible clay (LCC) after subjecting the sample to 333 K temperature for 1 week. The viscosity of the AG was found to be 214.7 cP at 2% dosage. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and average particle size determination revealed the filling of pores by AG gel solution, adsorption, and hydrogen bonding, which led to improvements in macroproperties. Full article
(This article belongs to the Special Issue Sustainable Polymeric Materials in Building and Construction)
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10 pages, 4399 KiB  
Article
Bubble-Free Frontal Polymerization of Acrylates via Redox-Initiated Free Radical Polymerization
by Morteza Ziaee and Mostafa Yourdkhani
Polymers 2024, 16(19), 2830; https://doi.org/10.3390/polym16192830 - 7 Oct 2024
Viewed by 774
Abstract
Thermal frontal polymerization (FP) of acrylate monomers mixed with conventional peroxide initiators leads to significant bubble formation at the polymerizing front, limiting their practical applications. Redox initiators present a promising alternative to peroxide initiators, as they prevent the formation of gaseous byproducts during [...] Read more.
Thermal frontal polymerization (FP) of acrylate monomers mixed with conventional peroxide initiators leads to significant bubble formation at the polymerizing front, limiting their practical applications. Redox initiators present a promising alternative to peroxide initiators, as they prevent the formation of gaseous byproducts during initiator decomposition and lower the front temperature, thereby enabling bubble-free FP. In this study, we investigate the FP of acrylate monomers of varying functionalities, including methyl methacrylate (MMA), 1,6-hexanediol diacrylate (HDDA), and trimethylolpropane triacrylate (TMPTA), using N,N-dimethylaniline/benzoyl peroxide (DMA/BPO) redox couple at room temperature and compare their front behavior, pot life, and bubble formation with those of same resin systems mixed with a conventional peroxide initiator, Luperox 231. The use of redox couples in FP of acrylates shows promise for rapid, energy-efficient manufacturing of polyacrylates and can enable new applications such as 3D printing and composite manufacturing. Full article
(This article belongs to the Special Issue Cross-Linked Polymers II)
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13 pages, 1720 KiB  
Article
Quantitative Study on Reinforcing Mechanism of Nanofiller Network in Silicone Elastomer Based on Fluorescence Labeling Technology
by Yuquan Li, Yuqi Xiong, Ming Kang, Fengmei Yu and Ai Lu
Polymers 2024, 16(19), 2829; https://doi.org/10.3390/polym16192829 - 7 Oct 2024
Viewed by 610
Abstract
Although there have been many theoretical studies on the enhancement effect of nanofiller networks and their interaction with elastomer molecular chains on the mechanical properties of elastomers, its mechanism description is still not completely clear. One of the main obstacles is the lack [...] Read more.
Although there have been many theoretical studies on the enhancement effect of nanofiller networks and their interaction with elastomer molecular chains on the mechanical properties of elastomers, its mechanism description is still not completely clear. One of the main obstacles is the lack of quantitative characterization techniques and corresponding theoretical models for the three-dimensional morphology of complex nanofiller networks. In this paper, the precipitated silica-filled silicone rubber was studied by fluorescence labeling combined with laser scanning confocal microscopy, and the real three-dimensional images of dispersion and aggregation structure of filled rubber systems were obtained. The microstructure evolution of nano-particle aggregates caused by the increase in the filler volume fraction was quantitatively described, and the reinforcement mechanism of elastomers with a distribution of aggregates and filler networks composed of nanoparticles was studied. Furthermore, a nano-composite reinforcement model based on volume fraction, particle shape, interaction, and filler dispersion has been proposed. Full article
(This article belongs to the Section Polymer Physics and Theory)
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22 pages, 10194 KiB  
Article
Synthesis and Performance Evaluation of Metallocene Polyalphaolefins (mPAO) Base Oil with Anti-Friction and Anti-Wear Properties
by Qidi Hu, Kai Zeng, Sheng Han, Jian Xu, Wenjing Hu and Jiusheng Li
Polymers 2024, 16(19), 2828; https://doi.org/10.3390/polym16192828 - 6 Oct 2024
Viewed by 634
Abstract
Anti-wear and anti-oxidation abilities are two key properties of lubricants that play a crucial role in ensuring long-term stable equipment operation. In this study, we aimed to develop a base oil with good anti-oxidation and anti-wear properties for use under extreme pressure. The [...] Read more.
Anti-wear and anti-oxidation abilities are two key properties of lubricants that play a crucial role in ensuring long-term stable equipment operation. In this study, we aimed to develop a base oil with good anti-oxidation and anti-wear properties for use under extreme pressure. The as-prepared metallocene polyalphaolefin (mPAO) was chemically modified using the trifluoromethanesulfonic acid (TfOH) catalysis through an alkylating reaction with triphenyl phosphorothioate (TPPT). During the experiments, when the reaction temperature exceeded 70 °C or the concentration of TfOH exceeded 2.67%, the β-scission reaction in the alkylation process became significantly more pronounced. The physical and chemical properties of TPPT-modified mPAO (T-mPAO) were evaluated by nuclear magnetic resonance spectroscopy, Fourier trans-form infrared spectroscopy, gel–permeation chromatography, and ASTM standards. T-mPAO showed significantly improved antioxidant capacity, with the initial oxidation temperature increasing by 32 °C compared to the base oil, and it exhibited the slowest increase in acid number in the 96-h oven oxidation test. The tribological tests showed that T-mPAO had the lowest friction coefficient, wear track, and wear rate (72.7% lower than that of mPAO) as well as the highest PB (238 kg) and PD (250 kg) among all tested samples. Compared to mPAO, the average friction coefficient of TPPT-modified mPAO in the four-ball friction test was reduced by 30.5%, and by 16.4% in the TE77 reciprocating friction test. Based on the experimental results, T-mPAO had strong anti-oxidation ability and excellent lubricating performance.The successful synthesis of multifunctional mPAO has enabled lubricant base oil additization, making it possible to use it in more demanding work scenarios, greatly broadening its application scope and making lubricant formulation blending more flexible. Full article
(This article belongs to the Section Polymer Chemistry)
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29 pages, 7118 KiB  
Review
3D Printing of Wood Composites: State of the Art and Opportunities
by Johan Ramaux, Isabelle Ziegler-Devin, Arnaud Besserer and Cécile Nouvel
Polymers 2024, 16(19), 2827; https://doi.org/10.3390/polym16192827 - 6 Oct 2024
Viewed by 846
Abstract
With the production of wood waste constantly on the increase, questions relating to its recycling and reuse are becoming unavoidable. The reuse of wood and its derivatives can be achieved through the production of composite materials, using wood as a reinforcement or even [...] Read more.
With the production of wood waste constantly on the increase, questions relating to its recycling and reuse are becoming unavoidable. The reuse of wood and its derivatives can be achieved through the production of composite materials, using wood as a reinforcement or even as the main matrix of the material. Additive manufacturing (also known as 3D printing) is an emerging and very promising process, particularly with the use of bio-based and renewable materials such as wood or its industrial derivatives. The aim of this paper is to present an overview of additive manufacturing processes using wood as a raw material and including industrial solutions. After presenting wood and its waste products, all the additive manufacturing processes using wood or its industrial derivatives will be presented. Finally, for each 3D printing process, this review will consider the current state of research, the industrial solutions that may exist, as well as the main challenges and issues that still need to be overcome. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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13 pages, 1531 KiB  
Article
Palladium-Functionalized Polysiloxane Drop-Casted on Carbon Paper as a Heterogeneous Catalyst for the Suzuki–Miyaura Reaction
by Ekaterina A. Golovenko, Anastasia N. Kocheva, Artem V. Semenov, Svetlana O. Baykova, Konstantin V. Deriabin, Sergey V. Baykov, Vadim P. Boyarskiy and Regina M. Islamova
Polymers 2024, 16(19), 2826; https://doi.org/10.3390/polym16192826 - 6 Oct 2024
Viewed by 513
Abstract
In this work, a Pd(II)-C,N-cyclometalated complex was grafted to polysiloxanes via azide–alkyne cycloaddition. The obtained polymer–metal complex (Pd-PDMS) acts as a catalyst in the Suzuki–Miyaura reaction. Pd-PDMS was drop-casted onto a carbon fiber support, and the resulting membrane demonstrated catalytic activity [...] Read more.
In this work, a Pd(II)-C,N-cyclometalated complex was grafted to polysiloxanes via azide–alkyne cycloaddition. The obtained polymer–metal complex (Pd-PDMS) acts as a catalyst in the Suzuki–Miyaura reaction. Pd-PDMS was drop-casted onto a carbon fiber support, and the resulting membrane demonstrated catalytic activity in the cross-coupling reaction without yield loss after several catalytic cycles. The catalytic membrane allows for easy catalyst recycling and provides ultra-low palladium levels in Suzuki–Miyaura reaction products. Full article
(This article belongs to the Special Issue Polymer-Based Materials for Catalysis and Flexible Electronics)
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14 pages, 2161 KiB  
Article
Comparison of Biowaste Fillers Extracted from Fish Scales and Collagen on the Mechanical Properties of High-Density Polyurethane Foams
by Zodidi Obiechefu, Stanley Chibuzor Onwubu, Deneshree Naidoo, Thabang Hendrica Mokhothu and Phumlane Selby Mdluli
Polymers 2024, 16(19), 2825; https://doi.org/10.3390/polym16192825 - 6 Oct 2024
Viewed by 755
Abstract
The utilization of biowaste fillers in the development of high-density polyurethane (PU) foams has gained significant attention due to environmental and economic benefits. This study investigates the mechanical properties of PU foams reinforced with biowaste fillers extracted from fish scales (FS) and fish [...] Read more.
The utilization of biowaste fillers in the development of high-density polyurethane (PU) foams has gained significant attention due to environmental and economic benefits. This study investigates the mechanical properties of PU foams reinforced with biowaste fillers extracted from fish scales (FS) and fish scale-derived collagen (FSC). The fish scales and collagen were characterized for their composition and integrated into PU foams at various loadings. Mechanical properties such as tensile strength, hardness, and density were evaluated. ANOVA was used to analyze the mean values. Bonferroni tests were used to identify differences between the filler materials (α = 0.05). The tensile strength increases with an increase in filler content for both FS (59.48 Kpa) and FSC (65.43 Kpa). No differences were observed between FS and FSC in tensile strength. Significant differences were observed between the FS and FSC in both hardness and density (p < 0.001). The results demonstrated that both fillers enhanced the mechanical properties of PU foams, with collagen-reinforced foams showing superior performance. This suggests that collagen and fish scales can be effective biowaste fillers for developing environmentally friendly PU foams with enhanced mechanical properties. Full article
(This article belongs to the Collection Polyurethanes)
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14 pages, 4952 KiB  
Article
A Three-Dimensional Modeling Approach for Carbon Nanotubes Filled Polymers Utilizing the Modified Nearest Neighbor Algorithm
by Junpu Wang, Xiaozhuang Yue, Yuxuan Wang, Liupeng Di, Wenzhi Wang, Jingchao Wei and Fei Yu
Polymers 2024, 16(19), 2824; https://doi.org/10.3390/polym16192824 - 6 Oct 2024
Viewed by 543
Abstract
Carbon nanotubes (CNTs) are extensively utilized in the fabrication of high-performance composites due to their exceptional mechanical, electrical, and thermal characteristics. To investigate the mechanical properties of CNTs filled polymers accurately and effectively, a 3D modeling approach that incorporates the microstructural attributes of [...] Read more.
Carbon nanotubes (CNTs) are extensively utilized in the fabrication of high-performance composites due to their exceptional mechanical, electrical, and thermal characteristics. To investigate the mechanical properties of CNTs filled polymers accurately and effectively, a 3D modeling approach that incorporates the microstructural attributes of CNTs was introduced. Initially, a representative volume element model was constructed utilizing the modified nearest neighbor algorithm. During the modeling phase, a corresponding interference judgment method was suggested, taking into account the potential positional relationships among the CNTs. Subsequently, stress–strain curves of the model under various loading conditions were derived through finite element analysis employing the volume averaging technique. To validate the efficacy of the modeling approach, the stress within a CNT/epoxy resin composite with varying volume fractions under different axial strains was computed. The resulting stress–strain curves were in good agreement with experimental data from the existing literature. Hence, the modeling method proposed in this study provides a more precise representation of the random distribution of CNTs in the matrix. Furthermore, it is applicable to a broader range of aspect ratios, thereby enabling the CNT simulation model to more closely align with real-world models. Full article
(This article belongs to the Special Issue Polymer Nanoparticles: Synthesis and Applications—2nd Edition)
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17 pages, 16217 KiB  
Article
Investigation of Temperature at Al/Glass Fiber-Reinforced Polymer Interfaces When Drilling Composites of Different Stacking Arrangements
by Brahim Salem, Ali Mkaddem, Malek Habak, Yousef Dobah, Makram Elfarhani and Abdessalem Jarraya
Polymers 2024, 16(19), 2823; https://doi.org/10.3390/polym16192823 - 6 Oct 2024
Viewed by 535
Abstract
This attempt covers an investigation of cutting temperature at interfaces of Fiber Metal Laminates (FMLs) made of glass fiber-reinforced polymer (GFRP) stacked with an Al2020 alloy. GFRP/Al/GFRP and Al/GFRP/Al composite stacks are both investigated to highlight the effect of stacking arrangement on thermal [...] Read more.
This attempt covers an investigation of cutting temperature at interfaces of Fiber Metal Laminates (FMLs) made of glass fiber-reinforced polymer (GFRP) stacked with an Al2020 alloy. GFRP/Al/GFRP and Al/GFRP/Al composite stacks are both investigated to highlight the effect of stacking arrangement on thermal behavior within the interfaces. In a first test series, temperature history is recorded within the metal/composite stack interfaces using preinstalled thermocouples. In a second test series, a wireless telemetry system connected to K-type thermocouples implanted adjacent to the cutting edge of the solid carbide drill is used to record temperature evolution at the tool tip. Focus is put on the effects of cutting speed and stacking arrangement on the thrust force, drilling temperature, and delamination. From findings, the temperature histories show high sensitivity to the cutting speed. When cutting Al/GFRP/Al, the peak temperature is found to be much higher than that recorded in GFRP/Al/GFRP and exceeds the glass transition point of the GFRP matrix under critical cutting speeds. However, thrust force obtained at constitutive phases exhibits close magnitude when the stacking arrangement varies, regardless of cutting speed. Damage analysis is also discussed through the delamination factor at different stages of FML thickness. Full article
(This article belongs to the Special Issue Functional Polymer Composites: Synthesis, Characterization and Application II)
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13 pages, 2338 KiB  
Article
Using the Herschel–Bulkley Consistency Index to Characterise Complex Biopolymer Systems—The Effect of Screening
by Anand Raja, Philipp K. Wilfert and Stephen J. Picken
Polymers 2024, 16(19), 2822; https://doi.org/10.3390/polym16192822 - 6 Oct 2024
Viewed by 563
Abstract
The use of the consistency index, as determined from fitting rheological data to the Herschel–Bulkley model, is described such that it may yield systematic trends that allow a very convenient description of the dissipative flow properties of linear and branched (bio)polymers in general, [...] Read more.
The use of the consistency index, as determined from fitting rheological data to the Herschel–Bulkley model, is described such that it may yield systematic trends that allow a very convenient description of the dissipative flow properties of linear and branched (bio)polymers in general, both in molecular and weakly associated supramolecular solutions. The effects of charge-mediated interactions by the systematic variation of the ionic strength and hydrogen bonding by a systematic variation in pH, using levels that are frequently encountered in systems used in practice, is investigated. These effects are then captured using the associated changes in the intrinsic viscosity to highlight the above-mentioned trends, while it also acts as an internal standard to describe the data in a concise form. The trends are successfully captured up to 100 times the polymer coil overlap and 100,000 times the solvent viscosity (or consistency index). These results therefore enable the rapid characterization of biopolymer systems of which the morphology remains unknown and may continue to remain unknown due to the wide-ranging monomer diversity and a lack of regularity in the structure, while the macromolecular coil size may be determined readily. Full article
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5 pages, 187 KiB  
Editorial
Mechanical Behavior of Polymeric Materials: Recent Studies
by Emilia P. Collar and Jesús-María García-Martínez
Polymers 2024, 16(19), 2821; https://doi.org/10.3390/polym16192821 - 5 Oct 2024
Viewed by 419
Abstract
This Special Issue is devoted to one of the most exciting fields in polymer science and technology: the many factors that influence the properties of polymer-based materials [...] Full article
(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Study)
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