Polymers

20 pages, 3049 KiB

Open AccessArticle

Coassembly of a Hybrid Synthetic–Biological Chitosan-g-Poly(N-isopropylacrylamide) Copolymer with DNAs of Different Lengths

by Maria Karayianni, Elena-Daniela Lotos, Marcela Mihai and Stergios Pispas

Polymers 2024, 16(21), 3101; https://doi.org/10.3390/polym16213101 - 4 Nov 2024

Viewed by 671

Abstract

Natural polysaccharides can serve as carriers of genes owing to their intrinsic biocompatibility, biodegradability, and low toxicity. Additionally, they can be easily chemically modified, e.g., through grafting, leading to hybrid synthetic–biological copolymers with additional functionalities. In this work we report on the electrostatic [...] Read more.

Natural polysaccharides can serve as carriers of genes owing to their intrinsic biocompatibility, biodegradability, and low toxicity. Additionally, they can be easily chemically modified, e.g., through grafting, leading to hybrid synthetic–biological copolymers with additional functionalities. In this work we report on the electrostatic interaction between a chitosan-g-poly(N-isopropylacrylamide) (Chit-g-PNIPAM) copolymer and DNA macromolecules of different lengths (i.e., 50 and 2000 bp), towards the construction of polyplexes that can serve as potential gene delivery systems. At the basic science level, the work aims to elucidate the effects of DNA length on the structural and physicochemical properties of the thermoresponsive hybrid macromolecular assemblies. The protonated amino groups on the chitosan backbone enable electrostatic binding with the anionic phosphate groups of the DNA molecules, while the PNIPAM side chains are expected to impart thermoresponsive properties to the formed polyplexes. Different amino to phosphate group (N/P) mixing ratios were examined, aiming to produce stable dispersions. The physicochemical properties of the resulting polyplexes were investigated by dynamic and electrophoretic light scattering (DLS and ELS), while their morphology was studied by scanning-transmission electron microscopy (STEM). Moreover, their response to changes in temperature and ionic strength, as well as their stability against biological media, was also examined. Finally, the binding affinity of the copolymer towards DNA was evaluated through fluorescence spectroscopy, using ethidium bromide quenching assays, while infrared spectroscopy was used to investigate the structure of the incorporated DNA chains. Full article

(This article belongs to the Special Issue Recent Developments in Biodegradable and Biobased Polymers II)

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21 pages, 5599 KiB

Open AccessArticle

Polypiperazine-Based Micelles of Mixed Composition for Gene Delivery

by Rumena Stancheva, Emi Haladjova, Maria Petrova, Iva Ugrinova, Ivaylo Dimitrov and Stanislav Rangelov

Polymers 2024, 16(21), 3100; https://doi.org/10.3390/polym16213100 - 4 Nov 2024

Viewed by 725

Abstract

We introduce a novel concept in nucleic acid delivery based on the use of mixed polymeric micelles (MPMs) as platforms for the preparation of micelleplexes with DNA. MPMs were prepared by the co-assembly of a cationic copolymer, poly(1-(4-methylpiperazin-1-yl)-propenone)-b-poly(d,l-lactide), and [...] Read more.

We introduce a novel concept in nucleic acid delivery based on the use of mixed polymeric micelles (MPMs) as platforms for the preparation of micelleplexes with DNA. MPMs were prepared by the co-assembly of a cationic copolymer, poly(1-(4-methylpiperazin-1-yl)-propenone)-b-poly(d,l-lactide), and nonionic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) block copolymers. We hypothesize that by introducing nonionic entities incorporated into the mixed co-assembled structures, the mode and strength of DNA binding and DNA accessibility and release could be modulated. The systems were characterized in terms of size, surface potential, buffering capacity, and binding ability to investigate the influence of composition, in particular, the poly(ethylene oxide) chain length on the properties and structure of the MPMs. Endo–lysosomal conditions were simulated to follow the changes in fundamental parameters and behavior of the micelleplexes. The results were interpreted as reflecting the specific structure and composition of the corona and localization of DNA in the corona, predetermined by the poly(ethylene oxide) chain length. A favorable effect of the introduction of the nonionic block copolymer component in the MPMs and micelleplexes thereof was the enhancement of biocompatibility. The slight reduction of the transfection efficiency of the MPM-based micelleplexes compared to that of the single-component polymer micelles was attributed to the premature release of DNA from the MPM-based micelleplexes in the endo–lysosomal compartments. Full article

(This article belongs to the Topic Applications of Polymers and Polymer Nanomaterials in Drug Delivery and Nanomedicine)

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2 pages, 6922 KiB

Open AccessCorrection

Correction: El-Hefnawy et al. Fabrication of Nanofibers Based on Hydroxypropyl Starch/Polyurethane Loaded with the Biosynthesized Silver Nanoparticles for the Treatment of Pathogenic Microbes in Wounds. Polymers 2022, 14, 318

by Mohamed E. El-Hefnawy, Sultan Alhayyani, Mohsen M. El-Sherbiny, Mohamed I. Sakran and Mohamed H. El-Newehy

Polymers 2024, 16(21), 3099; https://doi.org/10.3390/polym16213099 - 4 Nov 2024

Viewed by 569

Abstract

There was an error in the original publication [...] Full article

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16 pages, 4654 KiB

Open AccessReview

A Comprehensive Review on the Incremental Sheet Forming of Polycarbonate

by Antonio Formisano and Massimo Durante

Polymers 2024, 16(21), 3098; https://doi.org/10.3390/polym16213098 - 3 Nov 2024

Viewed by 870

Abstract

Incremental sheet forming has emerged as an excellent alternative to other material forming procedures, incrementally deforming flat metal sheets into complex three-dimensional profiles. The main characteristics of this process are its versatility and cost-effectiveness; additionally, it allows for greater formability compared to conventional [...] Read more.

Incremental sheet forming has emerged as an excellent alternative to other material forming procedures, incrementally deforming flat metal sheets into complex three-dimensional profiles. The main characteristics of this process are its versatility and cost-effectiveness; additionally, it allows for greater formability compared to conventional sheet forming processes. Recently, its application has been extended to polymers and composites. The following review aims to present the current state of the art in the incremental sheet forming of polycarbonate, an outstanding engineering plastic, beginning with initial studies on the feasibility of this process for polymers. Attention is given to the advantages, drawbacks, and main applications of incrementally formed polycarbonate sheets, as well as the influence of process parameters and toolpath strategies on features such as formability, forming forces, deformation and failure mechanisms, geometric accuracy, surface quality, etc. Additionally, new hybrid forming methods for process optimisation are presented. Finally, a discussion is provided on the technical challenges and future research directions for incremental sheet forming of polycarbonate and, more generally, thermoplastics. Thus, this review aims to offer an extensive overview of the incremental forming of polycarbonate sheets, useful to both academic and industrial researchers working on this topic. Full article

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

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19 pages, 7025 KiB

Open AccessArticle

Energy Consumption Prediction of Injection Molding Process Based on Rolling Learning Informer Model

by Jianfeng Huang, Yi Li, Xinyuan Li, Yucheng Ding, Fenglian Hong and Shitong Peng

Polymers 2024, 16(21), 3097; https://doi.org/10.3390/polym16213097 - 2 Nov 2024

Viewed by 800

Abstract

Accurate energy consumption prediction in the injection molding process is crucial for optimizing energy efficiency in polymer processing. Traditional parameter optimization methods face challenges in achieving optimal energy prediction due to complex energy transmission. In this study, a data-driven approach based on the [...] Read more.

Accurate energy consumption prediction in the injection molding process is crucial for optimizing energy efficiency in polymer processing. Traditional parameter optimization methods face challenges in achieving optimal energy prediction due to complex energy transmission. In this study, a data-driven approach based on the Rolling Learning Informer model is proposed to enhance the accuracy and adaptability of energy consumption forecasting. The Informer model addresses the limitations of long-sequence prediction with sparse attention mechanisms, self-attention distillation, and generative decoder techniques. Rolling learning prediction is incorporated to enable continuous updating of the model to reflect new data trends. Experimental results demonstrate that the RL-Informer model achieves a normalized root mean square error of 0.1301, a root mean square error of 0.0758, a mean absolute error of 0.0562, and a coefficient of determination of 0.9831 in energy consumption forecasting, outperforming other counterpart models like Gated Recurrent Unit, Temporal Convolutional Networks, Long Short-Term Memory, and two variants of the pure Informer models without Rolling Learning. It is of great potential for practical engineering applications. Full article

(This article belongs to the Special Issue Machine Learning and Artificial Intelligence for Polymer Injection Molding Design and Processing)

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21 pages, 17491 KiB

Open AccessArticle

Effect of Fiber Cross-Sectional and Surface Properties on the Degradation of Biobased Polymers

by Simon Schick, Andreas Weinberger, Robert Groten and Gunnar H. Seide

Polymers 2024, 16(21), 3096; https://doi.org/10.3390/polym16213096 - 2 Nov 2024

Viewed by 740

Abstract

Biobased polymers such as polylactic acid (PLA) and polybutylene succinate (PBS) break down naturally under certain environmental conditions. The efficiency of degradation can be linked directly to fiber surface properties, which influence polymer accessibility. Here, the degradation of PLA and PBS fibers with [...] Read more.

Biobased polymers such as polylactic acid (PLA) and polybutylene succinate (PBS) break down naturally under certain environmental conditions. The efficiency of degradation can be linked directly to fiber surface properties, which influence polymer accessibility. Here, the degradation of PLA and PBS fibers with six different cross-sections was investigated. The fibers were aged by hydrolysis and UV exposure in an accelerated weathering test, followed by an ISO 20200 laboratory-scale disintegration test with non-aged fibers as controls. The polymers were analyzed by differential scanning calorimetry, Fourier transform infrared spectroscopy, and gel permeation chromatography, comparing the polymer granulate, virgin fibers, and UV-exposed fibers. It was found that the molecular mass and crystallinity of PBS changed more than PLA during spinning. Several PLA samples were completely degraded, whereas all the PBS samples remained intact. Furthermore, surface openings appeared on the PLA fibers during weathering, suggesting greater sensitivity to UV exposure and hydrolysis than PBS. A clear correlation between the fiber surface area and the degradation rate was observed for all samples, but the correlation was positive for PLA and negative for PBS. The slower degradation of PBS fibers with a larger surface area may reflect the ability of PBS to preserve itself by further crystallization during degradation processes at temperatures higher than the glass transition point. The data clearly show that the analysis of single degradation mechanisms is insufficient to predict the behavior of material under real-world conditions, where different degradation mechanisms may work in parallel or consecutively, and may show interdependencies. Full article

(This article belongs to the Special Issue Biodegradable Polymers: Synthesis, Characterization and Applications)

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13 pages, 3849 KiB

Open AccessArticle

Dual-Template Molecularly Imprinted Polymers for Dispersive Solid-Phase Extraction Combined with High Performance Liquid Chromatography for the Determination of Sulfonamide Antibiotics in Environmental Water Samples

by Yuhao Wen, Mingyang Hou, Xingkai Hao, Dani Sun, Hao Zhang, Farooq Saqib, Wenhui Lu, Huitao Liu, Lingxin Chen and Jinhua Li

Polymers 2024, 16(21), 3095; https://doi.org/10.3390/polym16213095 - 1 Nov 2024

Viewed by 731

Abstract

In this study, we designed a molecularly imprinted polymers-dispersive solid-phase extraction-high-performance liquid chromatography (MIPs-DSPE-HPLC) method, as a simple and efficient platform for the sensitive detection of two sulfonamide antibiotics (SAs) of sulfamethoxine (SMM) and sulfamethoxazole (SMZ) in environmental water samples. Using SMM and [...] Read more.

In this study, we designed a molecularly imprinted polymers-dispersive solid-phase extraction-high-performance liquid chromatography (MIPs-DSPE-HPLC) method, as a simple and efficient platform for the sensitive detection of two sulfonamide antibiotics (SAs) of sulfamethoxine (SMM) and sulfamethoxazole (SMZ) in environmental water samples. Using SMM and SMZ as templates, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the crosslinking agent, and azodiisobutyronitrile as the catalyst, the dual-template molecularly imprinted polymers (dt-MIPs) were successfully synthesized via surface imprinting technology and multi-template imprinting strategy. The adsorption properties of the prepared MIPs were characterized, and the adsorption capacities of MIPs towards SMZ and SMM were 27.35 mg/g and 30.92 mg/g, respectively. The detection limits of the method in three environmental water samples were in the range of 0.23–1.74 μg/L, and the recoveries were between 82.7 and 110.3%, with relative standard deviations less than 5.93%. The construction process of this MIPs-DSPE-HPLC method is straightforward, exhibits high sensitivity and selectivity, and thus provides a versatile method for the quantification of SAs in complex matrices. Full article

(This article belongs to the Special Issue Advance in Molecularly Imprinted Polymers II)

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17 pages, 3950 KiB

Open AccessArticle

Formation of Superhydrophobic Coatings Based on Dispersion Compositions of Hexyl Methacrylate Copolymers with Glycidyl Methacrylate and Silica Nanoparticles

by Viktor V. Klimov, Alexey K. Shilin, Daniil A. Kusakovskiy, Olga V. Kolyaganova, Valentin O. Kharlamov, Alexander V. Rudnev, Manh D. Le, Evgeny V. Bryuzgin and Alexander V. Navrotskii

Polymers 2024, 16(21), 3094; https://doi.org/10.3390/polym16213094 - 1 Nov 2024

Viewed by 612

Abstract

In the last decade, the task of developing environmentally friendly and cost-effective methods for obtaining stable superhydrophobic coatings has become topical. In this study, we examined the effect of the concentrations of filler and polymer binder on the hydrophobic properties and surface roughness [...] Read more.

In the last decade, the task of developing environmentally friendly and cost-effective methods for obtaining stable superhydrophobic coatings has become topical. In this study, we examined the effect of the concentrations of filler and polymer binder on the hydrophobic properties and surface roughness of composite coatings made from organic–aqueous compositions based on hexyl methacrylate (HMA) and glycidyl methacrylate (GMA) copolymers. Silicon dioxide nanoparticles were used as a filler. A single-stage “all-in-one” aerosol application method was used to form the coatings without additional intermediate steps for attaching the adhesive layer or texturing the substrate surface, as well as pre-modification of the surface of filler nanoparticles. As the ratio of the mass fraction of polymer binder (Wn) to filler (Wp) increases, the coatings show the lowest roll-off angles among the whole range of samples studied. Coatings with an optimal mass fraction ratio (Wn/Wp = 1.2 ÷ 1.6) of the filler to polymer binder maintained superhydrophobic properties for 24 h in contact with a drop of water in a chamber saturated with water vapor and exhibited roll-off angles of 6.1° ± 1°. Full article

(This article belongs to the Special Issue Advanced Polymer Coating Technology)

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20 pages, 13685 KiB

Open AccessArticle

Impact of Bond–Slip Models on Debonding Behavior in Strengthened RC Slabs Using Recycled Waste Fishing Net Sheets

by Huy Q. Nguyen, Taek Hee Han, Jun Kil Park and Jung J. Kim

Polymers 2024, 16(21), 3093; https://doi.org/10.3390/polym16213093 - 1 Nov 2024

Viewed by 673

Abstract

This study investigated the performance of recycled waste fishing net sheets (WSs) as a sustainable strengthening material for reinforced concrete (RC) slabs. The primary challenge addressed is the debonding failure caused by the low bond strength at the WS-to-concrete interface. To analyze this, [...] Read more.

This study investigated the performance of recycled waste fishing net sheets (WSs) as a sustainable strengthening material for reinforced concrete (RC) slabs. The primary challenge addressed is the debonding failure caused by the low bond strength at the WS-to-concrete interface. To analyze this, two full-scale RC slabs—one with and one without strengthening—were cast and tested under a four-point bending setup. Finite element (FE) models incorporating existing bond–slip laws were developed using the ABAQUS software to simulate the strengthened slab’s behavior. A sensitivity analysis was performed to assess the impact of bond–slip parameters on the failure mechanism. Experimental results indicated that the WS-strengthened slab enhanced the RC slab capacities by 15% in yield load and 13% in initial stiffness. Furthermore, the maximum shear stress of 0.5τ_max or interfacial fracture energy of 0.2G_f, compared to values proposed by Monti et al., enabled the simulation of the global response observed in the experiment. Full article

(This article belongs to the Special Issue Simulation and Calculation of Polymer Composite Materials)

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20 pages, 8018 KiB

Open AccessArticle

Extrusion Parameters Optimization and Mechanical Properties of Bio-Polyamide 11-Based Biocomposites Reinforced with Short Basalt Fibers

by Vito Gigante, Francesca Cartoni, Bianca Dal Pont and Laura Aliotta

Polymers 2024, 16(21), 3092; https://doi.org/10.3390/polym16213092 - 31 Oct 2024

Viewed by 688

Abstract

The increasing demand for sustainable materials in high-value applications, particularly in the automotive industry, has prompted the development of biocomposites based on renewable or recyclable matrices and natural fibers as reinforcements. In this context, this paper aimed to produce composites with improved mechanical [...] Read more.

The increasing demand for sustainable materials in high-value applications, particularly in the automotive industry, has prompted the development of biocomposites based on renewable or recyclable matrices and natural fibers as reinforcements. In this context, this paper aimed to produce composites with improved mechanical and thermal properties (tensile, flexural, and heat deflection temperature) through an optimized process pathway using a biobased polyamide reinforced with short basalt fibers. This study emphasizes the critical impact of fiber length, matrix adhesion, and the variation in matrix properties with increasing fiber content. These factors influence the properties of short-fiber composites produced via primary processing using extrusion and shaped through injection molding. The aim of this work was to optimize extrusion conditions using a 1D simulation software to minimize excessive fiber fragmentation during the extrusion process. The predictive model’s capacity to forecast fiber degradation and the extent of additional fiber breakage during extrusion was evaluated. Furthermore, the impact of injection molding on these conditions was investigated. Moreover, a comprehensive thermomechanical characterization of the composites, comprising 10%, 20%, and 30% fiber content, was carried out, focusing on the correlation with morphology and processing using SEM and micro-CT analyses. In particular, how the extrusion process parameters adopted can influence fiber breakage and how injection molding can influence the fiber orientation were investigated, highlighting their influence in determining the final mechanical properties of short fiber composites. By optimizing the process parameters, an increment with respect to bio-PA11 in the tensile strength of 38%, stiffness of 140%, and HDT of 77% compared to the matrix were obtained. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Polymer Blends and Composites)

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14 pages, 2714 KiB

Open AccessArticle

Rheological Behavior of Clay Tailings in the Presence of Divalent Cations and Sodium Polyacrylate: Insights from Molecular Dynamics Simulations

by Jahir J. Ramos, Steven Nieto, Gonzalo R. Quezada, Williams Leiva, Pedro Robles, Fernando Betancourt and Ricardo I. Jeldres

Polymers 2024, 16(21), 3091; https://doi.org/10.3390/polym16213091 - 31 Oct 2024

Viewed by 614

Abstract

This study analyzes the behavior of sodium polyacrylate (NaPA) as a rheological modifier for clay-based tailings. Special emphasis is placed on the impact of calcium and magnesium ions in industrial water, which are analyzed through rheograms, zeta potential measurements, and molecular dynamics simulations. [...] Read more.

This study analyzes the behavior of sodium polyacrylate (NaPA) as a rheological modifier for clay-based tailings. Special emphasis is placed on the impact of calcium and magnesium ions in industrial water, which are analyzed through rheograms, zeta potential measurements, and molecular dynamics simulations. The results are interpreted as electrostatic interactions, steric phenomena, and cation solvation. This interpretation integrates experimental studies with microscopic analyses, employing molecular dynamics simulations to elucidate the underlying mechanisms. In all cases, a decrease in the yield stress of synthetic slurries is observed as the dosing of NaPA increases due to greater repulsion between tailings particles through an increase in electrostatic repulsion and larger steric forces that hinder agglomeration. However, efficiency is reduced in the presence of divalent cations as zeta potential measurements suggest a reduction in the electrical charges of the particles and the polymer, making its application more challenging. The differences obtained in the presence of calcium compared to magnesium are explained in terms of the solvation of these ions and their impact on the polymer conformation in solution and adsorption on the mineral surfaces. This explanation is reinforced by molecular dynamics studies, which indicate that polymer adsorption on minerals depends on the type of mineral and type of ion. Particularly for quartz, the highest adsorption of NaPA occurs in the presence of calcium, whereas for a kaolinite surface, the highest polymer adsorption is obtained in the presence of magnesium. The competitive effect of these phenomena leads to the rheological behavior of the tailings being dominated by the effects originating in the clay. Full article

(This article belongs to the Special Issue Status and Progress of Soluble Polymers II)

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17 pages, 4956 KiB

Open AccessArticle

Evaluation of the UV Protection Properties of Para-Aramid Woven Fabrics with Various Specialty Core Yarns

by Klara Kostajnšek, Matejka Bizjak, Gözde Ertekin and Mustafa Ertekin

Polymers 2024, 16(21), 3090; https://doi.org/10.3390/polym16213090 - 31 Oct 2024

Viewed by 533

Abstract

Para-aramid fibers, known for their remarkable strength and thermal stability, are frequently employed in protective textiles for military and aerospace applications. However, continuous exposure to ultraviolet (UV) radiation can damage their protective characteristics. This study analyzes the ultraviolet protection factor (UPF) and UV [...] Read more.

Para-aramid fibers, known for their remarkable strength and thermal stability, are frequently employed in protective textiles for military and aerospace applications. However, continuous exposure to ultraviolet (UV) radiation can damage their protective characteristics. This study analyzes the ultraviolet protection factor (UPF) and UV transmittance of woven fabrics produced from 30/2 Ne spun para-aramid yarns in the warp and 10 Ne core-spun yarns in the weft. The weft yarns consisted of three sheath fibers—para-aramid, meta-aramid, and polyester—in combination with different specialty core materials. The results show significant differences in UPF before and after UV exposure, with para-aramid sheaths giving the highest improvement. UV exposure caused structural changes in the fibers, resulting in increased UV protection, particularly in fabrics with para-aramid sheaths. This study concludes that the combination of para-aramid fibers with specific core materials significantly enhances UV protection, making them well-suited for applications in high UV exposure environments. Full article

(This article belongs to the Special Issue Advanced Study on Polymer-Based Textiles)

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15 pages, 4206 KiB

Open AccessArticle

Reinforcement of Epoxidized Natural Rubber with High Antimicrobial Resistance Using Water Hyacinth Fibers and Chlorhexidine Gluconate

by Thidarat Kanthiya, Pornchai Rachtanapun, Siwarote Boonrasri, Thorsak Kittikorn, Thanongsak Chaiyaso, Patnarin Worajittiphon, Nuttapol Tanadchangsaeng, Sarinthip Thanakkasaranee, Noppol Leksawasdi, Yuthana Phimolsiripol, Warintorn Ruksiriwanich and Kittisak Jantanasakulwong

Polymers 2024, 16(21), 3089; https://doi.org/10.3390/polym16213089 - 31 Oct 2024

Viewed by 628

Abstract

In this study, epoxidized natural rubber (ENR) was mixed using a two-roller mixer. Water hyacinth fiber (WHF) acted as a reinforcing agent in the preparation of the rubber composite at 10 phr (ENRC/WHF). Chlorhexidine gluconate (CHG) was added at different concentrations (1, 5, [...] Read more.

In this study, epoxidized natural rubber (ENR) was mixed using a two-roller mixer. Water hyacinth fiber (WHF) acted as a reinforcing agent in the preparation of the rubber composite at 10 phr (ENRC/WHF). Chlorhexidine gluconate (CHG) was added at different concentrations (1, 5, 10, and 20 phr) as an antimicrobial and coupling agent. The tensile strength increased with a CHG content of 1 phr (4.59 MPa). The ENRC/WHF/CHG20 blend offered high hardness (38) and good morphology owing to the reduction in cavities and fiber pull-out from the rubber matrix. The swelling of the sample blends in oil and toluene decreased as the CHG content increased. Reactions of –NH₂/epoxy groups and –NH₂/–OH groups occurred during the preparation of the ENRC/WHF/CHG blend. The FTIR spectroscopy peak at 1730 cm⁻¹ confirmed the reaction between the −NH₂ groups of CHG and epoxy groups of ENR. The ENRC/WHF/CHG blend at 10 phr and 20 phr exhibited zones of inhibition against three bacterial species (Staphylococcus aureus, Escherichia coli, and Bacillus cereus). CHG simultaneously acted as a crosslinking agent between ENR and WHF and as an antimicrobial additive for the blends. CHG also improved the tensile strength, hardness, swelling, and antimicrobial properties of ENR composites. Full article

(This article belongs to the Special Issue Mechanical and Structural Behavior for Polymer Composites)

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26 pages, 5115 KiB

Open AccessArticle

Chemical and Rheological Evaluation of the Ageing Behaviour of High-Content Crumb Rubber Asphalt Binder

by Zhilian Ji, Zhibin Wang, Lei Feng, Peikai He and Song Li

Polymers 2024, 16(21), 3088; https://doi.org/10.3390/polym16213088 - 31 Oct 2024

Viewed by 506

Abstract

High-Content Crumb Rubber Asphalt (HCRA) binder improves road performance and address waste tyre pollution, yet its ageing behaviour is not fully understood. In this study, 70# neat asphalt binder and HCRA with rubber contents of 35% and 50% were selected and aged through [...] Read more.

High-Content Crumb Rubber Asphalt (HCRA) binder improves road performance and address waste tyre pollution, yet its ageing behaviour is not fully understood. In this study, 70# neat asphalt binder and HCRA with rubber contents of 35% and 50% were selected and aged through the Thin Film Oven Test (TFOT) and Pressure Ageing Vessel (PAV) tests. FTIR (Fourier Transform Infrared Spectroscopy) and DSR (Dynamic Shear Rheometer) were employed to investigate their chemical composition and rheological properties. The FTIR results show that HCRA’s chemical test results are similar to those of 70#, but HCRA is more susceptible to ageing. I(C=C) strength decreases with age. The DSR results show that HCRA outperforms 70# neat asphalt binder in terms of viscoelasticity, high temperature performance and fatigue resistance, and exhibits greater resistance to ageing. The ageing index (AI) was obtained through a calculation using the formula, and overall, 70# neat asphalt binder is more sensitive to ageing behaviour and less resistant to ageing, and HCRA is particularly outstanding for fatigue resistance. A strong correlation is observed between chemical composition and some rheological property indicators. Therefore, we are able to predict the rheological properties using chemical composition indicators. This study provides insight into the ageing behaviour of a neat asphalt binder and an HCRA binder and demonstrates that the HCRA binder outperforms conventional asphalt in several performance areas. It also provides theoretical support for the consumption of waste tyres to prepare high content crumb rubber asphalt. Full article

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

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17 pages, 4482 KiB

Open AccessArticle

Dual Loading of Trans-Cinnamaldehyde and Either Paclitaxel or Curcumin in Chitosan Nanoparticles: Physicochemical Characterization and Biological Evaluation Against MDCK and HeLa Cells

by Cynthia L. Barrera-Martínez, Héctor I. Meléndez-Ortiz, Felipe Padilla-Vaca, Leonard I. Atanase, René D. Peralta-Rodríguez and Ioannis Liakos

Polymers 2024, 16(21), 3087; https://doi.org/10.3390/polym16213087 - 31 Oct 2024

Viewed by 642

Abstract

Biopolymer chitosan sub-micron particles (CSMPs) were prepared by the ionic gelation technique crosslinked with sodium tripolyphosphate co-loaded with trans-cinnamaldehyde (TCIN), and either curcumin (CUR) or paclitaxel (PTX). The size of the spherical CSMPs increased from 118 nm to 136 nm and 170 nm [...] Read more.

Biopolymer chitosan sub-micron particles (CSMPs) were prepared by the ionic gelation technique crosslinked with sodium tripolyphosphate co-loaded with trans-cinnamaldehyde (TCIN), and either curcumin (CUR) or paclitaxel (PTX). The size of the spherical CSMPs increased from 118 nm to 136 nm and 170 nm after the loading of TCIN and CUR, whereas the loading of PTX led to a slight decrease (114 nm). Polydispersity indexes of all the samples were smaller than 0.4, indicating monodisperse particles. Zeta potential values higher than +40 mV were determined, which is direct proof of the high stability of these nanoparticles. TCIN and PTX release studies in vitro, at pH 6.5 and 7.4, showed a pH dependence on the release rate with a higher value at pH 6.5. However, CUR was not released from CSMPs probably due to strong interactions with CS biopolymer chains. Cytotoxicity studies showed that the systems loaded with TCIN and PTX were more cytotoxic for HeLa cancer cells than for MDCK cells. Moreover, a synergistic effect against HeLa cells was observed for the TCIN-PTX-loaded CSMP samples. The Sensitivity Index indicated that the CSMPs loaded with TCIN have a prospective attraction to carry and release conventional or new chemotherapeutic drugs. This study demonstrates the in vitro efficiency of the obtained drug delivery system, but in vivo studies are necessary to confirm its potential for clinical applications. Full article

(This article belongs to the Section Polymer Networks)

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20 pages, 5016 KiB

Open AccessArticle

Radiopaque Polyurethanes Containing Barium Sulfate: A Survey on Thermal, Rheological, Physical, and Structural Properties

by Heitor Luiz Ornaghi Júnior, Benoit Duchemin, Sanae Azzaye, Márcio Ronaldo Farias Soares, Bárbara Schneider and Carlos Henrique Romoaldo

Polymers 2024, 16(21), 3086; https://doi.org/10.3390/polym16213086 - 31 Oct 2024

Viewed by 495

Abstract

Radiopaque polyurethanes are extensively used in biomedical fields owing to their favorable balance of properties. This research aims to investigate the influence of particle concentration on various properties, including rheological, radiopacity, structural, thermal, and mechanical attributes, with a thorough analysis. The findings are [...] Read more.

Radiopaque polyurethanes are extensively used in biomedical fields owing to their favorable balance of properties. This research aims to investigate the influence of particle concentration on various properties, including rheological, radiopacity, structural, thermal, and mechanical attributes, with a thorough analysis. The findings are benchmarked against a commercial product (PL 8500 A) that contains 10% weight barium sulfate. Two more thermoplastic polyurethanes (TPU) were formulated with two different concentrations of barium sulfate (10 wt.% and 20 wt.%) and compared to the commercially available product. FTIR demonstrated similar absorption bands among all samples, indicating that the fabrication method did not impact the TPU matrix. DSC indicated a predominantly amorphous structure for PL 8500 A compared to the other samples, while the kinetic degradation was more influenced by the higher barium sulfate content. The rheological analysis showed a decrease in the complex viscosity and storage modulus with the radiopacifier and an increase in the radiopacity, as demonstrated by the X-radiography. X-ray microtomography showed a more spherical particle format with a heterogeneous particle structure for PL 8500 A compared to the other polyurethanes. These findings enhance the comprehension of the structure–property relationships inherent in these materials and facilitate the development of customized materials for targeted applications. Full article

(This article belongs to the Special Issue Advancements in Mechanical Properties and Material Testing in Polymer Science)

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10 pages, 1898 KiB

Open AccessArticle

Surface Wetting Behaviors of Hydroxyl-Terminated Polybutadiene: Molecular Mechanism and Modulation

by Xinke Zhang, Zhikun Liu, Bing Yuan and Kai Yang

Polymers 2024, 16(21), 3085; https://doi.org/10.3390/polym16213085 - 31 Oct 2024

Viewed by 408

Abstract

The surface wetting or coating of materials by polymers is crucial for designing functional interfaces and various industrial applications. However, the underlying mechanisms remain elusive. In this study, the wetting behavior of hydroxyl-terminated polybutadiene (HTPB) on a quartz surface was systematically investigated using [...] Read more.

The surface wetting or coating of materials by polymers is crucial for designing functional interfaces and various industrial applications. However, the underlying mechanisms remain elusive. In this study, the wetting behavior of hydroxyl-terminated polybutadiene (HTPB) on a quartz surface was systematically investigated using computer simulation methods. A notable tip-dominant surface adsorption mode of HTPB was identified, where the hydroxyl group at the end of the polymer chain binds to the surface to initiate the wetting process. Moreover, it was found that with the increase in the degree of polymerization (e.g., from DP = 10 to 30), spontaneous adsorption of HTPB becomes increasingly difficult, with a three-fold increase in the adsorption time. These results suggest a competition mechanism between enthalpy (e.g., adhesion between the polymer and the surface) and entropy (e.g., conformational changes in polymer chains) that underlies the wetting behavior of HTPB. Based on this mechanism, two strategies were employed: altering the degree of polymerization of HTPB and/or regulating the amount of interfacial water molecules (e.g., above or below the threshold amount of 350 on a 10 × 10 nm² surface). These strategies effectively modulate HTPB’s surface wetting process. This study provides valuable insights into the mechanisms underlying the surface adsorption behavior of HTPB and offers guidance for manipulating polymer wetting processes at interfaces. Full article

(This article belongs to the Special Issue Sustainable Polymers: Synthesis and Applications)

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20 pages, 6423 KiB

Open AccessArticle

Polyindole-Functionalized RGO-NiFe₂O₄-SiO₂ Nanocomposite: A Dual-Functional Nanomaterial for Efficient Antimony Adsorption and Subsequent Application in Supercapacitor

by Mohd Shoeb, Fouzia Mashkoor, Mohmmad Naved Khan and Changyoon Jeong

Polymers 2024, 16(21), 3084; https://doi.org/10.3390/polym16213084 - 31 Oct 2024

Viewed by 559

Abstract

Effective wastewater treatment remains a critical challenge, especially when dealing with hazardous pollutants like antimony (Sb(III)). This study addresses this issue by using innovative nanocomposites to remove Sb(III) ions from water, while simultaneously repurposing the spent adsorbents for energy storage applications. We developed [...] Read more.

Effective wastewater treatment remains a critical challenge, especially when dealing with hazardous pollutants like antimony (Sb(III)). This study addresses this issue by using innovative nanocomposites to remove Sb(III) ions from water, while simultaneously repurposing the spent adsorbents for energy storage applications. We developed reduced graphene oxide-NiFe₂O₃-SiO₂-polyindole nanocomposites (RGO-NiFe₂O₃-SiO₂-PIn NCs) via a hydrothermal synthesis method, achieving a high removal efficiency of 91.84% for Sb(III) ions at an initial concentration of 50 mg/L at pH 8. After adsorption, the exhausted adsorbent was repurposed for energy storage, effectively minimizing secondary pollution. The Sb(III)-loaded adsorbent (RGO-NiFe₂O₃-SiO₂-PIn@SbO_x) exhibited excellent performance as an energy storage material, with a specific capacitance (C_s) of 701.36 F/g at a current density of 2 A/g and a retention rate of 80.15% after 10,000 cycles. This dual-purpose approach not only advances wastewater treatment technologies but also contributes to sustainable and economical recycling practices, particularly in the field of energy storage. Full article

(This article belongs to the Special Issue Advanced Polymeric Materials for Wastewater Treatment)

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17 pages, 13842 KiB

Open AccessArticle

Fabrication of Functionalized Graphene Oxide–Aluminum Hypophosphite Nanohybrids for Enhanced Fire Safety Performance in Polystyrene

by Zhenzhen Deng, Tao Tang, Junjie Huo, Hui He and Kang Dai

Polymers 2024, 16(21), 3083; https://doi.org/10.3390/polym16213083 - 31 Oct 2024

Viewed by 436

Abstract

To enhance the fire safety performance in polystyrene (PS), a novel organic–inorganic hybrid material (FGO–AHP) was successfully prepared by the combination of functionalized graphene oxide (FGO) and aluminum hypophosphite (AHP) via a chemical deposition method. The resulting FGO–AHP nanohybrids were incorporated into PS [...] Read more.

To enhance the fire safety performance in polystyrene (PS), a novel organic–inorganic hybrid material (FGO–AHP) was successfully prepared by the combination of functionalized graphene oxide (FGO) and aluminum hypophosphite (AHP) via a chemical deposition method. The resulting FGO–AHP nanohybrids were incorporated into PS via a masterbatch-melt blending to produce PS/FGO–AHP nanocomposites. Scanning electron microscope images confirm the homogeneous dispersion and exfoliation state of FGO–AHP in the PS matrix. Incorporating FGO–AHP significantly improves the thermal behavior and fire safety performance of PS. By incorporating 5 wt% FGO–AHP, the maximum mass loss rate (MMLR) in air, total heat release (THR), and maximum smoke density value (D_smax) of PS nanocomposite achieve a reduction of 53.1%, 23.4%, and 50.9%, respectively, as compared to the pure PS. In addition, thermogravimetry–Fourier transform infrared (TG–FTIR) results indicate that introducing FGO–AHP notably inhibits the evolution of volatile products from PS decomposition. Further, scanning electron microscopy (SEM), FTIR, and Raman spectroscopy were employed to investigate the char residue of PS nanocomposite samples, elaborating the flame-retardant mechanism in PS/FGO–AHP nanocomposites. Full article

(This article belongs to the Special Issue Advances in Flame Retardant Polymeric Materials and Composites)

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24 pages, 4435 KiB

Open AccessArticle

Parameter-Independent Deformation Behaviour of Diagonally Reinforced Doubly Re-Entrant Honeycomb

by Levente Széles, Richárd Horváth and Mihály Réger

Polymers 2024, 16(21), 3082; https://doi.org/10.3390/polym16213082 - 31 Oct 2024

Viewed by 434

Abstract

In this study, a novel unit cell design is proposed, which eliminates the buckling tendency of the auxetic honeycomb. The novel unit cell design is a more balanced, diagonally reinforced doubly re-entrant auxetic honeycomb structure (x-reinforced auxetic honeycomb for short). We investigated and [...] Read more.

In this study, a novel unit cell design is proposed, which eliminates the buckling tendency of the auxetic honeycomb. The novel unit cell design is a more balanced, diagonally reinforced doubly re-entrant auxetic honeycomb structure (x-reinforced auxetic honeycomb for short). We investigated and compared this novel unit cell design against a wide parameter range. Compression tests were carried out on specimens 3D-printed with a special, unique, flexible but tough resin mixture. The results showed that the additional, centrally pronounced reinforcements resulted in increased deformation stability; parameter-independent, non-buckling deformation behaviour is achieved; however, the novel structure is no longer auxetic. Mechanical properties, such as compression resistance and energy absorption capability, also increased significantly—An almost four times increase can be observed. In contrast to the deformation behaviour (which became predictable and constant), the mechanical properties can be precisely adjusted for the desired application. This novel structure was also investigated in a highly accurate, validated finite element environment, which showed that critical stress values are formed in well-supported regions, meaning that critical failure is unlikely. Our novel lattice unit cell design elevated the auxetic honeycomb to the realm of modern, high performance and widely applicable lattice structures. Full article

(This article belongs to the Special Issue Polymer-Based Metamaterials and Metastructures)

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20 pages, 5233 KiB

Open AccessArticle

Creation of Composite Aerogels Consisting of Activated Carbon and Nanocellulose Blended with Cross-Linked Biopolymers: Application as Ethylene Scavengers

by Asadullah, Kittaporn Ngiwngam, Jaejoon Han, Pornchai Rachtanapun, Rafael Auras, Thomas Karbowiak, Duangjai Noiwan, Masubon Thongngam and Wirongrong Tongdeesoontorn

Polymers 2024, 16(21), 3081; https://doi.org/10.3390/polym16213081 - 31 Oct 2024

Viewed by 543

Abstract

This study involved producing aerogels using activated carbon (AC) and nanocellulose (NC). Two distinct structured composites, AC composite aerogel (ACCA) and NC composite aerogel (NCCA), were developed by separately mixing AC and NC with identical proportions of cross-linked biopolymers: hydroxypropyl methylcellulose (HPMC), methylcellulose [...] Read more.

This study involved producing aerogels using activated carbon (AC) and nanocellulose (NC). Two distinct structured composites, AC composite aerogel (ACCA) and NC composite aerogel (NCCA), were developed by separately mixing AC and NC with identical proportions of cross-linked biopolymers: hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), and chitosan (C). These aerogels were evaluated for their capability to adsorb ethylene gas through batch experiments, while the physical and chemical characteristics were thoroughly examined to determine their feasibility of removing ethylene. The resulting ACCA and NCCA aerogels exhibited low densities of 0.094 g cm⁻³ and 0.077 g cm⁻³, respectively, coupled with high porosity ranging between 95 and 96%. During the ethylene adsorption test, NCCA exhibited superior ethylene removal rates (~14.88–16.77 mL kg⁻¹) compared to ACCA (~13.57–14.97 mL kg⁻¹). Specifically, NCCA achieved a removal efficiency of 83.86% compared to 74.64% for ACCA. Kinetic model fitting yielded high R² values ranging from 0.97 to 0.98 with the Lagergren kinetic model. These findings suggest the potential of composite aerogels to be incorporated into food packaging materials for dynamic ethylene capture, independent of environmental conditions, thereby providing promising routes for further development. Full article

(This article belongs to the Special Issue Functional Polymers: Interaction, Surface, Processing and Applications: 2nd Edition)

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18 pages, 3318 KiB

Open AccessArticle

Biochar as a UV Stabilizer: Its Impact on the Photostability of Poly(butylene succinate) Biocomposites

by Katerina Papadopoulou, Nina Maria Ainali, Ondřej Mašek and Dimitrios N. Bikiaris

Polymers 2024, 16(21), 3080; https://doi.org/10.3390/polym16213080 - 31 Oct 2024

Viewed by 529

Abstract

In the present study, biocomposite materials were created by incorporating biochar (BC) at rates of 1, 2.5, and 5 wt.% into a poly(butylene succinate) (PBSu) matrix using a two-stage melt polycondensation procedure in order to provide understanding of the aging process. The biocomposites [...] Read more.

In the present study, biocomposite materials were created by incorporating biochar (BC) at rates of 1, 2.5, and 5 wt.% into a poly(butylene succinate) (PBSu) matrix using a two-stage melt polycondensation procedure in order to provide understanding of the aging process. The biocomposites in film form were exposed to UV irradiation for 7, 14, and 21 days. Photostability was examined by several methods, such as Fourier transform infrared spectroscopy (FTIR), which proved that new carbonyl and hydroxyl groups were formed during UV exposure. Moreover, Differential Scanning Calorimetry (DSC) measurements were employed to record the apparent UV effect in their crystalline morphology and thermal transitions. According to the molecular weight measurements of composites, it was apparent that by increasing the biochar content, the molecular weight decreased at a slower rate. Tensile strength tests were performed to evaluate the deterioration of their mechanical properties during UV exposure, while Scanning Electron Microscopy (SEM) images illustrated the notable surface alternations. Cracks were formed at higher UV exposure times, to a lesser extent in PBSu/BC composites than in neat PBSu. Furthermore, the mechanism of the thermal degradation of neat PBSu and its biocomposites prior to and upon UV exposure was studied by Pyrolysis–Gas Chromatography/Mass Spectrometry (Py–GC/MS). From all the obtained results it was proved that biochar can be considered as an efficient UV-protective additive to PBSu, capable of mitigating photodegradation. Full article

(This article belongs to the Special Issue Functional Hybrid Polymeric Composites, 2nd Edition)

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15 pages, 5316 KiB

Open AccessArticle

Study of Polysulfone-Impregnated Hydroxyapatite for Ultrafiltration in Whey Protein Separation

by Tutik Sriani, Muslim Mahardika, Budi Arifvianto, Farazila Yusof, Yudan Whulanza, Gunawan Setia Prihandana and Ario Sunar Baskoro

Polymers 2024, 16(21), 3079; https://doi.org/10.3390/polym16213079 - 31 Oct 2024

Viewed by 495

Abstract

Polysulfone (Psf) ultrafiltration flat-sheet membranes were modified with hydroxyapatite (HA) powder during preparation using the wet-phase inversion method. HA was incorporated to enhance the protein separation capabilities. The asymmetric Psf membranes were synthesized using NMP as the solvent. Through Scanning Electron Microscopy (SEM) [...] Read more.

Polysulfone (Psf) ultrafiltration flat-sheet membranes were modified with hydroxyapatite (HA) powder during preparation using the wet-phase inversion method. HA was incorporated to enhance the protein separation capabilities. The asymmetric Psf membranes were synthesized using NMP as the solvent. Through Scanning Electron Microscopy (SEM) analysis, it was revealed that HA was distributed across the membrane. Incorporating HA led to higher flux, the improved rejection of protein, and enhanced surface hydrophilicity. The permeability flux increased with HA concentration, peaking at 0.3 wt.%, resulting in a 38% improvement to 65 LMH/bar. Whey protein separation was evaluated using the model proteins BSA and lysozyme, representing α-Lactalbumin. The results of protein rejection for the blend membranes indicated that the rejection rates for BSA and lysozyme increased to 97.2% and 73%, respectively. Both the native and blend membranes showed similar BSA rejection rates; however, the blend membranes demonstrated better performance in lysozyme separation, indicating superior selectivity compared to native membranes. The modified membranes exhibited improved hydrophilicity, with water contact angles decreasing from 66° to 53°, alongside improved antifouling properties, indicated by a lower flux decline ratio value. This simple and economical modification method enhances permeability without sacrificing separation efficiency, hence facilitating the scalability of membrane production in the whey protein separation industry. Full article

(This article belongs to the Special Issue Multifunctional Polymer Composite Materials)

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13 pages, 5151 KiB

Open AccessArticle

Enhancement of the Elastocaloric Performance of Natural Rubber by Forced Air Convection

by Emma Valdés, Enric Stern-Taulats, Nicolas Candau, Lluís Mañosa and Eduard Vives

Polymers 2024, 16(21), 3078; https://doi.org/10.3390/polym16213078 - 31 Oct 2024

Viewed by 380

Abstract

We study the enhancement of the elastocaloric effect in natural rubber by using forced air convection to favour heat extraction during the elongation stage of a stretching–unstretching cycle. Elastocaloric performance is quantified by means of the adiabatic undercooling that occurs after fast removal [...] Read more.

We study the enhancement of the elastocaloric effect in natural rubber by using forced air convection to favour heat extraction during the elongation stage of a stretching–unstretching cycle. Elastocaloric performance is quantified by means of the adiabatic undercooling that occurs after fast removal of the stress, measured by infrared thermography. To ensure accuracy, spatial averaging on thermal maps of the sample surface is performed since undercooled samples display heterogeneities caused by various factors. The influence of the stretching velocity and the air velocity is analysed. The findings indicate that there is an optimal air velocity that maximises adiabatic undercooling, with stretching velocities needing to be high enough to enhance cooling power. Our experiments allowed the characterisation of the dependence of the Newton heat transfer coefficient on the air convection velocity, which revealed an enhancement up to 600% for air velocities around 4 m/s. Full article

(This article belongs to the Section Polymer Applications)

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17 pages, 3232 KiB

Open AccessArticle

Evaluation of Blended Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) Properties Containing Various 3HHx Monomers

by Nara Shin, Su Hyun Kim, Jinok Oh, Suwon Kim, Yeda Lee, Yuni Shin, Suhye Choi, Shashi Kant Bhatia, Jong-Min Jeon, Jeong-Jun Yoon, Jeong Chan Joo and Yung-Hun Yang

Polymers 2024, 16(21), 3077; https://doi.org/10.3390/polym16213077 - 31 Oct 2024

Viewed by 482

Abstract

Polyhydroxyalkanoate (PHA), specifically poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx), PHBHHx) with physical properties governed by the 3-hydroxyhexanoate (3HHx) mole fraction, is a promising bioplastic. Although engineered strains used to produce P(3HB-co-3HHx) with various 3HHx mole contents and fermentation techniques have been [...] Read more.

Polyhydroxyalkanoate (PHA), specifically poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx), PHBHHx) with physical properties governed by the 3-hydroxyhexanoate (3HHx) mole fraction, is a promising bioplastic. Although engineered strains used to produce P(3HB-co-3HHx) with various 3HHx mole contents and fermentation techniques have been studied, mass production with specific 3HHx fractions and monomers depends on the batch, supply of substrates, and strains, resulting in the time-consuming development of strains and complex culture conditions for P(3HB-co-3HHx). To overcome these limitations, we blended poly(3-hydroxybutyrate) [(P(3HB), produced from C. necator H16] and P(3HB-co-20 mol%3HHx) [from C. necator 2668/pCB81] to prepare films with various 3HHx contents. We evaluated the molecular weight and physical, thermal, and mechanical properties of these films and confirmed the influence of the 3HHx monomer content on the mechanical and thermal properties as well as degradability of the blended P(3HB-co-3HHx) films containing various 3HHx mole fractions, similar to that of original microbial-based P(3HB-co-3HHx). Moreover, the degradation rate analyzed via Microbulbifer sp. was >76% at all blending ratios within 2 days, whereas a weaker effect of the 3HHx mole fraction of the blended polymer on degradation was observed. P(3HB-co-3HHx) could be produced via simple blending using abundantly produced P(3HB) and P(3HB-co-20 mol%HHx), and the resulting copolymer is applicable as a biodegradable plastic. Full article

(This article belongs to the Special Issue Bio-Based and Biodegradable Polymers: Synthesis, Characterization and Applications)

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19 pages, 10502 KiB

Open AccessArticle

Effects of BET Surface Area and Silica Hydrophobicity on Natural Rubber Latex Foam Using the Dunlop Process

by Danvanichkul Assadakorn, Gongxu Liu, Kuanfa Hao, Lichen Bai, Fumin Liu, Yuan Xu, Lei Guo and Haichao Liu

Polymers 2024, 16(21), 3076; https://doi.org/10.3390/polym16213076 - 31 Oct 2024

Viewed by 507

Abstract

To reinforce natural rubber latex foam, fumed silica and precipitated silica are introduced into latex foam prepared using the Dunlop process as fillers. Four types of silica, including Aerosil 200 (hydrophilic fumed silica), Reolosil DM30, Aerosil R972 (hydrophobic fumed silica), and Sipernat 22S [...] Read more.

To reinforce natural rubber latex foam, fumed silica and precipitated silica are introduced into latex foam prepared using the Dunlop process as fillers. Four types of silica, including Aerosil 200 (hydrophilic fumed silica), Reolosil DM30, Aerosil R972 (hydrophobic fumed silica), and Sipernat 22S (precipitated silica), are investigated. The latex foam with added silica presents better mechanical and physical properties compared with the non-silica foam. The hydrophobic nature of the fumed silica has better dispersion in natural rubber compared to hydrophilic silica. The specific surface area of silica particles (BET) also significantly influences the properties of the latex foam, with larger specific surface areas resulting in better dispersity in the rubber matrix. It was observed that exceeding 2 phr led to difficulties in the foaming process (bulking). Furthermore, higher loading of silica also affected the rubber foam, resulting in an increased shrinkage percentage, hardness, compression set, and crosslink density. The crosslink density increased from 11.0 ± 0.2 mol/cm³ for non-silica rubber to 11.6 ± 0.6 mol/cm³ for Reolosil DM30. Reolosil DM30 also had the highest hardness, with a hardness value of 52.0 ± 2.1 IRHD, compared to 45.0 ± 1.3 IRHD for non-silica foam rubber and 48 ± 2.4 IRHD for hydrophilic fumed silica Aerosil 200. Hydrophobic fumed silica also had the highest ability to return to its original shape, with a recovery percentage of 88.0% ± 3.5% compared to the other fumed silica. Overall, hydrophobic fumed silica had better results than hydrophilic silica in both fumed and precipitated silica. Full article

(This article belongs to the Special Issue Multifunctional Polymer Composite Materials)

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10 pages, 4202 KiB

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Fabrication of Highly Sensitive Porous Polydimethylsiloxane Pressure Sensor Through Control of Rheological Properties

by Yunseok Jang, Seung-Hyun Lee, Youn-Ki Lee, Inyoung Kim, Taik-Min Lee, Sin Kwon and Boseok Kang

Polymers 2024, 16(21), 3075; https://doi.org/10.3390/polym16213075 - 31 Oct 2024

Viewed by 459

Abstract

In order to enhance the sensitivity of elastomers, pores were integrated into their structure. These pores facilitate the adjustment of thickness in response to external pressure variations, thereby improving the sensitivity of pressure sensors. Pores were introduced by emulsifying immiscible polydimethylsiloxane (PDMS) and [...] Read more.

In order to enhance the sensitivity of elastomers, pores were integrated into their structure. These pores facilitate the adjustment of thickness in response to external pressure variations, thereby improving the sensitivity of pressure sensors. Pores were introduced by emulsifying immiscible polydimethylsiloxane (PDMS) and water with a surfactant. By controlling the water content in the PDMS and water emulsion, we controlled the size, density, uniformity, and spatial distribution (2D or 3D) of the pores within the PDMS matrix. The presence of these pores significantly improved the sensitivity of PDMS under low external pressure conditions compared to high pressures. Specifically, porous PDMS exhibited approximately 10-times greater sensitivity under low-pressure conditions than non-porous PDMS. The effectiveness of porous PDMS was demonstrated through dynamic loading and unloading detection of a small Lego toy and monitoring of human heartbeats. These results highlight the efficacy of our pressure sensor based on porous PDMS, which is fabricated through a simple and cost-effective process using a PDMS and water emulsion. This approach is highly suitable for developing the ability to detect applied pressures or contact forces. Full article

(This article belongs to the Special Issue Polymers in Sensor Applications)

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20 pages, 11339 KiB

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Modeling the Dynamic Properties of Multi-Layer Glass Fabric Sandwich Panels

by Arkadiusz Charuk, Izabela Irska and Paweł Dunaj

Polymers 2024, 16(21), 3074; https://doi.org/10.3390/polym16213074 - 31 Oct 2024

Viewed by 471

Abstract

Sandwich panels are key components of many lightweight structures. They are often subjected to time-varying loads, which can cause various types of vibrations that adversely affect the functionality of the structure. That is why it is of such importance to predict the dynamic [...] Read more.

Sandwich panels are key components of many lightweight structures. They are often subjected to time-varying loads, which can cause various types of vibrations that adversely affect the functionality of the structure. That is why it is of such importance to predict the dynamic properties of both the panels and the structures made of them at the design stage. This paper presents finite element modeling of the dynamic properties (i.e., natural frequencies, mode shapes, and frequency response functions) of sandwich panels made of glass fabric impregnated with phenolic resin. The model reproducing the details of the panel structure was built using two-dimensional, quadrilateral, isoparametric plane elements. Afterwards, the model was subjected to an updating procedure based on experimentally determined frequency response functions. As a result, the average relative error for natural frequencies achieved numerically was 5.0%. Finally, a cabinet model consisting of the analyzed panels was built and experimentally verified. The relative error between the numerically and experimentally obtained natural frequencies was on average 5.9%. Full article

(This article belongs to the Special Issue Damping Mechanisms in Polymers and Polymer Composites)

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15 pages, 2776 KiB

Open AccessArticle

Biobased Compostable Plastics End-of-Life: Environmental Assessment Including Carbon Footprint and Microplastic Impacts

by Anthony Keyes, Christopher M. Saffron, Shilpa Manjure and Ramani Narayan

Polymers 2024, 16(21), 3073; https://doi.org/10.3390/polym16213073 - 31 Oct 2024

Viewed by 617

Abstract

In this paper, we examine how traditional life-cycle assessment (LCA) for bio-based and compostable plastics overlooks issues surrounding carbon sequestration and microplastic persistence. To outline biased comparisons drawn from these omitted environmental impacts, we provide, as an example, a comparative LCA for compostable [...] Read more.

In this paper, we examine how traditional life-cycle assessment (LCA) for bio-based and compostable plastics overlooks issues surrounding carbon sequestration and microplastic persistence. To outline biased comparisons drawn from these omitted environmental impacts, we provide, as an example, a comparative LCA for compostable biobased vs. non-compostable fossil-based materials. In doing so we (1) demonstrate the proper way to capture carbon footprints to make fair comparisons and (2) identify the overlooked issues of microplastics and the need for non-persistent alternatives. By ensuring accurate biogenic carbon capture, key contributors to CO₂ evolution are properly identified, allowing well-informed changes to formulations that can reduce the environmental impact of greenhouse gas emissions. In a complimentary manner, we summarize the growing research surrounding microplastic persistence and toxicity. We highlight the fundamental ability and the growing number of studies that show that industrial composting can completely mineralize certified compostable materials. This mineralization exists as a viable solution to combat microplastic persistence, currently an absent impact category in LCA. In summary, we propose a new paradigm in which the value proposition of biobased materials can be accurately captured while highlighting compostables as a solution for the increasing microplastic accumulation in the environment. Full article

(This article belongs to the Special Issue Sustainable Polymers for a Circular Economy)

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22 pages, 18117 KiB

Open AccessArticle

The Properties of Thin Films Based on Chitosan/Konjac Glucomannan Blends

by Karolina Kulka-Kamińska and Alina Sionkowska

Polymers 2024, 16(21), 3072; https://doi.org/10.3390/polym16213072 - 31 Oct 2024

Viewed by 504

Abstract

In this work, blend films were prepared by blending 2% chitosan (CS) and 0.5% konjac glucomannan (KGM) solutions. Five ratios of the blend mixture were implemented (95:5, 80:20, 50:50, 20:80, and 5:95), and a pure CS film and a pure KGM film were [...] Read more.

In this work, blend films were prepared by blending 2% chitosan (CS) and 0.5% konjac glucomannan (KGM) solutions. Five ratios of the blend mixture were implemented (95:5, 80:20, 50:50, 20:80, and 5:95), and a pure CS film and a pure KGM film were also obtained. All the polymeric films were evaluated using FTIR spectroscopy, mechanical testing, SEM and AFM imaging, thermogravimetric analyses, swelling and degradation analyses, and contact angle measurements. The CS/KGM blends were assessed for their miscibility. Additionally, the blend films’ properties were evaluated after six months of storage. The proposed blends had good miscibility in a full range of composition proportions. The blend samples, compared to the pure CS film, indicated better structural integrity. The surface structure of the blend films was rather uniform and smooth. The sample CS/KGM 20:80 had the highest roughness value (Rq = 12.60 nm). The KGM addition increased the thermal stability of films. The blend sample CS/KGM 5:95 exhibited the greatest swelling ability, reaching a swelling degree of 946% in the first fifteen minutes of the analysis. Furthermore, the addition of KGM to CS improved the wettability of the film samples. As a result of their good mechanical properties, surface characteristics, and miscibility, the proposed CS/KGM blends are promising materials for topical biomedical and cosmetic applications. Full article

(This article belongs to the Special Issue Biopolymers and Biodegradable Polymers: Synthesis, Properties, Application and Degradation Behavior)

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Polymers, Volume 16, Issue 21 (November-1 2024) – 150 articles

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