Journal Description
Polymers
Polymers
is an international, peer-reviewed, open access journal of polymer science published semimonthly online by MDPI. Belgian Polymer Group (BPG), European Colloid & Interface Society (ECIS), National Interuniversity Consortium of Materials Science and Technology (INSTM) and North American Thermal Analysis Society (NATAS) are affiliated with Polymers and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Ei Compendex, PubMed, PMC, FSTA, CAPlus / SciFinder, Inspec, and other databases.
- Journal Rank: JCR - Q1 (Polymer Science) / CiteScore - Q1 (General Chemistry )
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 13.7 days after submission; acceptance to publication is undertaken in 2.9 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in MDPI journals, in appreciation of the work.
- Testimonials: See what our authors and editors say about Polymers.
Impact Factor:
4.7 (2023);
5-Year Impact Factor:
4.9 (2023)
Latest Articles
Nanostructured Carbon Fibres (NCF): Fabrication and Application in Supercapacitor Electrode
Polymers 2024, 16(13), 1859; https://doi.org/10.3390/polym16131859 (registering DOI) - 28 Jun 2024
Abstract
A facile interconnected nanofibre electrode material derived from polybenzimidazol (PBI) was fabricated for a supercapacitor using a centrifugal spinning technique. The PBI solution in a mixture of dimethyl acetamide (DMA) and N, N-dimethylformamide (DMF) was electrospun to an interconnection of fine nanofibres. The
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A facile interconnected nanofibre electrode material derived from polybenzimidazol (PBI) was fabricated for a supercapacitor using a centrifugal spinning technique. The PBI solution in a mixture of dimethyl acetamide (DMA) and N, N-dimethylformamide (DMF) was electrospun to an interconnection of fine nanofibres. The as-prepared material was characterised by using various techniques, which include scanning electron microscopy (SEM), X-ray diffractometry (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) among others. The specific surface area of the interconnected NCF material was noticed to be around 49 m2 g−1. Electrochemical properties of the material prepared as a single-electrode are methodically studied by adopting cyclic voltammetry, electrochemical impedance spectroscopy, and constant-current charge–discharge techniques. A maximum specific capacitance of 78.4 F g−1 was observed for the electrode at a specific current of 0.5 A g−1 in a 2.5 M KNO3 solution. The electrode could also retain 96.7% of its initial capacitance after a 5000 charge–discharge cycles at 5 A g−1. The observed capacitance and good cycling stability of the electrode are supported by its specific surface area, pore volume, and conductivity. The results obtained for this material indicate its potential as suitable candidate electrode for supercapacitor application.
Full article
(This article belongs to the Special Issue Advances in Polymer Applied in Batteries and Capacitors)
Open AccessArticle
Odor Fingerprinting of Chitosan and Source Identification of Commercial Chitosan: HS-GC-IMS, Multivariate Statistical Analysis, and Tracing Path Study
by
Jin-Shuang Guo, Gang Lu, Fu-Lai Song, Ming-Yu Meng, Yu-Hao Song, Hao-Nan Ma, Xin-Rui Xie, Yi-Jia Zhu, Song He and Xue-Bo Li
Polymers 2024, 16(13), 1858; https://doi.org/10.3390/polym16131858 (registering DOI) - 28 Jun 2024
Abstract
Chitosan samples were prepared from the shells of marine animals (crab and shrimp) and the cell walls of fungi (agaricus bisporus and aspergillus niger). Fourier-transform infrared spectroscopy (FT-IR) was used to detect their molecular structures, while headspace-gas chromatography–ion mobility spectrometry (HS-GC-IMS) was employed
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Chitosan samples were prepared from the shells of marine animals (crab and shrimp) and the cell walls of fungi (agaricus bisporus and aspergillus niger). Fourier-transform infrared spectroscopy (FT-IR) was used to detect their molecular structures, while headspace-gas chromatography–ion mobility spectrometry (HS-GC-IMS) was employed to analyze their odor composition. A total of 220 volatile organic compounds (VOCs), including esters, ketones, aldehydes, etc., were identified as the odor fingerprinting components of chitosan for the first time. A principal component analysis (PCA) revealed that chitosan could be effectively identified and classified based on its characteristic VOCs. The sum of the first three principal components explained 87% of the total variance in original information. An orthogonal partial least squares discrimination analysis (OPLS-DA) model was established for tracing and source identification purposes, demonstrating excellent performance with fitting indices R2X = 0.866, R2Y = 0.996, Q2 = 0.989 for independent variable fitting and model prediction accuracy, respectively. By utilizing OPLS-DA modeling along with a heatmap-based tracing path study, it was found that 29 VOCs significantly contributed to marine chitosan at a significance level of VIP > 1.00 (p < 0.05), whereas another set of 20 VOCs specifically associated with fungi chitosan exhibited notable contributions to its odor profile. These findings present a novel method for identifying commercial chitosan sources, which can be applied to ensure biological safety in practical applications.
Full article
(This article belongs to the Section Biomacromolecules, Biobased and Biodegradable Polymers)
Open AccessArticle
Effects of Testing Methods and Sample Configuration on the Flexural Properties of Extruded Polystyrene
by
Hiroshi Yoshihara, Masahiro Yoshinobu and Makoto Maruta
Polymers 2024, 16(13), 1857; https://doi.org/10.3390/polym16131857 (registering DOI) - 28 Jun 2024
Abstract
Extruded polystyrene (XPS) is frequently used in the construction of many different structures. Therefore, it is necessary to appropriately characterize its mechanical properties to ensure the safety of said structures. Among the available characterization tests, static bending tests are simple and easy to
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Extruded polystyrene (XPS) is frequently used in the construction of many different structures. Therefore, it is necessary to appropriately characterize its mechanical properties to ensure the safety of said structures. Among the available characterization tests, static bending tests are simple and easy to perform; owing to these characteristics, they should be performed more frequently than other tests. In static bending tests on XPS, there are several challenges owing to the high flexibility of XPS, and the chosen testing method and sample configuration affect the accuracy of characterization. For cellular plastics, including XPS, three-point bending (TPB) test methods are standardized by the International Organization for Standardization (ISO) and Japanese Industrial Standards (JIS) as in ISO 1209-2:2007 and JIS K 7221-2:2006, respectively, where the sample configurations are determined. Therefore, TPB tests of cellular plastics have been conventionally performed based on these standardized methods to characterize the bending properties. In contrast, investigations on the effects of testing methods and sample configurations have often been neglected due to the existence of these standardized methods. However, to characterize the bending properties of XPS accurately, the effects of the testing method and sample configuration must be examined in detail. In this study, three bending properties (Young’s modulus, proportional limit stress, and bending strength) of samples cut from an XPS panel were determined using three-point bending (TPB), four-point bending (FPB), and compression bending (CB) tests with varying sample span/depth ratios from 5 to 50 at intervals of 5, and statistical analyses were performed to determine the relevance of the tests. The effect of sample configuration on Young’s modulus could be reduced when the span/depth ratio range was 25–50, 25–50, and 15–50 in the TPB, FPB, and CB tests, respectively, whereas that on the proportional limit stress was reduced in the span/depth ratio range of 5–50, 20–50, and 15–50 in the TPB, FPB, and CB tests, respectively. Additionally, the effect on the bending strength was reduced when the span/depth ratio range was 5–50, 20–50, and 5–50 in the TPB, FPB, and CB tests, respectively. Therefore, these results suggest that the TPB and CB tests were more feasible than the FPB test when the span/depth ratio was determined as being 25–50 and 15–50, respectively. However, clear differences were observed in the sample bending properties determined in these tests. In light of these findings, further studies should be conducted to elucidate these differences.
Full article
(This article belongs to the Section Polymer Processing and Engineering)
Open AccessArticle
Study on the Performance of Aniline Electrodeposited on MnO2 Nanowire as an Anode for Sodium-Ion Batteries
by
Dandan Ma, Xiangyu Yin, Xinyi Li, Xiangge Qin and Meili Qi
Polymers 2024, 16(13), 1856; https://doi.org/10.3390/polym16131856 (registering DOI) - 28 Jun 2024
Abstract
Manganese dioxide is an ideal anode for sodium-ion batteries due to its rich crystal shapes. However, its low conductivity, low reversible discharge capacity, slow diffusion kinetics, and poor cyclic stability limit its potential for industrial application. The design of manganese dioxide (MnO2
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Manganese dioxide is an ideal anode for sodium-ion batteries due to its rich crystal shapes. However, its low conductivity, low reversible discharge capacity, slow diffusion kinetics, and poor cyclic stability limit its potential for industrial application. The design of manganese dioxide (MnO2) with various morphologies, such as nanowires, nanorods, and nanoflowers, has proven effective in enhancing its electrochemical performance. Stacking nanowire structures is of interest as they increase the open space by forming an interconnected network, thus facilitating favorable diffusion pathways for sodium ions. Concurrently, the substantial increase in the electrolyte contact area efficiently mitigates the strain induced by the volume expansion associated with the repetitive migration and insertion of sodium ions. Based on previous research, this work presents the structural design of flexible MnO2/polyaniline (MnO2/PANI) nanowires assembled on carbon cloth (CC), an innovation in MnO2 modification. Compared to conventional MnO2 nanowires, the MnO2/PANI nanowires exhibit enhanced structural stability and improved dynamic performance, thereby marking a significant advancement in their material properties. This MnO2/PANI composite exhibits a rate capacity of approximately 200 mA h g−1 after 60 cycles at a current density of 0.1 A g−1, and maintains a rate capacity of 182 mA h g−1 even after 200 cycles under the same current density. This study not only provides new insights into the underlying mechanisms governing energy storage in MnO2/PANI nanowires but also paves the way for their further development and optimization as anodes for sodium-ion batteries, thereby opening up fresh avenues for research and application.
Full article
(This article belongs to the Section Polymer Applications)
Open AccessArticle
Ion Release and Apatite Formation of Resin Based Pit and Fissure Sealants Containing 45S5 Bioactive Glass
by
Ji-Won Choi, A Ruem Han and Song-Yi Yang
Polymers 2024, 16(13), 1855; https://doi.org/10.3390/polym16131855 (registering DOI) - 28 Jun 2024
Abstract
The purpose of this study was to evaluate a resin based pit and fissure sealant containing 45S5 bioactive glass (BAG) by examining its ion release, pH variation, and apatite-forming properties. To prepare the experimental materials, 45S5 BAG, used as a filler, was incorporated
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The purpose of this study was to evaluate a resin based pit and fissure sealant containing 45S5 bioactive glass (BAG) by examining its ion release, pH variation, and apatite-forming properties. To prepare the experimental materials, 45S5 BAG, used as a filler, was incorporated into the light curable resin matrix at concentrations of 0 (control), 12.5, 37.5, and 50.0 wt.%. Ion release, pH variation, and apatite formation (Raman spectrometer and scanning electron microscopy-energy-dispersive X-ray spectrometry measurements) were performed. While no ions were released from the control group, the experimental groups containing 45S5 BAG showed an increased release of Ca and P ions with increasing amounts of 45S5 BAG (p < 0.05). The pH of the experimental group remained high and was significantly different from the control group (p < 0.05). Unlike the control group, it was confirmed that the apatite peak was formed in the 50.0 wt.% BAG group for 90 days, and the apatite layer consisting of Ca and P was deposited on the surface. Thus, a resin based pit and fissure sealant containing 45S5 BAG is a promising material for preventing secondary caries by releasing ions and forming apatite.
Full article
(This article belongs to the Special Issue Resin Additives—Spices for Polymers)
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Open AccessArticle
Preparation and Properties of Multi-Responsive Liquid Crystalline Poly(urethane-acrylate)s and Its Composite Membranes
by
Liming Zhou, Ziwen Wang, Lijun Gao, Hongcheng Yang and Shaoming Fang
Polymers 2024, 16(13), 1854; https://doi.org/10.3390/polym16131854 (registering DOI) - 28 Jun 2024
Abstract
In this work, a kind of side chain liquid crystalline poly(urethane-acrylate)s was synthesized by free polymerization based on self-made liquid crystalline monomers, and a series of liquid crystalline polyurethane/shape memory polyurethane composite membranes were prepared by electrospinning. The synthesized liquid crystalline poly(urethane-acrylate)s have
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In this work, a kind of side chain liquid crystalline poly(urethane-acrylate)s was synthesized by free polymerization based on self-made liquid crystalline monomers, and a series of liquid crystalline polyurethane/shape memory polyurethane composite membranes were prepared by electrospinning. The synthesized liquid crystalline poly(urethane-acrylate)s have excellent thermal stability. Due to the regular arrangement of azobenzene on the side chains, polymers can rapidly undergo a photoinduced transition from trans-isomerism to cis-isomerism in THF solution and restore reversible configurational changes under visible light. The composite membranes prepared by electrospinning can also undergo photoinduced deformation within 6 s, and the deformation slowly returns under visible light. Meanwhile, the composites have shape memory, and after deformation caused by stretching, the membranes can quickly recover their original shape under thermal stimulation. These results indicate that the composites have triple response performances of photoinduced deformation, photo-, and thermal recovery.
Full article
(This article belongs to the Section Polymer Membranes and Films)
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Graphical abstract
Open AccessArticle
Investigation on the Biaxial Flexural Strength of Universal Shade Resin-Based Composites
by
Keiko Sakuma, Taku Horie, Takafumi Kishimoto, Mayumi Maesako, Shigetaka Tomoda, Morioki Fujitani and Akimasa Tsujimoto
Polymers 2024, 16(13), 1853; https://doi.org/10.3390/polym16131853 (registering DOI) - 28 Jun 2024
Abstract
The biaxial flexural strength of universal shade and conventional dental resin-based composites before and after alkaline degradation was investigated. Disk samples were prepared from these resin-based composites, and some of the specimens were immersed in 0.1 M NaOH solution to create deteriorated samples.
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The biaxial flexural strength of universal shade and conventional dental resin-based composites before and after alkaline degradation was investigated. Disk samples were prepared from these resin-based composites, and some of the specimens were immersed in 0.1 M NaOH solution to create deteriorated samples. The biaxial flexural strength of the samples before and after the alkaline degradation test was measured and statistically tested. The fracture surfaces after the biaxial flexural test were observed using a scanning electron microscope. The results showed that the biaxial flexural strength of the paste-type universal shade resin-based composite before alkaline degradation was significantly (19%) higher than that of the conventional type, but no difference was observed between the materials after alkaline degradation. On the other hand, the biaxial flexural strength of the flowable universal shade resin-based composites was significantly (around 35%) lower than that of the conventional composite, with or without degradation. Although, for paste-type materials, the biaxial flexural strength of universal shade resin-based composites was higher than that of conventional resin-based composites before alkaline degradation, after degradation the two materials showed similar values. For flowable materials, the biaxial flexural strength of universal shade resin-based composites was lower than that of conventional resin-based composites regardless of the presence or absence of degradation processes. These results suggest that some caution should be used when deciding whether to use flowable universal shade resin-based composite to fill a cavity.
Full article
(This article belongs to the Special Issue Polymers and Polymer Composites for Dental Application)
Open AccessArticle
Machine Learning in the Analysis of the Mechanical Shredding Process of Polymer Recyclates
by
Izabela Rojek, Marek Macko and Dariusz Mikołajewski
Polymers 2024, 16(13), 1852; https://doi.org/10.3390/polym16131852 (registering DOI) - 28 Jun 2024
Abstract
Artificial intelligence methods and techniques creatively support the processes of developing and improving methods for selecting shredders for the processing of polymer materials. This allows to optimize the fulfillment of selection criteria, which may include not only indicators related to shredding efficiency and
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Artificial intelligence methods and techniques creatively support the processes of developing and improving methods for selecting shredders for the processing of polymer materials. This allows to optimize the fulfillment of selection criteria, which may include not only indicators related to shredding efficiency and recyclate quality but also energy consumption. The aim of this paper is to select methods of analysis based on artificial intelligence (AI) with independent rule extraction, i.e., data-based methods (machine learning—ML). This study took into account real data sets (feature matrix 1982 rows × 40 columns) describing the shredding process, including energy consumption used to optimize the parameters for the energy efficiency of the shredder. Each of the 1982 records in a .csv file (feature vector) has 40 numbers divided by commas. The data were divided into a learning set (70% of the data), a testing set (20% of the data), and a validation set (10% of the data). Cross-validation showed that the best model was LbfgsLogisticRegressionOva (0.9333). This promotes the development of the basis for an intelligent shredding methodology with a high level of innovation in the processing and recycling of polymer materials within the Industry 4.0 paradigm.
Full article
(This article belongs to the Special Issue Recycling of Engineering Polymers: Process and Physico-Chemical Changes)
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Open AccessArticle
Optimization of Laminated Bio-Polymer Fabrication for Food Packaging Application: A Sustainable Plasma-Activated Approach
by
Giacomo Foli, Filippo Capelli, Mariachiara Grande, Stefano Tagliabue, Matteo Gherardi and Matteo Minelli
Polymers 2024, 16(13), 1851; https://doi.org/10.3390/polym16131851 (registering DOI) - 28 Jun 2024
Abstract
The current level of packaging consumption imposes a need to fabricate single-use food packaging with renewable and compostable materials, such as bio-polyesters (e.g., polylactic acid, PLA and polybutylene succinate, PBS) or cellulose, but their use is still problematic. Fabrication of bio-compostable composites can
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The current level of packaging consumption imposes a need to fabricate single-use food packaging with renewable and compostable materials, such as bio-polyesters (e.g., polylactic acid, PLA and polybutylene succinate, PBS) or cellulose, but their use is still problematic. Fabrication of bio-compostable composites can specifically address impeding challenges, and adhesive lamination, achieved with compostable glue, is becoming more and more popular with respect to the less versatile hot lamination. In this context, plasma activation, a chemical-free oxidation technique of a material’s surface, is used to increase the affinity of three different biomaterials (cellulose, PLA and PBS) toward a compostable polyurethane adhesive to decrease its amount by gluing bio-polyesters to cellulose. Optical Microscopy reveals activation conditions that do not affect the integrity of the materials, while Water Contact Analyses confirm the activation of the surfaces, with contact angles decreased to roughly 50 deg in all cases. Unexpectedly, ζ-potential analyses and subtractive infrared spectroscopy highlight how the activation performed superficially etches cellulose, while for both PLA and PBS, a general decrease in surface potential and an increase in superficial hydroxyl group populations confirm the achievement of the desired oxidation. Thus, we rationalize continuous activation conditions to treat PLA and PBS and to glue them to neat cellulose. While no beneficial effect is observed with activated PLA, bi-laminate composites fabricated with activated PBS fulfill the benchmark for adhesion strength using less than before, while oxygen permeation analyses exclude plasma-induced etching even at a nanoscale.
Full article
(This article belongs to the Special Issue Biopolymers from Renewable Sources and Their Applications II)
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Open AccessArticle
Spectroscopic Benchmarks by Machine Learning as Discriminant Analysis for Unconventional Italian Pictorialism Photography
by
Claudia Scatigno, Lorenzo Teodonio, Eugenia Di Rocco and Giulia Festa
Polymers 2024, 16(13), 1850; https://doi.org/10.3390/polym16131850 (registering DOI) - 28 Jun 2024
Abstract
Up to the 1930s, the Italian pictorialism movement dominated photography, and many handcrafted procedures started appearing. Each operator had his own working method and his own secrets to create special effects that moved away from the standard processes. Here, a methodology that combines
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Up to the 1930s, the Italian pictorialism movement dominated photography, and many handcrafted procedures started appearing. Each operator had his own working method and his own secrets to create special effects that moved away from the standard processes. Here, a methodology that combines X-ray fluorescence and infrared analysis spectroscopy with unsupervised learning techniques was developed on an unconventional Italian photographic print collection (the Piero Vanni Collection, 1889–1939) to unveil the artistic technique by the extraction of spectroscopic benchmarks. The methodology allowed the distinction of hidden elements, such as iodine and manganese in silver halide printing, or highlighted slight differences in the same printing technique and unveiled the stylistic practice. Spectroscopic benchmarks were extracted to identify the elemental and molecular fingerprint layers, as the oil-based prints were obscured by the proteinaceous binder. It was identified that the pigments used were silicates or iron oxide introduced into the solution or that they retraced the practice of reusing materials to produce completely different printing techniques. In general, four main groups were extracted, in this way recreating the ‘artistic palette’ of the unconventional photography of the artist. The four groups were the following: (1) Cr, Fe, K, potassium dichromate, and gum arabic bands characterized the dichromate salts; (2) Ag, Ba, Sr, Mn, Fe, S, Ba, gelatin, and albumen characterized the silver halide emulsions on the baryta layer; (3) the carbon prints were benchmarked by K, Cr, dichromate salts, and pigmented gelatin; and (4) the heterogeneous class of bromoil prints was characterized by Ba, Fe, Cr, Ca, K, Ag, Si, dichromate salts, and iron-based pigments. Some exceptions were found, such as the baryta layer being divided into gum bichromate groups or the use of albumen in silver particles suspended in gelatin, to underline the unconventional photography at the end of the 10th century.
Full article
(This article belongs to the Section Polymer Analysis and Characterization)
Open AccessArticle
Nanoindentation Response of Structural Self-Healing Epoxy Resin: A Hybrid Experimental–Simulation Approach
by
Giovanni Spinelli, Rosella Guarini, Evgeni Ivanov, Elisa Calabrese, Marialuigia Raimondo, Raffaele Longo, Liberata Guadagno and Luigi Vertuccio
Polymers 2024, 16(13), 1849; https://doi.org/10.3390/polym16131849 (registering DOI) - 28 Jun 2024
Abstract
In recent years, self-healing polymers have emerged as a topic of considerable interest owing to their capability to partially restore material properties and thereby extend the product’s lifespan. The main purpose of this study is to investigate the nanoindentation response in terms of
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In recent years, self-healing polymers have emerged as a topic of considerable interest owing to their capability to partially restore material properties and thereby extend the product’s lifespan. The main purpose of this study is to investigate the nanoindentation response in terms of hardness, reduced modulus, contact depth, and coefficient of friction of a self-healing resin developed for use in aeronautical and aerospace contexts. To achieve this, the bifunctional epoxy precursor underwent tailored functionalization to improve its toughness, facilitating effective compatibilization with a rubber phase dispersed within the host epoxy resin. This approach aimed to highlight the significant impact of the quantity and distribution of rubber domains within the resin on enhancing its mechanical properties. The main results are that pure resin (EP sample) exhibits a higher hardness (about 36.7% more) and reduced modulus (about 7% more), consequently leading to a lower contact depth and coefficient of friction (11.4% less) compared to other formulations that, conversely, are well-suited for preserving damage from mechanical stresses due to their capabilities in absorbing mechanical energy. Furthermore, finite element method (FEM) simulations of the nanoindentation process were conducted. The numerical results were meticulously compared with experimental data, demonstrating good agreement. The simulation study confirms that the EP sample with higher hardness and reduced modulus shows less penetration depth under the same applied load with respect to the other analyzed samples. Values of 877 nm (close to the experimental result of 876.1 nm) and 1010 nm (close to the experimental result of 1008.8 nm) were calculated for EP and the toughened self-healing sample (EP-R-160-T), respectively. The numerical results of the hardness provide a value of 0.42 GPa and 0.32 GPa for EP and EP-R-160-T, respectively, which match the experimental data of 0.41 GPa and 0.30 GPa. This validation of the FEM model underscores its efficacy in predicting the mechanical behavior of nanocomposite materials under nanoindentation. The proposed investigation aims to contribute knowledge and optimization tips about self-healing resins.
Full article
(This article belongs to the Special Issue Advances in Self-Healing Polymer Composites)
Open AccessArticle
A Study on the Evaluation of Thermal Insulation Performance of Cellulose-Based Silica Aerogel Composite Building Materials
by
Jeo Hwang, Yoonmi Kim, Jooyoung Park and Dongho Rie
Polymers 2024, 16(13), 1848; https://doi.org/10.3390/polym16131848 (registering DOI) - 28 Jun 2024
Abstract
Buildings utilize both inorganic and organic insulation materials to conserve energy and prevent heat loss. However, while exhibiting excellent thermal insulation performance, organic insulation materials increase the risk of fire due to the emission of intense heat and toxic smoke in the event
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Buildings utilize both inorganic and organic insulation materials to conserve energy and prevent heat loss. However, while exhibiting excellent thermal insulation performance, organic insulation materials increase the risk of fire due to the emission of intense heat and toxic smoke in the event of a fire. Conversely, inorganic insulation materials are characterized by a lower thermal insulation performance, leading to an increase in the weight of the building with extensive use. Therefore, the necessity for research into new insulation materials that address the drawbacks of existing ones, including reducing weight, enhancing fire resistance, and improving thermal insulation performance, has been recognized. This study focuses on evaluating the enhancement of the thermal insulation performance using novel building materials compared to conventional ones. The research methodology involved the incorporation of porous aerogel powders into paper-based cellulose insulation to improve its insulating properties. Samples were prepared in standard 100 × 100 mm2 panel forms. Two control groups were utilized: a pure control group, where specimens were fabricated using 100% recycled cardboard for packaging, and a mixed control group, where specimens were produced using a mixture ratio of 30 wt% ceramic binder and 40 wt% expandable graphite. Experimental group specimens were prepared by increasing the aerogel content from 200 to 1000 mL under each condition of the control groups (pure and mixed) after mixing. The thermal insulation performance of the specimens was evaluated in terms of thermal conductivity and thermal diffusivity according to ISO 22007-2 (for solids, paste, and powders). Through this study, it was found that the thermal insulation performances of the pure control and experimental groups improved by 16.66%, while the mixed control and experimental groups demonstrated a 17.06% enhancement in thermal insulation performance with the addition of aerogel.
Full article
(This article belongs to the Special Issue Recent Developments in Wood Polymer Composites)
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Open AccessArticle
Mechanical Characterization, Water Absorption, and Thickness Swelling of Lightweight Pineapple Leaf/Ramie Fabric-Reinforced Polypropylene Hybrid Composites
by
Lin Feng Ng, Mohd Yazid Yahya, Chandrasekar Muthukumar, Jyotishkumar Parameswaranpillai, Quanjin Ma, Muhammad Rizal Muhammad Asyraf and Rohah Abdul Majid
Polymers 2024, 16(13), 1847; https://doi.org/10.3390/polym16131847 (registering DOI) - 28 Jun 2024
Abstract
Fiber-reinforced composites are among the recognized competing materials in various engineering applications. Ramie and pineapple leaf fibers are fascinating natural fibers due to their remarkable material properties. This research study aims to unveil the viability of hybridizing two kinds of lignocellulosic plant fiber
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Fiber-reinforced composites are among the recognized competing materials in various engineering applications. Ramie and pineapple leaf fibers are fascinating natural fibers due to their remarkable material properties. This research study aims to unveil the viability of hybridizing two kinds of lignocellulosic plant fiber fabrics in polymer composites. In this work, the hybrid composites were prepared with the aid of the hot compression technique. The mechanical, water-absorbing, and thickness swelling properties of ramie and pineapple leaf fiber fabric-reinforced polypropylene hybrid composites were identified. A comparison was made between non-hybrid and hybrid composites to demonstrate the hybridization effect. According to the findings, hybrid composites, particularly those containing ramie fiber as a skin layer, showed a prominent increase in mechanical strength. In comparison with non-hybrid pineapple leaf fabric-reinforced composites, the tensile, flexural, and Charpy impact strengths were enhanced by 52.10%, 18.78%, and 166.60%, respectively, when the outermost pineapple leaf fiber layers were superseded with ramie fabric. However, increasing the pineapple leaf fiber content reduced the water absorption and thickness swelling of the hybrid composites. Undeniably, these findings highlight the potential of hybrid composites to reach a balance in mechanical properties and water absorption while possessing eco-friendly characteristics.
Full article
(This article belongs to the Section Polymer Composites and Nanocomposites)
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Open AccessReview
Preparation Method and Application of Porous Poly(lactic acid) Membranes: A Review
by
Jinxing Zhao, Xianggui Liu, Xuelian Pu, Zetong Shen, Wenqiang Xu and Jian Yang
Polymers 2024, 16(13), 1846; https://doi.org/10.3390/polym16131846 - 28 Jun 2024
Abstract
Porous membrane technology has garnered significant attention in the fields of separation and biology due to its remarkable contributions to green chemistry and sustainable development. The porous membranes fabricated from polylactic acid (PLA) possess numerous advantages, including a low relative density, a high
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Porous membrane technology has garnered significant attention in the fields of separation and biology due to its remarkable contributions to green chemistry and sustainable development. The porous membranes fabricated from polylactic acid (PLA) possess numerous advantages, including a low relative density, a high specific surface area, biodegradability, and excellent biocompatibility. As a result, they exhibit promising prospects for various applications, such as oil–water separation, tissue engineering, and drug release. This paper provides an overview of recent research advancements in the fabrication of PLA membranes using electrospinning, the breath-figure method, and the phase separation method. Firstly, the principles of each method are elucidated from the perspective of pore formation. The correlation between the relevant parameters and pore structure is discussed and summarized, subsequently followed by a comparative analysis of the advantages and limitations of each method. Subsequently, this article presents the diverse applications of porous PLA membranes in tissue engineering, oil–water separation, and other fields. The current challenges faced by these membranes, however, encompass inadequate mechanical strength, limited production efficiency, and the complexity of pore structure control. Suggestions for enhancement, as well as future prospects, are provided accordingly.
Full article
(This article belongs to the Special Issue Recent Trends in Polymer Membranes: Fabrication Technique, Characterization, Functionalization, and Applications in Environmental Science)
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Open AccessArticle
Repair Effect of Umbilical Cord Mesenchymal Stem Cells Embedded in Hydrogel on Mouse Insulinoma 6 Cells Injured by Streptozotocin
by
Jia Yang, Yang Liu, Minghui Wang, Shengqin Chen, Qingya Miao, Zhicong Liu, Bin Zhang and Guodong Deng
Polymers 2024, 16(13), 1845; https://doi.org/10.3390/polym16131845 - 28 Jun 2024
Abstract
Umbilical cord mesenchymal stem cells (UC-MSCs) possess the capabilities of differentiation and immune modulation, which endow them with therapeutic potential in the treatment of type 2 diabetes mellitus (T2DM). In this study, to investigate the repair mechanism of UC-MSCs in hydrogel on pancreatic
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Umbilical cord mesenchymal stem cells (UC-MSCs) possess the capabilities of differentiation and immune modulation, which endow them with therapeutic potential in the treatment of type 2 diabetes mellitus (T2DM). In this study, to investigate the repair mechanism of UC-MSCs in hydrogel on pancreatic β-cells in diabetes, mouse insulinoma 6 (MIN-6) cells damaged by streptozotocin (STZ) in vitro were used in co-culture with UC-MSCs in hydrogel (UC-MSCs + hydrogel). It was found that UC-MSCs + hydrogel had a significant repair effect on injured MIN-6 cells, which was better than the use of UC-MSCs alone (without hydrogel). After repair, the expression of superoxide dismutase (SOD) and catalase (CAT) as well as the total antioxidant capacity (T-AOC) of the repaired MIN-6 cells were increased, effectively reducing the oxidative stress caused by STZ. In addition, UC-MSCs + hydrogel were able to curb the inflammatory response by promoting the expression of anti-inflammatory factor IL-10 and reducing inflammatory factor IL-1β. In addition, the expression of both nuclear antigen Ki67 for cell proliferation and insulin-related genes such as Pdx1 and MafA was increased in the repaired MIN-6 cells by UC-MSCs + hydrogel, suggesting that the repair effect promotes the proliferation of the injured MIN-6 cells. Compared with the use of UC-MSCs alone, UC-MSCs + hydrogel exhibit superior antioxidant stress resistance against injured MIN-6 cells, better proliferation effects and a longer survival time of UC-MSCs because the porous structure and hydrophilic properties of the hydrogel could affect the growth of cells and slow down their metabolic activities, resulting in a better repair effect on the injured MIN-6 cells.
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(This article belongs to the Special Issue Biopolymers for Drug Delivery and Tissue Engineering)
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Open AccessArticle
Preload Influence on the Dynamic Properties of a Polyurethane Elastomeric Foam
by
Julen Cortazar-Noguerol, Fernando Cortés, Imanol Sarría and María Jesús Elejabarrieta
Polymers 2024, 16(13), 1844; https://doi.org/10.3390/polym16131844 - 28 Jun 2024
Abstract
Polymeric foams are widely used in engineering applications for vibration attenuation. The foams usually work preloaded and it is known that the dynamic properties and attenuation ability of these polymers depend on the preload. In this paper, experimental characterization of a polyurethane elastomeric
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Polymeric foams are widely used in engineering applications for vibration attenuation. The foams usually work preloaded and it is known that the dynamic properties and attenuation ability of these polymers depend on the preload. In this paper, experimental characterization of a polyurethane elastomeric foam is performed in a frequency range between 1 and 60 Hz, a temperature range between −60 and 30 °C and a preload range between 2 and 12 N, using a Dynamic Mechanical Analyzer. When going from the minimum to the maximum preload, results show the linear viscoelastic range increases 57%. In the frequency sweeps, the storage modulus increases 58% on average, while the loss factor remains unaffected by preload. Moreover, the glassy transition temperature of the material decreases for greater preloads. From the curve-fitting of a four-parameter fractional derivative model using the experimental data, a seven-parameter mathematical model is developed, reducing the number of parameters needed to describe the influence of frequency and preload on the dynamic properties of the material. Hence, it has been established that the relaxation time, relaxed modulus and unrelaxed modulus depend on the exponential of the squared prestress. In contrast, the fractional parameter does not depend on preload for the range under study.
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(This article belongs to the Special Issue Mechanical Behaviors and Properties of Polymer Materials)
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Open AccessArticle
Comparative Analysis of Impact Strength among Various Polymeric Materials for Orthotic Production
by
Rachel Habiba, Ana Amaro, Daniela Trindade, Carla Moura, Rui Silva, André Antão, Rui F. Martins, Cândida Malça and Ricardo Branco
Polymers 2024, 16(13), 1843; https://doi.org/10.3390/polym16131843 - 28 Jun 2024
Abstract
Orthotic devices play an important role in medical treatment, addressing various pathologies and promoting patient recovery. Customization of orthoses to fit individual patient morphologies and needs is essential for optimal functionality and patient comfort. The advent of additive manufacturing has revolutionized the biomedical
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Orthotic devices play an important role in medical treatment, addressing various pathologies and promoting patient recovery. Customization of orthoses to fit individual patient morphologies and needs is essential for optimal functionality and patient comfort. The advent of additive manufacturing has revolutionized the biomedical field, offering advantages such as cost reduction, increased personalization, and enhanced dimensional adaptability for orthotics manufacturing. This research focuses on the impact strength of nine polymeric materials printed by additive manufacturing, including an evaluation of the materials’ performance under varying conditions comprising different printing directions (vertical and horizontal) and exposure to artificial sweat for different durations (0 days, 24 days, and 189 days). The results showed that Nylon 12 is good for short-term (24 days) immersion, with absorbed energies of 78 J and 64 J for the vertical and horizontal directions, whereas Polycarbonate (PC) is good for long-term immersion (189 days), with absorbed energies of 66 J and 78 J for the vertical and horizontal directions. Overall, the findings contribute to a better understanding of the suitability of these materials for biomedical applications, considering both short-term and long-term exposure to physiological and environmental conditions.
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(This article belongs to the Section Polymer Processing and Engineering)
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Open AccessArticle
Unveiling the Impact of Gelation Temperature on the Rheological and Microstructural Properties of Type A Gelatin Hydrogels
by
Hanaa Mehdi-Sefiani, E. Chicardi, A. Romero and Victor M. Perez-Puyana
Polymers 2024, 16(13), 1842; https://doi.org/10.3390/polym16131842 - 28 Jun 2024
Abstract
Gelatin-based hydrogels have garnered significant attention in the fields of drug delivery systems and tissue engineering owing to their biodegradability, biocompatibility, elasticity, flexibility and nontoxic nature. However, there is a lack of information regarding type-A-gelatin-based hydrogels. In this sense, the main aim of
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Gelatin-based hydrogels have garnered significant attention in the fields of drug delivery systems and tissue engineering owing to their biodegradability, biocompatibility, elasticity, flexibility and nontoxic nature. However, there is a lack of information regarding type-A-gelatin-based hydrogels. In this sense, the main aim of this work was the evaluation of the properties of type-A-gelatin-based hydrogel achieved using two different gelation temperatures (4 °C and 20 °C). Thus, the main novelty of this study lies in the analysis of the impact of gelation time on the rheological and microstructural properties of type-A-gelatin-based hydrogels. Moreover, the addition of a drug was also analyzed in order to evaluate the hydrogels’ behavior as a drug delivery system. For this purpose, rheological (strain, frequency sweep tests and flow curves) and microstructural (SEM) characterizations were carried out. The results demonstrated that lowering the gelation temperature improved the rheological properties of the systems, obtaining hydrogels with an elastic modulus of 20 kPa when processing at 4 °C. On the other hand, the increase in the gelation temperature improved the critical strain of the systems at low temperatures. In conclusion, this work showed the feasibility of producing hydrogels with potential application in drug delivery with different properties, varying the testing temperature and incorporating tetracycline into their formulation.
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(This article belongs to the Section Biomacromolecules, Biobased and Biodegradable Polymers)
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Open AccessReview
Review of Recent Progress on Silicone Rubber Composites for Multifunctional Sensor Systems
by
Vineet Kumar, Md. Najib Alam and Sang Shin Park
Polymers 2024, 16(13), 1841; https://doi.org/10.3390/polym16131841 - 28 Jun 2024
Abstract
The latest progress (the year 2021–2024) on multifunctional sensors based on silicone rubber is reported. These multifunctional sensors are useful for real-time monitoring through relative resistance, relative current change, and relative capacitance types. The present review contains a brief overview and literature survey
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The latest progress (the year 2021–2024) on multifunctional sensors based on silicone rubber is reported. These multifunctional sensors are useful for real-time monitoring through relative resistance, relative current change, and relative capacitance types. The present review contains a brief overview and literature survey on the sensors and their multifunctionalities. This contains an introduction to the different functionalities of these sensors. Following the introduction, the survey on the types of filler or rubber and their fabrication are briefly described. The coming section deals with the fabrication methodology of these composites where the sensors are integrated. The special focus on mechanical and electro-mechanical properties is discussed. Electro-mechanical properties with a special focus on response time, linearity, and gauge factor are reported. The next section of this review reports the filler dispersion and its role in influencing the properties and applications of these sensors. Finally, various types of sensors are briefly reported. These sensors are useful for monitoring human body motions, breathing activity, environment or breathing humidity, organic gas sensing, and, finally, smart textiles. Ultimately, the study summarizes the key takeaway from this review article. These conclusions are focused on the merits and demerits of the sensors and are followed by their future prospects.
Full article
(This article belongs to the Special Issue Multi-Functional and Multi-Scale Aspects in Polymer Composites)
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Open AccessArticle
The Use of Polyimide as a Bonding Material to Improve the Mechanical Stability, Magnetic and Acoustic Properties of the Transformer Core Based on Amorphous Steel
by
Jolanta Nieroda, Grzegorz Kmita, Michal Kozupa, Szymon Piela and Andrzej Rybak
Polymers 2024, 16(13), 1840; https://doi.org/10.3390/polym16131840 - 28 Jun 2024
Abstract
The constantly evolving electrification also entails an increase in requirements for the effective and efficient distribution of electricity with the lowest possible power losses. Such needs can be met by highly effective electrical devices, and one of them is a transformer whose main
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The constantly evolving electrification also entails an increase in requirements for the effective and efficient distribution of electricity with the lowest possible power losses. Such needs can be met by highly effective electrical devices, and one of them is a transformer whose main component is a magnetic core. Currently, one of the soft magnetic materials used alternatively for the production of transformer cores are amorphous metal strips with competitive losses. However, to successfully use these materials, a key problem must be solved: limited mechanical stability. The presented article describes the development and application of a polyimide-based binder for efficient bonding of an amorphous metal ribbon. The layered binder was characterized using confocal microscopy, scanning electron microscopy and Raman spectroscopy, and its anticorrosion and mechanical properties were examined. As a final step, a prototype of a toroidal magnetic core bonded with the binder was manufactured and subjected to the evaluation of no-load loss and the analysis of the emitted noise. It was confirmed that the proposed polyimide binder tremendously improved the mechanical stability while reducing core losses and audible noise.
Full article
(This article belongs to the Special Issue Application of Functional Polymer Materials for Advanced Technologies)
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