Robust Strain Sensor with High Sensitivity Based on Polymer-Encapsulated Microfiber Mach–Zehnder Interferometer
Furanoate Blends for Sustainable and Flexible Packaging
Sandwich-Structured Carbon Fiber-Reinforced Composite (CFRC) for Electric Vehicle Battery Casings
Flexural Behavior of Thermoformed 3D-Printed Wrist Orthoses: Material, Infill, and Wear Condition Impacts
Fatigue Behaviour of High-Performance Green Epoxy Biocomposite Laminates Reinforced by Optimized Long Sisal Fibers

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 14.5 days after submission; acceptance to publication is undertaken in 3.4 days (median values for papers published in this journal in the first half of 2024).
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)

Imprint Information Journal Flyer Open Access ISSN: 2073-4360

Latest Articles

13 pages, 2232 KiB

Open AccessArticle

Biochar as Sustainable Filler of Recycled Polylactic Acid (PLA): A New Generation of Processable Biocomposites

by Chiara Botta, Corinna Maria Grottola, Davide Amato and Maria Rosaria Acocella

Polymers 2024, 16(23), 3347; https://doi.org/10.3390/polym16233347 (registering DOI) - 29 Nov 2024

Abstract

As an alternative to fossil-based polymers, polylactide acid (PLA) has stimulated a significant research effort in the past few years due to the demand for environmentally friendly products. Even though PLA is considered a sustainable or bio-based material, the long-term degradation in ambient conditions increases the volume of waste at end-of-life. To overcome this issue, PLA waste can be recycled to produce new manufactures; however, this approach does not always ensure the same mechanical properties as the original PLA. This study shows for the first time that adding biochar, a carbon material derived from biomass pyrolysis, enhances the processability and stability of composite recycled PLA. Composites are provided in 1, 2.5, and 5 wt% of the biochar filler, resulting in good processability, a higher modulus of up to 20%, and a higher stability to degradation in the presence of UV aging treatment with respect to the raw material. Additionally, DSC analysis shows a significant nucleation effect induced by the biochar that achieves 30% crystallinity from an essentially amorphous PLA. Full article

(This article belongs to the Special Issue Biopolymer-Based Biomimetic Scaffolds II)

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11 pages, 2507 KiB

Open AccessArticle

Enhancing Starch Film Properties Using Bacterial Nanocellulose-Stabilized Pickering Emulsions

by Natália Tavares de Almeida, André Luís Sousa Pereira, Matheus de Oliveira Barros, Adriano Lincoln Albuquerque Mattos and Morsyleide de Freitas Rosa

Polymers 2024, 16(23), 3346; https://doi.org/10.3390/polym16233346 (registering DOI) - 29 Nov 2024

Abstract

This study aimed to address issues related to hydrophilicity, barrier properties, and mechanical performance in starch-based films by incorporating Pickering emulsions stabilized with nano-fibrillated bacterial cellulose (BC). Emulsions were added to the film-forming suspension at varying concentrations (1.0%, 2.5%, 5.0%, and 7.5% v/v) for comparison. The films were evaluated using water vapor permeability (WVP), contact angle, Fourier Transform Infrared Spectroscopy (FTIR), and tensile tests. The results showed a significant reduction in film hydrophilicity, with the contact angle increasing from 49.7° ± 1.5 to 71.0° ± 1.4, and improved water vapor barrier properties, with WVP decreasing from 0.085 ± 0.04 to 0.016 ± 0.01 g·mm/h·m²·kPa. FTIR analysis confirmed the successful incorporation of the emulsion into the starch matrix. Among the tested concentrations, 2.5% provided an optimal balance, increasing hydrophobicity while maintaining mechanical strength. These findings demonstrate that Pickering emulsions are an effective strategy for enhancing the functional properties of starch films. Full article

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

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16 pages, 2697 KiB

Open AccessArticle

Effects of Different Non-Ionic Polysaccharides on the Heat-Induced Gelling Properties of Curdlan

by Guoyan Zhong, Zhaojun Wang, Qiuming Chen, Zhiyong He, Maomao Zeng, Fang Qin and Jie Chen

Polymers 2024, 16(23), 3345; https://doi.org/10.3390/polym16233345 (registering DOI) - 29 Nov 2024

Abstract

Curdlan’s application is constrained by high gelation concentration, poor water solubility, and incompatibility with other polysaccharides. To address these limitations, this study investigated the effects of different concentrations (0.05–0.3%) of non-ionic polysaccharides (pullulan (PL), locust bean gum (LBG), guar gum (GG), and konjac gum (KGM)) on the heat-induced gelling properties of curdlan. PL with no branch showed 0.3% enhanced gel hardness. LBG with a small amount of galactose residue and KGM with an acetyl group had similar effects on hardness, while GG with a large amount of galactose residue slightly weakened the mixed gel. The rheological results showed that PL had little effect on curdlan, and LBG and KGM had a positive effect on curdlan unfolding, but 0.3% GG was significantly antagonistic to curdlan. The above results implied that non-ionic polysaccharides without side chains interacted weakly with the curdlan and hardly changed the properties of curdlan. Curdlan unfolding and stable suspension were favored if the structure contained galactose or acetyl side chains that interacted with curdlan through hydrogen bonding. These results suggested an effective way to modify curdlan by strengthening the interaction of curdlan with others and weakening the hydrogen bonding of curdlan to broaden its application in food colloids. Full article

(This article belongs to the Special Issue Biopolymers: Structure-Function Relationship and Application III)

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16 pages, 6795 KiB

Open AccessArticle

Influence of Polymer Nature on Electroadhesion

by Konstantin I. Sharov, Valentina Yu. Stepanenko, Uliana V. Nikulova and Aleksey V. Shapagin

Polymers 2024, 16(23), 3344; https://doi.org/10.3390/polym16233344 (registering DOI) - 28 Nov 2024

Abstract

Electroadhesive systems are promising for creating delicate robotic manipulators operating both in the natural environment and in space conditions. Using thermosetting epoxy resin, polyurethane and polyester resin as examples, the influence of the polymers’ natures, potential differences and current strengths on electroadhesive interactions in polymer–polymer systems was studied. The investigations were carried out by recording the force of normal separation of substrates from electroadhesives using contact and contactless methods at various electrical parameters of the systems and their components. A correlation was established between the relative permittivity and the electroadhesive force. The relaxation nature of the electroadhesion phenomenon after removing the electrical voltage was revealed. The influence of the potential difference and current strength on the effect of electroadhesion for polymer substrates of various natures was established. The obtained dependencies describe the main regularities of electroadhesive interactions necessary for creating promising electroadhesive materials. Full article

(This article belongs to the Section Polymer Analysis and Characterization)

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40 pages, 2817 KiB

Open AccessReview

Recent Advances in Fire Safety of Carbon Fiber-Reinforced Epoxy Composites for High-Pressure Hydrogen Storage Tanks

by Omar Dagdag and Hansang Kim

Polymers 2024, 16(23), 3343; https://doi.org/10.3390/polym16233343 - 28 Nov 2024

Abstract

The increasing use of hydrogen as a clean energy carrier has underscored the necessity for advanced materials that can provide safe storage under extreme conditions. Carbon fiber-reinforced epoxy (CFRP) composites are increasingly utilized in various high-performance applications, including automotive, aerospace, and particularly hydrogen storage tanks, due to their exceptional strength-to-weight ratio, durability, excellent corrosion resistance, and low thermal conductivity. However, the inherent flammability of epoxy matrices poses significant safety concerns, particularly in hydrogen storage, where safety is paramount. This review paper provides a comprehensive overview of the recent progress in enhancing the fire safety of CFRP. The focus is on innovative strategies such as developing novel flame-retardant (FR) additives, intumescent coatings, and nanomaterial reinforcements. It analyzes the effectiveness of these strategies in improving the fire performance of CFRP composites, including their flame retardancy, smoke suppression, and heat release rate reduction. The review paper also explores the application of fire modeling tools to predict the fire behavior of CFRP composite hydrogen storage tanks under various fire scenarios. Additionally, the review discusses the implications of these advancements on the performance and safety of hydrogen storage tanks, highlighting both the progress made and the challenges that remain. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization II)

28 pages, 12696 KiB

Open AccessArticle

The Thermo-Oxidative Degradation of Polyurethane Open-Cell Soft Foam Investigated Through Gas Chromatography and Mass Spectrometry of Volatile Organic Compounds

by Christian Stefan Sandten, Martin Kreyenschmidt, Rolf Albach and Ursula E. A. Fittschen

Polymers 2024, 16(23), 3342; https://doi.org/10.3390/polym16233342 - 28 Nov 2024

Abstract

Polyurethane (PUR) soft foams release malodorous and potentially toxic compounds when exposed to oxidative conditions. Current chamber test methods cannot distinguish between pre-existing volatiles and those formed during oxidation, nor can they assess the formation rates of oxidation products. We subjected PUR soft foam to oxidative treatment in a continuous air flow at 120 °C. Emissions were convectively transferred from the foam to an exhaust port and analyzed using a thermodesorption–gas chromatography–mass spectrometry (TD-GC-MS) system, with external calibration employed for the quantification of selected analytes. The study identified hydroperoxide formation and degradation as key mechanisms in the breakdown of the polyether soft segments. This process predominantly produces volatiles, such as carboxylic acids, formates, acetates, alpha-hydroxy-ketones, (unsaturated) aldehydes, substituted dioxolanes and dioxanes, glycols, and allyl ethers. Volatiles associated with the degradation of the hard segments include aniline, benzoxazole, 2-methylbenzoxazole, and benzaldehyde. This experimental setup enables reproducible qualitative and quantitative analysis of volatiles formed during the oxidative degradation of PUR soft foams, providing new insights into the segment-dependent chemical pathways of the polymer’s molecular breakdown. Full article

(This article belongs to the Section Polymer Analysis and Characterization)

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23 pages, 8761 KiB

Open AccessArticle

Structural Optimization of a High-Performance Green Sandwich Made of Sisal Reinforced Epoxy Facings and Balsa Core

by Bernardo Zuccarello, Francesco Bongiorno and Carmelo Militello

Polymers 2024, 16(23), 3341; https://doi.org/10.3390/polym16233341 - 28 Nov 2024

Abstract

Within the range of composite laminates for structural applications, sandwich laminates are a special category intended for applications characterized by high flexural stresses. As it is well known from the technical literature, structural sandwich laminates have a simple configuration consisting of two skins of very strong material, to which the flexural strength is delegated, between which an inner layer (core) of light material with sufficient shear strength is interposed. As an example, a sandwich configuration widely used in civil, naval, and mechanical engineering is that obtained with fiberglass skins and a core of various materials, such as polyurethane foam or another lightweight material, depending on the application. Increasingly stringent regulations aimed at protecting the environment by reducing harmful emissions of carbon dioxide and carbon monoxide have directed recent research towards the development of new composites and new sandwiches characterized by low environmental impact. Among the various green composite solutions proposed in the literature, a very promising category is that of high-performance biocomposites, which use bio-based matrices reinforced by fiber reinforcements. This approach can also be used to develop green sandwiches for structural applications, consisting of biocomposite skins and cores made by low-environmental impact or renewable materials. In order to make a contribution to this field, a structural sandwich consisting of high-performance sisal–epoxy biocomposite skins and an innovative renewable core made of balsa wood laminates with appropriate lay-ups has been developed and then properly characterized in this work. Through a systematic theoretical–experimental analysis of three distinct core configurations, the unidirectional natural core, the cross-ply type, and the angle-ply type, it has been shown how the use of natural balsa gives rise to inefficient sandwiches, whereas performance optimization is fully achieved by considering the angle-ply core type [±45/90]. Finally, the subsequent comparison with literature data of similar sandwiches has shown how the optimal configuration proposed can be advantageously used to replace synthetic glass–resin sandwiches widely used in various industrial sectors (mechanical engineering, shipbuilding, etc.) and in civil engineering. Full article

(This article belongs to the Section Polymer Fibers)

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Abstract

This study investigates the biosorption capabilities of kefir grains, a polysaccharide-based byproduct of the fermentation process, for removing copper(II) and arsenic(V) from contaminated water. Unlike traditional heavy-metal removal methods, which are typically expensive and involve environmentally harmful chemicals, biopolymeric materials such as kefir grains provide a sustainable and cost-effective alternative for adsorbing hazardous inorganic pollutants from aqueous solutions. Our experimental results revealed significant differences in the sorption capacities of two types of kefir grains. Grains of milk kefir outperformed water kefir, particularly in copper(II) removal, achieving up to 95% efficiency at low copper concentrations (0.16 mmol·L⁻¹) and demonstrating a maximum sorption capacity of 49 µmol·g⁻¹. In contrast, water kefir grains achieved only 35.5% maximum removal efficiency and exhibited lower sorption capacity. For arsenic(V) removal, milk kefir grains also showed superior performance, removing up to 56% of arsenic in diluted solution with experimental sorption capacities reaching up to 20 µmol·g⁻¹, whereas water kefir grains achieved a maximum removal efficiency of 34.5%. However, these findings also suggest that while kefir grains show potential as low-cost biosorbents, further modifications are needed to enhance their competitiveness for large-scale water treatment applications. Full article

22 pages, 8194 KiB

Open AccessArticle

Additively Manufactured Carbon Fibre PETG Composites: Effect of Print Parameters on Mechanical Properties

by Andreas L. Economides, Md Niamul Islam and Konstantinos P. Baxevanakis

Polymers 2024, 16(23), 3336; https://doi.org/10.3390/polym16233336 - 28 Nov 2024

Abstract

This study investigates the quasi-static and viscoelastic properties of additively manufactured (AM) PETG reinforced with short carbon fibres. Samples were manufactured using different parameters in terms of the infill pattern, porosity, and annealing condition. Tensile and compressive tests were conducted to determine quasi-static properties such as Young’s modulus and toughness, and dynamic mechanical analysis was used under a frequency sweep of 1–100 Hz to describe the viscoelastic behaviour of the composites. The major impacts and responses between the print parameters were quantified using Analyses of Variance (ANOVAs), which revealed the major contributor to each mechanical property. Fractography on the tensile samples using scanning electron microscopy demonstrated fibre pull-out, indicating poor fibre–matrix bonding, but also revealed interfacial bonding between raster lines in the annealed samples. This had a prominent effect on the properties of latitudinal samples where the force applied was perpendicular to the raster lines. Generally, porosity appeared to have the greatest contribution to the variance in the mechanical properties, with the exception of the tensile modulus, where the infill pattern had a more substantial effect. Annealing caused a consistent increase in the tensile modulus of the tested samples, which can be used to support the design and optimisation of AM parts when they are used under specific loading conditions. Full article

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

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