Next Issue
Volume 16, September-1
Previous Issue
Volume 16, August-1
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
8.0
4.7
Journals
Polymers
Volume 16
Issue 16
polymers-logo

Journal Menu

► Journal Menu

Journal Browser

► Journal Browser
share announcement

Polymers, Volume 16, Issue 16 (August-2 2024) – 155 articles

Cover Story (view full-size image): Vinyl-addition polynorbornenes are candidates for designing high-performance polymers due to their unique characteristics. However, synthesis with different catalysts results in materials with distinct properties, potentially due to the presence of various stereoisomers. Herein, we develop all-atom models of polynorbornene oligomers based on classical force fields and density functional theory. We perform detailed molecular dynamics simulations and propose simpler coarse-grained models to address the high molecular weight limit. In the melt state, meso chains form highly rigid extended coils with amorphous structural characteristics. In contrast, simulations with racemo chains predict highly helical tubular chain conformations that could assemble into crystalline structures. View this paper

Vinyl-addition polynorbornenes are candidates for designing high-performance polymers due to their unique characteristics. However, synthesis with different catalysts results in materials with distinct properties, potentially due to the presence of various stereoisomers. Herein, we develop all-atom models of polynorbornene oligomers based on classical force fields and density functional theory. We perform detailed molecular dynamics simulations and propose simpler coarse-grained models to address the high molecular weight limit. In the melt state, meso chains form highly rigid extended coils with amorphous structural characteristics. In contrast, simulations with racemo chains predict highly helical tubular chain conformations that could assemble into crystalline structures.

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
10 pages, 3561 KiB  
Article
Effect of the Addition of PLA on the Thermal and Mechanical Properties of Reprocessed HDPE
by Anayansi Estrada-Monje, Miroslava Alejandra Silva-Goujon, Isis Rodríguez-Sánchez, Alain Salvador Conejo-Dávila, Claudia Ivone Piñón-Balderrama, Anayansi Zaragoza-Estrada, Leonardo Aurelio Baldenegro-Pérez and Erasto Armando Zaragoza-Contreras
Polymers 2024, 16(16), 2387; https://doi.org/10.3390/polym16162387 - 22 Aug 2024
Viewed by 518
Abstract
Amid the current environmental crisis caused by plastic accumulation, one of the proposed solutions to manage this problem is using biodegradable polymers. However, the impact of adding biodegradable polymers to the well-established circular economy of recyclable polymers, such as HDPE, has not been [...] Read more.
Amid the current environmental crisis caused by plastic accumulation, one of the proposed solutions to manage this problem is using biodegradable polymers. However, the impact of adding biodegradable polymers to the well-established circular economy of recyclable polymers, such as HDPE, has not been fully considered. Therefore, there is a need to reconsider the way we consume, dispose of, and manage biodegradable polymers after use. This study evaluates the effect of varying the contents of a biodegradable polymer, taking poly(lactic acid) (PLA) as a model biodegradable polymer, on the thermal and mechanical properties of HDPE. The study highlights the importance of identifying and disposing of biodegradable polymers to avoid mixtures with HDPE, in order not to affect mechanical performance when considering reprocessing and a new life cycle of this conventional polymer. Full article
(This article belongs to the Special Issue Advanced Polymer Blends: From Processing to Characterisation and Application)
►▼ Show Figures

Figure 1

24 pages, 4857 KiB  
Review
Rheological Characteristics of Hyaluronic Acid Fillers as Viscoelastic Substances
by Gi-Woong Hong, Jovian Wan, Youngjin Park, Kathleen Chang, Lisa Kwin Wah Chan, Kar Wai Alvin Lee and Kyu-Ho Yi
Polymers 2024, 16(16), 2386; https://doi.org/10.3390/polym16162386 - 22 Aug 2024
Viewed by 530
Abstract
Hyaluronic acid (HA) fillers are widely used in esthetic medicine and are categorized into biphasic and monophasic types based on their manufacturing processes. To evaluate the quality of these fillers, it is essential to understand their rheological properties, which reflect their viscoelastic nature. [...] Read more.
Hyaluronic acid (HA) fillers are widely used in esthetic medicine and are categorized into biphasic and monophasic types based on their manufacturing processes. To evaluate the quality of these fillers, it is essential to understand their rheological properties, which reflect their viscoelastic nature. Rheology, the study of material deformation and flow, reveals how fillers behave under stress, combining properties of solids and liquids. This study explores the fundamental principles of elasticity and viscosity, rooted in Hooke’s law of elasticity and Newton’s law of viscosity, to explain the complex behavior of viscoelastic substances like HA fillers. The distinction between biphasic and monophasic fillers lies in their chemical cross-linking processes, which impact their molecular weight, structure, and ultimately, their clinical performance. Biphasic fillers with minimal cross-linking rely on natural molecular entanglements, exhibiting lower modification efficiency and greater elasticity. Conversely, monophasic fillers, which undergo extensive chemical cross-linking, demonstrate higher modification efficiency, firmer texture, and enhanced resistance to enzymatic degradation. The study emphasizes the importance of thoroughly removing residual cross-linking agents to ensure filler safety. Understanding these rheological characteristics aids clinicians in selecting appropriate fillers based on injection sites, tissue conditions, and desired outcomes, balancing viscoelastic properties and safety for optimal esthetic results. Full article
(This article belongs to the Special Issue Polymeric Materials for Drug Delivery and Tissue Engineering Applications)
►▼ Show Figures

Figure 1

14 pages, 2626 KiB  
Article
Development of Advanced Solid-State Thermochromic Materials for Responsive Smart Window Applications
by Kai Zeng, Chang Xue, Jinbo Wu and Weijia Wen
Polymers 2024, 16(16), 2385; https://doi.org/10.3390/polym16162385 - 22 Aug 2024
Viewed by 531
Abstract
This study introduces the synthesis and detailed characterization of a novel thermochromic material capable of reversible alterations in its thermotropic transmittance. Through an emulsion polymerization process, this newly developed material is composed of 75–85% octadecyl acrylate and 0–7% allyl methacrylate, demonstrating a pronounced [...] Read more.
This study introduces the synthesis and detailed characterization of a novel thermochromic material capable of reversible alterations in its thermotropic transmittance. Through an emulsion polymerization process, this newly developed material is composed of 75–85% octadecyl acrylate and 0–7% allyl methacrylate, demonstrating a pronounced discoloration effect across a narrow yet critical temperature range of 24.5–39 °C. The synthesized powder underwent a battery of tests, including differential scanning calorimetry and thermogravimetric analysis, as well as scanning electron microscopy. These comprehensive evaluations confirmed the material’s exceptional thermal stability, uniform particle size distribution, and strong anchoring properties. Building upon these findings, we advanced the development of thermochromic polyvinyl butyral films and laminated glass products. By utilizing a coextrusion technique, we integrated these films into laminated glass, setting a new benchmark against existing glass technologies. Remarkably, the incorporation of thermochromic PVB films into laminated glass led to a significant reduction in solar irradiance of 20–30%, outperforming traditional double silver low-emissivity glass. This achievement demonstrates the exceptional shading and thermal insulation properties of the material. The research presented herein not only pioneers a valuable methodology for the engineering of smart materials with tunable thermotropic transmittance but also holds the key to unlocking enhanced energy efficiency across a spectrum of applications. The potential impact of this innovation on the realm of sustainable building materials is profound, promising significant strides toward energy conservation and environmental stewardship. Full article
(This article belongs to the Special Issue Advanced Stimuli-Responsive Polymer Composites)
►▼ Show Figures

Figure 1

21 pages, 2793 KiB  
Article
The Optimization of Avocado-Seed-Starch-Based Degradable Plastic Synthesis with a Polylactic Acid (PLA) Blend Using Response Surface Methodology (RSM)
by Rozanna Dewi, Novi Sylvia, Zulnazri Zulnazri, Herman Fithra, Medyan Riza, Januar Parlaungan Siregar, Tezara Cionita, Deni Fajar Fitriyana and Samsudin Anis
Polymers 2024, 16(16), 2384; https://doi.org/10.3390/polym16162384 - 22 Aug 2024
Viewed by 506
Abstract
This research improves the strength of plastic using avocado seed starch and PLA. The effect of blending avocado seed starch and PLA was optimized using the RSM approach by using two variables: water absorption and biodegradability. Mixing them using RSM gave the best [...] Read more.
This research improves the strength of plastic using avocado seed starch and PLA. The effect of blending avocado seed starch and PLA was optimized using the RSM approach by using two variables: water absorption and biodegradability. Mixing them using RSM gave the best result: 1.8 g of starch and 3 g of PLA. Degradable plastic has a tensile strength of 10.1 MPa, elongation at a break of 85.8%, and a Young’s modulus of 190 MPa. Infrared spectroscopy showed that the plastic had a -OH bond at 3273.20 cm−1, 3502.73 cm−1, and 3647.39 cm−1, a CH2 bond at 2953.52 cm−1, 2945.30 cm−1, and 2902.87 cm−1, a C=C bond at 1631.78 cm−1, and a C-O bond at 1741.72 cm−1. The plastic decomposed in the soil. It was organic and hydrophilic. Thermal tests demonstrated that the plastic can withstand heat well, losing weight at 356.86 °C to 413.64 °C, forming crystals and plastic melts at 159.10 °C—the same as PLA. In the melt flow test, the sample melted before measurement, and was therefore not measurable—process conditions affected it. A water absorption of 5.763% and biodegradation rate of 37.988% were found when the samples were decomposed for 12 days. The starch and PLA fused in the morphology analysis to form a smooth surface. The RSM value was close to 1. The RSM gave the best process parameters. Full article
(This article belongs to the Special Issue Advanced Biopolymers and Biocomposites)
►▼ Show Figures

Figure 1

15 pages, 2724 KiB  
Article
Fracture Analysis of Highly Flexible Adhesives: Cohesive Zone Modelling across a Wide Spectrum of Temperatures and Strain Rates
by Tomas Nunes, Maria J. P. Ribas, Alireza Akhavan-Safar, Ricardo J. C. Carbas, Eduardo A. S. Marques, Sabine Wenig and Lucas F. M. da Silva
Polymers 2024, 16(16), 2383; https://doi.org/10.3390/polym16162383 - 22 Aug 2024
Viewed by 449
Abstract
This study focuses on the prediction of the fracture mechanics behaviour of a highly flexible adhesive (with a tensile elongation of 90%), since this type of adhesive is becoming widely used in automotive structures due to their high elongation at break and damping [...] Read more.
This study focuses on the prediction of the fracture mechanics behaviour of a highly flexible adhesive (with a tensile elongation of 90%), since this type of adhesive is becoming widely used in automotive structures due to their high elongation at break and damping capacity. Despite their extensive applications, the understanding of their fracture mechanics behaviour under varying loading rates and temperatures remains limited in the literature. In addition, current prediction models are also unable to accurately predict their behaviour due to the complex failure mechanism that such bonded joints have. This study aims to determine whether a simple triangular cohesive zone model (CZM), which predefines the crack path, can reproduce the load–displacement curves of adhesives under various temperatures and strain rates. To achieve this, a calibrated CZM is used, adapting the model for reference joints and then validating it with independent test results conducted in a wide range of loading and environmental conditions. The tests were performed at speeds between 0.2 and 6000 mm/min and at three different temperatures ranging from −30 °C to 60 °C. Mode I fracture toughness was measured using the DCB (double cantilever beam) specimens. Using a simple triangular CZM may not be optimal for predicting the mechanical response of highly flexible adhesives with complex failure mechanisms and multiple crack paths. However, by correctly adjusting the cohesive zone properties for a limited set of reference conditions, it is possible to accurately predict the mechanical response of these joints across various test speeds and temperatures, significantly reducing costs and effort. Full article
(This article belongs to the Section Polymer Processing and Engineering)
►▼ Show Figures

Figure 1

18 pages, 7291 KiB  
Article
Functionalized Triblock Copolymers with Tapered Design for Anion Exchange Membrane Fuel Cells
by Ming-Tsung Lee
Polymers 2024, 16(16), 2382; https://doi.org/10.3390/polym16162382 - 22 Aug 2024
Viewed by 467
Abstract
Triblock copolymers such as styrene-b-(ethylene-co-butylene)-b-styrene (SEBS) have been widely used as an anion exchange membrane for fuel cells due to their phase separation properties. However, modifying the polymer architecture for optimized membrane properties is still challenging. This research develops a strategy to control [...] Read more.
Triblock copolymers such as styrene-b-(ethylene-co-butylene)-b-styrene (SEBS) have been widely used as an anion exchange membrane for fuel cells due to their phase separation properties. However, modifying the polymer architecture for optimized membrane properties is still challenging. This research develops a strategy to control the membrane morphology based on quaternized SEBS (SEBS-Q) by dual-tapering the interfacial block sequences. The structural and transport properties of SEBS-Q with various tapering styles at different hydration levels are systematically investigated by coarse-grained molecular simulations. The results show that the introduction of the tapered regions induces the formation of a bicontinuous water domain and promotes the diffusivity of the mobile components. The interplay between the solvation of the quaternary groups and the tapered fraction determines the conformation of polymer chains among the hydrophobic–hydrophilic subdomains. The strategy presented here provides a new path to fabricating fuel cell membranes with controlled microstructures. Full article
(This article belongs to the Special Issue Advances in Polymer-Based Materials for Energy Applications)
►▼ Show Figures

Figure 1

10 pages, 10070 KiB  
Communication
Properties of EPDM Nanocomposites Reinforced with Modified Montmorillonite
by Zhanxu Li, Zilong Chen, Weichong Sun, Yangling Liu, Xiong Wang, Jun Lin, Jian Wang and Shaojian He
Polymers 2024, 16(16), 2381; https://doi.org/10.3390/polym16162381 - 22 Aug 2024
Viewed by 402
Abstract
Considering the dilemma of obtaining economic and high-performance composites based on non-polar and main-chain-saturated ethylene propylene diene monomer rubber (EPDM), we proposed an effective and universal filler modification and nanocomposite preparation method. Specifically, the montmorillonite (MMT) surface was coated with polydopamine (PDA) to [...] Read more.
Considering the dilemma of obtaining economic and high-performance composites based on non-polar and main-chain-saturated ethylene propylene diene monomer rubber (EPDM), we proposed an effective and universal filler modification and nanocomposite preparation method. Specifically, the montmorillonite (MMT) surface was coated with polydopamine (PDA) to obtain DMMT, which was confirmed by XRD, XPS, FTIR, and TGA. After compounding DMMT gel with the solid EPDM via the gel compounding method, a silane coupling agent, vinyltrimethoxysilane, was introduced to construct covalent interactions between rubber and filler. Compared with the unmodified MMT filler EPDM, the EPDM/DMMT nanocomposite showed much fewer filler aggregates in the matrix. The highest tensile strength of the composites reached 6.5 MPa with 10 phr DMMT, almost 200% higher than that of pure EPDM. Full article
(This article belongs to the Special Issue Advances in Functional Polymers and Composites)
►▼ Show Figures

Graphical abstract

13 pages, 3648 KiB  
Article
Enhancing Selectivity with Molecularly Imprinted Polymers via Non-Thermal Dielectric Barrier Discharge Plasma
by Samira Amiri Khoshkar Vandani, Qianwei Liu, Yuki Lam and Hai-Feng Ji
Polymers 2024, 16(16), 2380; https://doi.org/10.3390/polym16162380 - 22 Aug 2024
Viewed by 438
Abstract
Molecularly imprinted polymers (MIPs) are synthetic polymers that mimic the functions of antibodies. Though MIPs are promising tools in various areas, achieving high selectivity in MIPs can be difficult. To improve selectivity, various approaches have been implemented; however, the role of polymerization methods [...] Read more.
Molecularly imprinted polymers (MIPs) are synthetic polymers that mimic the functions of antibodies. Though MIPs are promising tools in various areas, achieving high selectivity in MIPs can be difficult. To improve selectivity, various approaches have been implemented; however, the role of polymerization methods or synthetic techniques in enhancing the selectivity of MIPs has not been studied and remains a crucial area for further research. MIPs are typically prepared from free radical reactions. Recently, we found that Dielectric Barrier Discharge (DBD) plasma can be used to initiate the polymerization of vinyl monomers. The DBD plasma method allows the monomers to associate with the template molecules and initiate polymerization with minimal disruption to the positioning of the monomers. We hypothesize that this could be a preferred method to prepare MIPs over the traditional radical reaction that may cause a disturbance of the pre-associated monomers on the templates for the polymerization. Chicken egg white serum albumin (CESA) was used as the template protein for the MIPs. Our results show that in all test conditions, approximately twofold improvement in selectivity was achieved, which is the primary performance metric for MIPs. This enhancement was evident across all categories, including MIPs prepared from various monomer combinations. Full article
(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials: 2nd Edition)
►▼ Show Figures

Figure 1

14 pages, 6036 KiB  
Review
Constructing Multifunctional Composite Single Crystals via Polymer Gel Incorporation
by Zhiwen Mao, Jie Ren and Hanying Li
Polymers 2024, 16(16), 2379; https://doi.org/10.3390/polym16162379 - 22 Aug 2024
Viewed by 394
Abstract
The non-uniformity of a single crystal can sometimes be found in biominerals, where surrounding biomacromolecules are incorporated into the growing crystals. This unique composite structure, combining heterogeneity and long-range ordering, enables the functionalization of single crystals. Polymer gel media are often used to [...] Read more.
The non-uniformity of a single crystal can sometimes be found in biominerals, where surrounding biomacromolecules are incorporated into the growing crystals. This unique composite structure, combining heterogeneity and long-range ordering, enables the functionalization of single crystals. Polymer gel media are often used to prepare composite single crystals, in which the growing crystals incorporate gel networks and form a bi-continuous interpenetrating structure without any disruption to single crystallinity. Moreover, dyes and many kinds of nanoparticles can be occluded into single crystals under the guidance of gel incorporation. On this basis, the bio-inspired method has been applied in crystal morphology control, crystal dyeing, mechanical reinforcement, and organic bulk heterojunction-based optoelectronics. In this paper, the composite structure, the incorporation mechanisms, and the multiple functions of gel-incorporated single crystals are reviewed. Full article
(This article belongs to the Special Issue Advances in Polymers Science and Technology: From Nano-Engineering to Multifunctional Applications)
►▼ Show Figures

Figure 1

16 pages, 2836 KiB  
Article
Does the Addition of Low-Dose Antibiotics Compromise the Mechanical Properties of Polymethylmethacrylate (PMMA)?
by Valentina Egger, Dietmar Dammerer, Gerald Degenhart, Johannes D. Pallua, Werner Schmölz, Martin Thaler, Klaus-Dieter Kühn, Michael Nogler and David Putzer
Polymers 2024, 16(16), 2378; https://doi.org/10.3390/polym16162378 - 22 Aug 2024
Viewed by 375
Abstract
The increasing numbers of total joint replacements and related implant-associated infections demand solutions, which can provide a high-dose local delivery of antibiotics. Antibiotic-loaded bone cement (ALBC) is an accepted treatment method for infected joint arthroplasties. The mechanical properties of low-dose gentamicin-loaded bone cement [...] Read more.
The increasing numbers of total joint replacements and related implant-associated infections demand solutions, which can provide a high-dose local delivery of antibiotics. Antibiotic-loaded bone cement (ALBC) is an accepted treatment method for infected joint arthroplasties. The mechanical properties of low-dose gentamicin-loaded bone cement (BC) in medium- and high-viscosity versions were compared to unloaded BC using a vacuum mixing system. As an additional control group, manual mixed unloaded BC was used. In a uniaxial compression test, ultimate compressive strength, compressive yield strength, and compression modulus of elasticity, as well as ultimate and yield strain, were determined according to ISO 5833-2022 guidelines. All groups exceeded the minimum compressive strength (70 MPa) specified in the ISO 5833 guidelines. Both ALBC groups showed a similar ultimate compressive and yield strength to the unloaded BC. The results showed that vacuum mixing increased the compression strength of BC. ALBC showed similar compressive strength to their non-antibiotic counterparts when vacuum mixing was performed. Added low-dose gentamicin acted as a plasticizer on bone cement. From a biomechanical point of view, the usage of gentamicin-based ALBC formulations is viable. Full article
(This article belongs to the Special Issue Physicochemical Properties of Polymer Composites)
►▼ Show Figures

Figure 1

20 pages, 11485 KiB  
Article
Fabrication and Characterization of Dissolving Microneedles Containing Oryza sativa L. Extract Complex for Enhancement of Transfollicular Delivery
by Tanpong Chaiwarit, Baramee Chanabodeechalermrung, Pensak Jantrawut, Warintorn Ruksiriwanich and Mathukorn Sainakham
Polymers 2024, 16(16), 2377; https://doi.org/10.3390/polym16162377 - 22 Aug 2024
Viewed by 459
Abstract
Dissolving microneedles are extensively applied in drug delivery systems to enhance penetration into the skin. In this study, dissolving microneedles fabricated from polyvinylpyrrolidone K90 (PVP-K90) and hydroxypropylmethyl cellulose (HPMC) E50 in different ratios were characterized. The selected formulations incorporated Oryza sativa L. extract [...] Read more.
Dissolving microneedles are extensively applied in drug delivery systems to enhance penetration into the skin. In this study, dissolving microneedles fabricated from polyvinylpyrrolidone K90 (PVP-K90) and hydroxypropylmethyl cellulose (HPMC) E50 in different ratios were characterized. The selected formulations incorporated Oryza sativa L. extract complex and its characteristics, transfollicular penetration, and safety were observed. The microneedles, fabricated from PVP K90: HPMC E50 in a ratio of 25:5 (P25H5) and 20:10 (P20H10), revealed excellent morphological structure, proper mechanical strength, and excellent skin insertion. P25H5 microneedles exhibited faster dissolution than P20H10 microneedles. Microneedles containing Oryza sativa L. extract complex showed excellent morphological structure via scanning electron microscopy but decreased mechanical strength. P25H5-O, which exhibited an effective ability to enter skin, was selected for further investigation. This microneedle formulation had a high percentage of drug-loading content, enhanced skin penetration via the transfollicular route, and was safe for keratinocytes. As a result, the dissolving microneedle containing Oryza sativa L. extract complex can be used to enhance transfollicular delivery through the skin with safety. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
►▼ Show Figures

Figure 1

15 pages, 4010 KiB  
Article
Synthesis of High-Molecular-Weight Polypropylene Elastomer by Propylene Polymerization Using α-Diimine Nickel Catalysts
by Lujie Gao, Hegang Ren, Yanhui Hou, Linlin Ye, Hao Meng, Binyuan Liu and Min Yang
Polymers 2024, 16(16), 2376; https://doi.org/10.3390/polym16162376 - 22 Aug 2024
Viewed by 492
Abstract
The α-diimine late transition metal catalyst represents a new strategy for the synthesis of atactic polypropylene elastomer. Taking into account the properties of the material, enhancing the molecular weight of polypropylene at an elevated temperature through modifying the catalyst structure, and further increasing [...] Read more.
The α-diimine late transition metal catalyst represents a new strategy for the synthesis of atactic polypropylene elastomer. Taking into account the properties of the material, enhancing the molecular weight of polypropylene at an elevated temperature through modifying the catalyst structure, and further increasing the activity of α-diimine catalyst for propylene polymerization, are urgent problems to be solved. In this work, two α-diimine nickel(II) catalysts with multiple hydroxymethyl phenyl substituents were synthesized and used for propylene homopolymerization. The maximum catalytic activity was 5.40 × 105 gPP/molNi·h, and the activity was still maintained above 105 gPP/molNi·h at 50 °C. The large steric hindrance of catalysts inhibited the chain-walking and chain-transfer reactions, resulting in polypropylene with high molecular weights (407~1101 kg/mol) and low 1,3-enchainment content (3.57~16.96%) in toluene. The low tensile strength (0.3~1.0 MPa), high elongation at break (218~403%) and strain recovery properties (S.R. ~50%, 10 tension cycles) of the resulting polypropylenes, as well as the visible light transmittance of approximately 90%, indicate the characteristics of the transparent elastomer. Full article
(This article belongs to the Special Issue Polyolefin: Synthesis, Properties, and Characterization)
►▼ Show Figures

Graphical abstract

20 pages, 4725 KiB  
Article
A Light-Powered Self-Circling Slider on an Elliptical Track with a Liquid Crystal Elastomer Fiber
by Lu Wei, Yanan Chen, Junjie Hu, Xueao Hu, Jiale Wang and Kai Li
Polymers 2024, 16(16), 2375; https://doi.org/10.3390/polym16162375 - 22 Aug 2024
Viewed by 500
Abstract
In this paper, we propose an innovative light-powered LCE-slider system that enables continuous self-circling on an elliptical track and is comprised of a light-powered LCE string, slider, and rigid elliptical track. By formulating and solving dimensionless dynamic equations, we explain static and self-circling [...] Read more.
In this paper, we propose an innovative light-powered LCE-slider system that enables continuous self-circling on an elliptical track and is comprised of a light-powered LCE string, slider, and rigid elliptical track. By formulating and solving dimensionless dynamic equations, we explain static and self-circling states, emphasizing self-circling dynamics and energy balance. Quantitative analysis reveals that the self-circling frequency of LCE-slider systems is independent of the initial tangential velocity but sensitive to light intensity, contraction coefficients, elastic coefficients, the elliptical axis ratio, and damping coefficients. Notably, elliptical motion outperforms circular motion in angular velocity and frequency, indicating greater efficiency. Reliable self-circling under constant light suggests applications in periodic motion fields, especially celestial mechanics. Additionally, the system’s remarkable adaptability to a wide range of curved trajectories exemplifies its flexibility and versatility, while its energy absorption and conversion capabilities position it as a highly potential candidate for applications in robotics, construction, and transportation. Full article
(This article belongs to the Special Issue Polymer Materials for Sensors and Actuators)
►▼ Show Figures

Figure 1

17 pages, 9630 KiB  
Article
Evaluation of Fatigue Damage Monitoring of Single-Lap Composite Adhesive Joint Using Conductivity
by Chow-Shing Shin and Shun-Hsuan Huang
Polymers 2024, 16(16), 2374; https://doi.org/10.3390/polym16162374 - 22 Aug 2024
Viewed by 546
Abstract
The widely used adhesive joining technique suffers from the drawback of being unable to be dismantled to examine for degradation. To counteract this weakness, several structural health monitoring (SHM) methods have been proposed to reveal the joint integrity status. Among these, doping the [...] Read more.
The widely used adhesive joining technique suffers from the drawback of being unable to be dismantled to examine for degradation. To counteract this weakness, several structural health monitoring (SHM) methods have been proposed to reveal the joint integrity status. Among these, doping the adhesive with carbon nanotubes to make the joint conductive and monitoring its electrical resistance change is a promising candidate as it is of relatively low cost and easy to implement. In this work, resistance change to monitor fatigue debonding of composite single-lap adhesive joints has been attempted. The debonded area, recorded with a liquid penetrant technique, related linearly to the fatigue life expended. However, it correlates with the resistance change in two different trends. Scanning electron microscopy on the fracture surface reveals that the two trends are associated with distinct failure micromechanisms. Implications of these observations on the practical use of the resistance change for SHM are discussed. Full article
(This article belongs to the Special Issue Damage and Failure Analysis of Polymer-Based Composites)
►▼ Show Figures

Graphical abstract

22 pages, 5095 KiB  
Article
Development of Interpolyelectrolyte Complex Based on Chitosan and Carboxymethylcellulose for Stabilizing Sandy Soil and Stimulating Vegetation of Scots Pine (Pinus sylvestris L.)
by Nazira Berikbol, Alexey Klivenko, Vadim Markin, Lazzyat Orazzhanova, Gulnur Yelemessova and Zhanar Kassymova
Polymers 2024, 16(16), 2373; https://doi.org/10.3390/polym16162373 - 22 Aug 2024
Viewed by 647
Abstract
The issue of water and wind erosion of soil remains critically important. Polymeric materials offer a promising solution to this problem. In this study, we prepared and applied an interpolyelectrolyte complex (IPEC) composed of the biopolymers chitosan and sodium carboxymethyl cellulose (Na-CMC) for [...] Read more.
The issue of water and wind erosion of soil remains critically important. Polymeric materials offer a promising solution to this problem. In this study, we prepared and applied an interpolyelectrolyte complex (IPEC) composed of the biopolymers chitosan and sodium carboxymethyl cellulose (Na-CMC) for the structuring of forest sandy soils and the enhancement of the pre-sowing treatment of Scots pine (Pinus sylvestris L.) seeds. A nonstoichiometric IPEC [Chitosan]:[Na-CMC] = [3:7] was synthesized, and its composition was determined using gravimetry, turbidimetry, and rheoviscosimetry methods. Soil surface treatment with IPEC involved the sequential application of a chitosan polycation (0.006% w/w) and Na-CMC polyanion (0.02% w/w) relative to the air-dry soil weight. The prepared IPEC increased soil moisture by 77%, extended water retention time by sixfold, doubled the content of agronomically valuable soil fractions > 0.25 mm, enhanced soil resistance to water erosion by 64% and wind erosion by 81%, and improved the mechanical strength of the soil-polymer crust by 17.5 times. Additionally, IPEC application resulted in slight increases in the content of humus, mobile potassium, mobile phosphorus, ammonium nitrogen, and mineral salts in the soil while maintaining soil solution pH stability and significantly increasing nitrate nitrogen levels. The novel application technologies of biopolymers and IPEC led to a 16–25% improvement in Scots pine seed germination and seedling growth metrics. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
►▼ Show Figures

Figure 1

1 pages, 133 KiB  
Correction
Correction: Badaraev et al. Surface Modification of Electrospun Bioresorbable and Biostable Scaffolds by Pulsed DC Magnetron Sputtering of Titanium for Gingival Tissue Regeneration. Polymers 2022, 14, 4922
by Arsalan D. Badaraev, Dmitrii V. Sidelev, Anna I. Kozelskaya, Evgeny N. Bolbasov, Tuan-Hoang Tran, Alexey V. Nashchekin, Aleksandra S. Kostina, Anna B. Malashicheva, Sven Rutkowski and Sergei I. Tverdokhlebov
Polymers 2024, 16(16), 2372; https://doi.org/10.3390/polym16162372 - 22 Aug 2024
Viewed by 451
Abstract
Aleksandra S [...] Full article
10 pages, 3410 KiB  
Communication
Expanding the Spectral Responsivity of Photodetectors via the Integration of CdSe/ZnS Quantum Dots and MEH−PPV Polymer Composite
by Thanh Thao Tran, Ha Trang Nguyen, Ankush Sharma, Young-Bin Cho, Manjeet Kumar and Ju-Hyung Yun
Polymers 2024, 16(16), 2371; https://doi.org/10.3390/polym16162371 - 21 Aug 2024
Viewed by 542
Abstract
This study investigates the energy transfer mechanism between the organic polymer poly(2-methoxy-5(2’-ethyl)heroxyphenylenevinylene) (MEH−PPV) and CdSe/ZnS core-shell quantum dots (CdSe/ZnS CSQDs). Additionally, a hybrid ZnO-based photodetector (PD) is fabricated using the composite of MEH−PPV and CdSe/ZnS CSQDs, aiming to gain deeper insights. The combination [...] Read more.
This study investigates the energy transfer mechanism between the organic polymer poly(2-methoxy-5(2’-ethyl)heroxyphenylenevinylene) (MEH−PPV) and CdSe/ZnS core-shell quantum dots (CdSe/ZnS CSQDs). Additionally, a hybrid ZnO-based photodetector (PD) is fabricated using the composite of MEH−PPV and CdSe/ZnS CSQDs, aiming to gain deeper insights. The combination of MEH−PPV and CdSe/ZnS CSQDs facilitates a broad spectral response in PDs, spanning from the ultraviolet (UV) to the visible range. In particular, PDs with QDs in the composite demonstrate notably excellent photosensitivity to both ultraviolet (UV) light (365 nm) (~5 fold) and visible light (505 nm) (~3 fold). Full article
(This article belongs to the Special Issue Application of Polymer Materials in Optoelectronic Devices)
►▼ Show Figures

Graphical abstract

23 pages, 8116 KiB  
Article
Understanding the Effect of Drilling Parameters on Hole Quality of Fiber-Reinforced Polymer Structures
by Katarzyna Biruk-Urban, Paul Bere, Razvan Udroiu, Jerzy Józwik and Karolina Beer-Lech
Polymers 2024, 16(16), 2370; https://doi.org/10.3390/polym16162370 - 21 Aug 2024
Viewed by 450
Abstract
Hole quality in composite materials is gaining interest in aerospace, automotive, and marine industries, especially for structural applications. This paper aims to investigate the quality of holes performed without a backup plate, in thin plates of glass fiber-reinforced polymer (GFRP). The samples were [...] Read more.
Hole quality in composite materials is gaining interest in aerospace, automotive, and marine industries, especially for structural applications. This paper aims to investigate the quality of holes performed without a backup plate, in thin plates of glass fiber-reinforced polymer (GFRP). The samples were manufactured by two different technologies: vacuum bagging and an innovative method named vacuum mold pressing. Three experiments were designed choosing the control factors that affect the maximum cutting force, delamination factor, and surface roughness of drilled holes in composite materials based on twill fabric layers. Quality analysis of the hole features was performed by microscopy investigations. The effects of the main factors on the targets are investigated using the statistical design of experiments, considering control factors, such as support opening width, weight fraction (wf), feed per tooth, and hole area. The results showed that the feed per tooth and hole area had a more significant influence on the delamination factors and surface roughness (Sa). The best quality of the holes drilled in twill-based GFRP was achieved for a lower feed rate of 0.04 mm/tooth and used a support opening width of 55 mm. Full article
(This article belongs to the Section Polymer Processing and Engineering)
►▼ Show Figures

Figure 1

17 pages, 2636 KiB  
Article
Highly Sensitive and Flexible Capacitive Pressure Sensors Combined with Porous Structure and Hole Array Using Sacrificial Templates and Laser Ablation
by Yibin Zhao, Jingyu Zhou, Chenkai Jiang, Tianlong Xu, Kaixin Li, Dawei Zhang and Bin Sheng
Polymers 2024, 16(16), 2369; https://doi.org/10.3390/polym16162369 - 21 Aug 2024
Viewed by 616
Abstract
Flexible, wearable pressure sensors offer numerous benefits, including superior sensing capabilities, a lightweight and compact design, and exceptional conformal properties, making them highly sought after in various applications including medical monitoring, human–computer interactions, and electronic skins. Because of their excellent characteristics, such as [...] Read more.
Flexible, wearable pressure sensors offer numerous benefits, including superior sensing capabilities, a lightweight and compact design, and exceptional conformal properties, making them highly sought after in various applications including medical monitoring, human–computer interactions, and electronic skins. Because of their excellent characteristics, such as simple fabrication, low power consumption, and short response time, capacitive pressure sensors have received widespread attention. As a flexible polymer material, polydimethylsiloxane (PDMS) is widely used in the preparation of dielectric layers for capacitive pressure sensors. The Young’s modulus of the flexible polymer can be effectively decreased through the synergistic application of sacrificial template and laser ablation techniques, thereby improving the functionality of capacitive pressure sensors. In this study, a novel sensor was introduced. Its dielectric layer was developed through a series of processes, including the use of a sacrificial template method using NaCl microparticles and subsequent CO2 laser ablation. This porous PDMS dielectric layer, featuring an array of holes, was then sandwiched between two flexible electrodes to create a capacitive pressure sensor. The sensor demonstrates a sensitivity of 0.694 kPa−1 within the pressure range of 0–1 kPa and can effectively detect pressures ranging from 3 Pa to 200 kPa. The sensor demonstrates stability for up to 500 cycles, with a rapid response time of 96 ms and a recovery time of 118 ms, coupled with a low hysteresis of 6.8%. Furthermore, our testing indicates that the sensor possesses limitless potential for use in detecting human physiological activities and delivering signals. Full article
(This article belongs to the Special Issue Polymer-Based Flexible Materials, 2nd Edition)
►▼ Show Figures

Figure 1

27 pages, 14954 KiB  
Article
Oral Administration of Berberine Hydrochloride Based on Chitosan/Carboxymethyl-β-Cyclodextrin Hydrogel
by Bukatuka Futila Clemence, Lin Xiao and Guang Yang
Polymers 2024, 16(16), 2368; https://doi.org/10.3390/polym16162368 - 21 Aug 2024
Viewed by 474
Abstract
In this study, a novel oral formulation of berberine hydrochloride (BBH) hydrogel was successfully synthesized through physical cross-linking using chitosan (CS) and carboxymethyl-β-cyclodextrin (CMCD). The characterization results confirmed the successful synthesis of the CS/CMCD hydrogel and the subsequent loading of BBH into this [...] Read more.
In this study, a novel oral formulation of berberine hydrochloride (BBH) hydrogel was successfully synthesized through physical cross-linking using chitosan (CS) and carboxymethyl-β-cyclodextrin (CMCD). The characterization results confirmed the successful synthesis of the CS/CMCD hydrogel and the subsequent loading of BBH into this composite (CS/CMCD/BBH) was effectively accomplished. The BBH was used as a model drug and the resulting hydrogel demonstrated a sustained drug release profile. In addition to its improved solubility and sustained release characteristics, the hydrogel exhibited excellent antibacterial activity against common pathogens such as Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Candida albicans (C. albicans). Additionally, in vitro studies indicated that the hydrogel was not cytotoxic to NIH3T3 and HaCaT cells, suggesting its safety for biomedical applications. This lack of cytotoxic effects, combined with the mechanical strength, solubility improvements, and antibacterial properties of the hydrogel, positions the CS/CMCD/BBH hydrogel as a promising candidate for the effective oral delivery of BBH. By addressing the solubility and delivery challenges of BBH, this hydrogel offers a viable solution for the oral administration of BBH, with potential applications in various biomedical fields. Full article
(This article belongs to the Special Issue Biomedical Applications of Polymeric Materials II)
►▼ Show Figures

Graphical abstract

18 pages, 7284 KiB  
Article
Biocompatibility and Antibacterial Activity of Eugenol and Copaiba Essential Oil-Based Emulsions Loaded on Cotton Textile Materials
by Laura Chirilă, Miruna S. Stan, Ionela C. Voinea, Alina Popescu, Alexandra-Gabriela Ene, Maricel Danu, Constanța Ibănescu and Mihaela-Cristina Lite
Polymers 2024, 16(16), 2367; https://doi.org/10.3390/polym16162367 - 21 Aug 2024
Viewed by 453
Abstract
The present study was focused on the preparation, characterization and application onto cotton fabrics of different topical oil-in-water emulsions based on chitosan, eugenol and copaiba essential oil for potential topical applications. Different amounts of copaiba essential oil (oil phases) and eugenol were used, [...] Read more.
The present study was focused on the preparation, characterization and application onto cotton fabrics of different topical oil-in-water emulsions based on chitosan, eugenol and copaiba essential oil for potential topical applications. Different amounts of copaiba essential oil (oil phases) and eugenol were used, while the water phase consisted of hamamelis water. The designed formulations were evaluated via optical microscopy and rheological parameters assessment. The textile materials treated with the developed emulsions were analyzed in terms of antibacterial efficiency and in vitro and in vivo biocompatibility. The rheological measurements have shown that the emulsions’ stability was dependent on their viscosity and structure of the colloidal systems. The emulsions remained stable at temperatures equal to or below 35 °C, but an increase in temperature led to droplet flocculation and creaming. The emulsion-treated textiles exhibited antibacterial activity against Escherichia coli and Staphylococcus aureus, and in vivo biocompatibility on the skin of guinea pigs without sensitization effects. Our study revealed that eugenol and copaiba essential oil-based emulsions loaded on cotton textile materials could be promising candidates for developing skin-friendly textiles designed for different topical applications. Full article
(This article belongs to the Special Issue Polymer Materials for Drug Delivery and Tissue Engineering II)
►▼ Show Figures

Figure 1

14 pages, 2034 KiB  
Article
Fabrication of a Microfluidic-Based Device Coated with Polyelectrolyte-Capped Titanium Dioxide to Couple High-Performance Liquid Chromatography with Inductively Coupled Plasma Mass Spectrometry for Mercury Speciation
by Ji-Hao Chen, Yu-Ting Luo, Yi-An Su, Yan-Ren Ke, Ming-Jay Deng, Wei-Yu Chen, Cheng-Yu Wang, Jia-Lin Tsai, Cheng-Hsing Lin and Tsung-Ting Shih
Polymers 2024, 16(16), 2366; https://doi.org/10.3390/polym16162366 - 21 Aug 2024
Viewed by 458
Abstract
Mercury (Hg) is a toxic element which impacts on biological systems and ecosystems. Because the toxicity of Hg species is highly dependent on their concentration levels and chemical forms, the sensitive identification of the chemical forms of Hg—i.e., Hg speciation—is of major significance [...] Read more.
Mercury (Hg) is a toxic element which impacts on biological systems and ecosystems. Because the toxicity of Hg species is highly dependent on their concentration levels and chemical forms, the sensitive identification of the chemical forms of Hg—i.e., Hg speciation—is of major significance in providing meaningful information about the sources of Hg exposure. In this study, a microfluidic-based device made of high-clarity poly(methyl methacrylate) (PMMA) was fabricated. Then, titanium dioxide nanoparticles (nano-TiO2s) were attached to the treated channel’s interior with the aid of poly(diallyldimethylammonium chloride) (PDADMAC). After coupling the nano-TiO2-coated microfluidic-based photocatalyst-assisted reduction device (the nano-TiO2-coated microfluidic-based PCARD) with high-performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP-MS), a selective and sensitive, hyphenated system for Hg speciation was established. Validation procedures demonstrated that the method could be satisfactorily applied to the determination of mercury ions (Hg2+) and methylmercury ions (CH3Hg+) in both human urine and water samples. Remarkably, the zeta potential measured clearly indicated that the PDADMAC-capped nano-TiO2s with a predominance of positive charges indeed provided a steady force for firm attachment to the negatively charged device channel. The cause of the durability of the nano-TiO2-coated microfluidic-based PCARD was clarified thus. Full article
(This article belongs to the Special Issue Polymer Electrolyte: Recent Progress and Applications)
►▼ Show Figures

Figure 1

15 pages, 17629 KiB  
Article
Influence of Cross-Linkers on the Wash Resistance of Chitosan-Functionalized Polyester Fabrics
by Tanja Pušić, Tea Bušac and Julija Volmajer Valh
Polymers 2024, 16(16), 2365; https://doi.org/10.3390/polym16162365 - 21 Aug 2024
Viewed by 387
Abstract
This study investigates the wash resistance of polyester fabrics functionalized with chitosan, a biopolymer known for its biocompatibility, non-toxicity, biodegradability and environmentally friendly properties. The interaction of chitosan with synthetic polymers, such as polyester, often requires surface treatment due to the weak natural [...] Read more.
This study investigates the wash resistance of polyester fabrics functionalized with chitosan, a biopolymer known for its biocompatibility, non-toxicity, biodegradability and environmentally friendly properties. The interaction of chitosan with synthetic polymers, such as polyester, often requires surface treatment due to the weak natural affinity between the two materials. To improve the interaction and stability of chitosan on polyester, alkaline hydrolysis of the polyester fabric was used as a surface treatment method. The effectiveness of using cross-linking agents 1,2,3,4-butane tetracarboxylic acid (BTCA) and hydroxyethyl methacrylate (HEMA) in combination with ammonium persulphate (APS) to improve the stability of chitosan on polyester during washing was investigated. The wash resistance of polyester fabrics functionalized with chitosan was tested after 1, 5 and 10 washes with a standard ECE detergent. Staining tests were carried out to evaluate the retention of chitosan on the fabric. The results showed that polyester fabrics functionalized with chitosan without cross-linkers exhibited better wash resistance than the fabrics treated with crosslinkers. Full article
(This article belongs to the Special Issue Development and Application of Bio-Based Polymers)
►▼ Show Figures

Figure 1

20 pages, 4918 KiB  
Article
Influence of Extrusion Parameters on the Mechanical Properties of Slow Crystallizing Carbon Fiber-Reinforced PAEK in Large Format Additive Manufacturing
by Patrick Consul, Matthias Feuchtgruber, Bernhard Bauer and Klaus Drechsler
Polymers 2024, 16(16), 2364; https://doi.org/10.3390/polym16162364 - 21 Aug 2024
Viewed by 453
Abstract
Additive Manufacturing (AM) enables the automated production of complex geometries with low waste and lead time, notably through Material Extrusion (MEX). This study explores Large Format Additive Manufacturing (LFAM) with carbon fiber-reinforced polyaryletherketones (PAEK), particularly a slow crystallizing grade by Victrex. The research [...] Read more.
Additive Manufacturing (AM) enables the automated production of complex geometries with low waste and lead time, notably through Material Extrusion (MEX). This study explores Large Format Additive Manufacturing (LFAM) with carbon fiber-reinforced polyaryletherketones (PAEK), particularly a slow crystallizing grade by Victrex. The research investigates how extrusion parameters affect the mechanical properties of the printed parts. Key parameters include line width, layer height, layer time, and extrusion temperature, analyzed through a series of controlled experiments. Thermal history during printing, including cooling rates and substrate temperatures, was monitored using thermocouples and infrared cameras. The crystallization behavior of PAEK was replicated in a Differential Scanning Calorimetry (DSC) setup. Mechanical properties were evaluated using three-point bending tests to analyze the impact of thermal conditions at the deposition interface on interlayer bonding and overall part strength. The study suggests aggregated metrics, enthalpy deposition rate and shear rate under the nozzle, that should be maximized to enhance mechanical performance. The findings show that the common practice of setting fixed layer times falls short of ensuring repeatable part quality. Full article
(This article belongs to the Topic Advanced Composites Manufacturing and Plastics Processing)
►▼ Show Figures

Figure 1

13 pages, 18808 KiB  
Article
Effects of Ultrasonication in Water and Isopropyl Alcohol on High-Crystalline Cellulose: A Fourier Transform Infrared Spectrometry and X-ray Diffraction Investigation
by Răzvan Rotaru, Maria E. Fortună, Elena Ungureanu and Carmen O. Brezuleanu
Polymers 2024, 16(16), 2363; https://doi.org/10.3390/polym16162363 - 21 Aug 2024
Viewed by 394
Abstract
This paper investigates the effects of ultrasonication on cellulose microparticles in different conditions. FTIR (Fourier transformed infrared spectrometry) and XRD (X-ray diffraction) analyses were used to compare the changes in the cellulose microstructure caused by the following various ultrasonic treatment conditions: time, amplitude [...] Read more.
This paper investigates the effects of ultrasonication on cellulose microparticles in different conditions. FTIR (Fourier transformed infrared spectrometry) and XRD (X-ray diffraction) analyses were used to compare the changes in the cellulose microstructure caused by the following various ultrasonic treatment conditions: time, amplitude of generated ultrasound waves, output power converted into ultrasound, the liquid medium (water and isopropyl alcohol) used for ultrasonication, and the shape of the vessel used for sonication. The cumulative results lead to an increase in the crystalline region directly proportional to the condition of sonication. Also, the total crystallinity index varied from 1.39 (pristine cellulose) to 1.94 for sonication in alcohol to 0.56 for sonication in water. The crystallinity index varied from 67% (cellulose) to 77% for the sample with 15 min of sonication in isopropyl alcohol and 50.4% for the sample with 15 min of sonication in water. Full article
(This article belongs to the Special Issue Polysaccharides: Synthesis, Properties and Applications)
►▼ Show Figures

Figure 1

17 pages, 934 KiB  
Review
Wood Sponge for Oil–Water Separation
by Chang Zhang, Taoyang Cai, Shangjie Ge-Zhang, Pingxuan Mu, Yuwen Liu and Jingang Cui
Polymers 2024, 16(16), 2362; https://doi.org/10.3390/polym16162362 - 21 Aug 2024
Viewed by 485
Abstract
In addition to filtering some sediments, hydrophobic wood sponges can also absorb many organic solvents, particularly crude oil. The leakage of crude oil poses a serious threat to the marine ecosystem, and oil mixed with water also generates great danger for its use. [...] Read more.
In addition to filtering some sediments, hydrophobic wood sponges can also absorb many organic solvents, particularly crude oil. The leakage of crude oil poses a serious threat to the marine ecosystem, and oil mixed with water also generates great danger for its use. From the perspective of low cost and high performance, wood sponges exhibit great potential for dealing with crude oil pollution. Wood sponge is a renewable material. With a highly oriented layered structure and a highly compressible three-dimensional porous frame, wood sponges are extremely hydrophobic, making them ideal for oil–water separation. Currently, the most common approach for creating wood sponge is to first destroy the wood cell wall to obtain a porous-oriented layered structure and then enhance the oil–water separation ability via superhydrophobic treatment. Wood sponge prepared using various experimental methods and different natural woods exhibits distinctive properties in regards to robustness, compressibility, fatigue resistance, and oil absorption ability. As an aerogel material, wood sponge offers multi-action (absorption, filtration) and reusable oil–water separation functions. This paper introduces the advantages of the use of wood sponge for oil–water separation. The physical and chemical properties of wood sponge and its mechanism of adsorbing crude oil are explained. The synthesis method and the properties are discussed. Finally, the use of wood sponge is summarized and prospected. Full article
(This article belongs to the Special Issue Recent Developments in Wood Polymer Composites)
►▼ Show Figures

Figure 1

21 pages, 6156 KiB  
Article
Investigations of the Laser Ablation Mechanism of PMMA Microchannels Using Single-Pass and Multi-Pass Laser Scans
by Xiao Li, Rujun Tang, Ding Li, Fengping Li, Leiqing Chen, Dehua Zhu, Guang Feng, Kunpeng Zhang and Bing Han
Polymers 2024, 16(16), 2361; https://doi.org/10.3390/polym16162361 - 21 Aug 2024
Viewed by 513
Abstract
CO2 laser machining is a cost effective and time saving solution for fabricating microchannels on polymethylmethacrylate (PMMA). Due to the lack of research on the incubation effect and ablation behavior of PMMA under high-power laser irradiation, predictions of the microchannel profile are [...] Read more.
CO2 laser machining is a cost effective and time saving solution for fabricating microchannels on polymethylmethacrylate (PMMA). Due to the lack of research on the incubation effect and ablation behavior of PMMA under high-power laser irradiation, predictions of the microchannel profile are limited. In this study, the ablation process and mechanism of a continuous CO2 laser machining process on microchannel production in PMMA in single-pass and multi-pass laser scan modes are investigated. It is found that a higher laser energy density of a single pass causes a lower ablation threshold. The ablated surface can be divided into three regions: the ablation zone, the incubation zone, and the virgin zone. The PMMA ablation process is mainly attributed to the thermal decomposition reactions and the splashing of molten polymer. The depth, width, aspect ratio, volume ablation rate, and mass ablation rate of the channel increase as the laser scanning speed decreases and the number of laser scans increases. The differences in ablation results obtained under the same total laser energy density using different scan modes are attributed to the incubation effect, which is caused by the thermal deposition of laser energy in the polymer. Finally, an optimized simulation model that is used to solve the problem of a channel width greater than spot diameter is proposed. The error percentage between the experimental and simulation results varies from 0.44% to 5.9%. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
►▼ Show Figures

Figure 1

24 pages, 5254 KiB  
Review
Exploring the Potential Applications of Wool Fibers in Composite Materials: A Review
by Alessia Patrucco, Marina Zoccola and Anastasia Anceschi
Polymers 2024, 16(16), 2360; https://doi.org/10.3390/polym16162360 - 20 Aug 2024
Viewed by 779
Abstract
The use of renewable resources in composite materials is a vital strategy for enhancing sustainability in material science. Wool fibers are promising due to their unique properties, including thermal insulation and self-extinguishing characteristics. However, a substantial portion of wool is deemed unsuitable for [...] Read more.
The use of renewable resources in composite materials is a vital strategy for enhancing sustainability in material science. Wool fibers are promising due to their unique properties, including thermal insulation and self-extinguishing characteristics. However, a substantial portion of wool is deemed unsuitable for textiles and is often discarded as waste. This review investigates the integration of wool fibers into polymer composites, aiming to improve sustainability and material performance. By analyzing recent advancements, this study highlights the potential of wool fibers to enhance the mechanical, thermal, and acoustic properties of composites. The findings support the development of eco-friendly materials that contribute to waste reduction and promote sustainable practices across various industries. Full article
(This article belongs to the Special Issue Polymer Nanofibers and Fiber Composites)
►▼ Show Figures

Figure 1

18 pages, 8249 KiB  
Article
Examining the Flexural Behavior of Thermoformed 3D-Printed Wrist–Hand Orthoses: Role of Material, Infill Density, and Wear Conditions
by Daniel Vlăsceanu, Diana Popescu, Florin Baciu and Constantin Stochioiu
Polymers 2024, 16(16), 2359; https://doi.org/10.3390/polym16162359 - 20 Aug 2024
Viewed by 455
Abstract
This paper examined the mechanical properties of wrist–hand orthoses made from polylactic acid (PLA) and polyethylene terephthalate glycol (PETG), produced through material extrusion with infill densities of 55% and 80%. These orthoses, commonly prescribed for wrist injuries, were 3D-printed flat and subsequently thermoformed [...] Read more.
This paper examined the mechanical properties of wrist–hand orthoses made from polylactic acid (PLA) and polyethylene terephthalate glycol (PETG), produced through material extrusion with infill densities of 55% and 80%. These orthoses, commonly prescribed for wrist injuries, were 3D-printed flat and subsequently thermoformed to fit the user’s hand. Experimental and numerical analyses assessed their mechanical resistance to flexion after typical wear conditions, including moisture and long-term aging, as well as their moldability. Digital Imaging Correlation investigations were performed on PLA and PETG specimens for determining the characteristics required for running numerical analysis of the mechanical behavior of the orthoses. The results indicated that even the orthoses with the lower infill density maintained suitable rigidity for wrist immobilization, despite a decrease in their mechanical properties after over one year of shelf life. PLA orthoses with 55% infill density failed at a mean load of 336 N (before aging) and 215 N (after aging), while PETG orthoses did not break during tests. Interestingly, PLA and PETG orthoses with 55% infill density were less influenced by aging compared to their 80% density counterparts. Additionally, moisture and aging affected the PLA orthoses more, with thermoforming, ongoing curing, and stress relaxation as possible explanations related to PETG behavior. Both materials proved viable for daily use, with PETG offering better flexural resistance but posing greater thermoforming challenges. Full article
(This article belongs to the Special Issue Mechanical and Physical Properties of 3D Printed Polymer Materials)
►▼ Show Figures

Figure 1

16 pages, 17053 KiB  
Article
Polygonatum sibiricum Polysaccharides Alleviate Depressive-like Symptoms in Chronic Restraint Stress-Induced Mice via Microglial Regulation in Prefrontal Cortex
by Zhong-Yu Yuan, Xuan Zhang, Zong-Zhong Yu, Xin-Yu Wang, Zi-Heng Zeng, Meng-Xuan Wei, Meng-Ting Qiu, Jun Wang, Jie Cheng and Li-Tao Yi
Polymers 2024, 16(16), 2358; https://doi.org/10.3390/polym16162358 - 20 Aug 2024
Viewed by 398
Abstract
Microglia respond to stressors by secreting cytokines or growth factors, playing a crucial role in maintaining brain homeostasis. While the antidepressant-like effects of Polygonatum sibiricum polysaccharides (PSPs) have been observed in mice, their potential effectiveness involving microglial regulation remains unknown. This study investigates [...] Read more.
Microglia respond to stressors by secreting cytokines or growth factors, playing a crucial role in maintaining brain homeostasis. While the antidepressant-like effects of Polygonatum sibiricum polysaccharides (PSPs) have been observed in mice, their potential effectiveness involving microglial regulation remains unknown. This study investigates the antidepressant-like mechanism of PSP by regulating microglial phenotype and signaling pathways in the prefrontal cortex of chronic restraint stress (CRS)-induced mice. PSP was extracted, purified, characterized, and orally administered to CRS mice. High-performance gel permeation chromatography (HPGPC) revealed that PSP has a molecular weight of 5.6 kDa. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that PSP exhibited a layered structure with densely packed, irregular surfaces. PSP treatment significantly increased sucrose preference (low: 71%, p < 0.01; medium: 69%, p < 0.05; high: 75%, p < 0.001 vs. CRS: 58%) and reduced immobility time (low: 74 s, p < 0.01; medium: 68 s, p < 0.01; high: 79 s, p < 0.05 vs. CRS: 129 s), indicating the alleviation of depressive-like behaviors. PSP inhibited microglial activation (PSP, 131/mm2 vs. CRS, 173/mm2, p = 0.057), reversing CRS-induced microglial hypertrophy and hyper-ramification. Furthermore, PSP inactivated microglial activation by inhibiting NLRP3/ASC/caspase-1/IL-1β signaling pathways, increasing BDNF synthesis and activating brain-derived neurotrophic factor (BDNF)-mediated neurogenesis (PSP, 80/per DG vs. CRS, 49/per DG, p < 0.01). In conclusion, PSP exerts antidepressant-like effects through the regulation of microglial activity and neuroinflammatory pathways, indicating it as a potential natural compound for depression treatment. Full article
(This article belongs to the Special Issue Biopolymer-Based Materials in Medical Applications)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-155
Previous Issue
Next Issue
Back to TopTop