Polymer International最新文献

Fiber-reinforced composites have emerged as versatile materials with applications spanning diverse industries, driven by their exceptional mechanical properties and lightweight nature. This review provides a comprehensive overview of natural fiber-reinforced composites, focusing on their enhanced mechanical and functional properties achieved through modern processing techniques. The study delves into various manufacturing methods, such as thermoforming, additive manufacturing, compression molding, electro-spinning, pultrusion and autoclave molding, which have significantly contributed to the advancement of these composites. The review further investigates the multifaceted properties of these composites, which highlights the versatility and applicability of these materials and provides a holistic understanding of their potential applications. Additionally, the work addresses current research gaps and identifies prospects, shedding light on the evolving landscape of natural fiber-reinforced composites. The synthesis of processing techniques, material properties and potential applications offers valuable insights for researchers, practitioners and industries aiming to harness the full potential of these sustainable and high-performance materials. © 2024 Society of Chemical Industry.

In this study, amphiphilic thiosemicarbazone was used to align liquid crystal (4-cyano-4′-pentylbiphenyl) in a homeotropic way on polyimide containing alkyl pendent groups (AHDPI), which was coated on a glass slide. The amphiphilic ligands 2-(4-(dodecyloxy)benzylid-ene)hydrazine-1-carbothioamide (DT) and 2-(1-dodecyl-2-oxoindolin-3-ylidene)hydrazine-1-carbothioamide (IT) were doped with liquid crystal (LC) to develop LC-based sensors to detect Hg²⁺ ions in water. The selective interaction of carbothioamide with Hg²⁺ ions triggered the orientation transition of LC from homeotropic to parallel alignment and gave dark to bright optical signal at the LC/aqueous interphase. Self-immobilization of thiosemicarbazone-based ligands on AHDPI-coated glass slide can be used to detect Hg²⁺ ions with high sensitivity. The limit of detection with DT and IT was found to be 0.5 and 0.25 μmol L⁻¹, respectively. Density functional studies were carried out to study the interaction of the thiosemicarbazone ligands with mercuric ions, resulting in highly negative binding energies of −1.55 and −2.06 eV for DT and IT with Hg²⁺ ions, respectively. The chemical and thermal stability (up to 268 °C) of the AHDPI coated on glass slide made it reusable at least twice for sensor fabrication. This provides a quicker and cheaper alternative to traditional methods of sensor fabrication. © 2024 Society of Chemical Industry.

This study investigates the development and characterization of a novel composite material for structural applications, aiming to address the growing demand for lightweight, durable and versatile materials. The composite integrates aramid fibre reinforced with sawdust particulates within an epoxy matrix. Methodologically, the composite was fabricated using a hand layup process, ensuring even distribution and strong adhesion between components. Mechanical testing revealed significant enhancements in tensile strength (up to 135.29 MPa) and flexural strength (up to 136.92 MPa) with the inclusion of sawdust particulates, optimizing stress distribution and impact resistance. Hardness was also improved, peaking at a Rockwell hardness number of 94. Thermal analysis demonstrated moderate thermal conductivity (1.92 W mK⁻¹) and a high heat deflection temperature (109 °C), indicating excellent thermal stability. SEM provided insights into the composite's microstructure, confirming uniform sawdust distribution and robust fibre–matrix adhesion. These findings underscore the potential of this composite for lightweight, durable and thermally stable structural applications. © 2024 Society of Chemical Industry.

The objective of this work was to fabricate nanofibres composed of polycaprolactone (PCL) and κ-carrageenan (kC) by employing an anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT). This study examined the role of the surfactant in PCL/kC/AOT (hybrid) nanofibre preparation using SEM, AFM, Fourier transform infrared spectroscopy, XRD and DSC. The wettability and water uptake percentage of the nanofibres were investigated. An antimicrobial study was conducted against bacterial strains using a colony-counting assay, and changes in bacterial morphology were monitored using TEM. The results demonstrated that the hybrid nanofibres had a uniform and smooth structure, which might be attributed to the improved compatibility between polymers in the presence of the surfactant. The incorporation of AOT in the matrix resulted in a reduction in the mean fibre diameter and surface roughness. The hybrid nanofibres increased water absorbency is evidence of their high hydrophilicity, which can be explained by the simultaneous impact of kC and AOT. The hybrid nanofibres exhibited effective activity against Staphylococcus aureus and Escherichia coli. © 2024 Society of Chemical Industry.

This study aims to investigate the recycling of end-of-life computer plastics, focusing on polycarbonate (PC) and acrylonitrile–butadiene–styrene (ABS) copolymer, which constitute a significant portion of collected computers. Through differential scanning calorimetry and infrared spectroscopy analyses, the properties of raw PC, ABS and poly(methyl methacrylate) (PMMA) were evaluated. Various blends of PC and ABS were prepared, incorporating different percentages of recycled PMMA as a cost-effective coupling agent. These blends were processed through melt compounding using a contra-rotating twin-screw extruder and subsequently shaped by injection molding. An experimental mixture design was applied to evaluate the mechanical and physical properties of the composite materials, including melt flow index, hardness, flexural strain at break and Charpy impact strength. The results of the desirability analysis indicated that the optimal blend for achieving a balance between mechanical and physical properties consists of a high PC content (approximately 80% or more), a low ABS content (less than 20%) and less than 5% recycled PMMA. © 2024 Society of Chemical Industry.

A tetrafunctional glycidyl ether cyclic siloxane epoxy resin (TGTS) has been synthesized, characterized and cured with four aromatic amine hardeners: 1,3-phenylenediamine (PDA), diethyltoluenediamine (DETDA), 4,4-diaminodiphenylmethane (DDM) and 1,3-bis(4-aminophenoxy)benzene (APB). Each of the cured networks produces transparent and homogeneous networks, although when TGTS is cured with DETDA, reduced compatibility led to lower epoxide consumption, a more heterogenous microstructure and deleterious effects upon properties. Reduced miscibility of DETDA significantly impacts the chemical structure and microstructure of the network, resulting in significant reductions in thermal and mechanical properties but higher UV-A transmission. The PDA-, APB- and DDM-cured networks conversely were more miscible and display properties typical of organic–inorganic hybrid networks, such as good mechanical properties at ambient and sub-ambient temperatures, comparatively high glass transition temperatures, improved resistance to oxidation and lower UV-A transmission. © 2024 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

As a type of cellulose ether, cyanoethyl cellulose (CEC) is considered to be a promising candidate for polymer dielectrics due to its sustainable nature and high dielectric constant induced by the cyano groups. However, the relatively high conduction loss of CEC arising from the charge motion across the polymer degrades its dielectric properties. In this work, we designed and synthesized an all-organic polymer composite of CEC/itaconic anhydride (ITA) to improve dielectric properties. The CEC matrix was graft functionalized by ITA via an esterification reaction between the anhydride groups of ITA and hydroxyl groups of CEC. Meanwhile, crosslinking structure was also established in the composite by the generation of diester. Significantly improved dielectric constant (ε_r), elevated breakdown strength (E_b), restrained dielectric loss (tan δ) and decreased conductivity (σ) were observed in the composites compared with unmodified CEC. The ε_r increased from 17 for pure CEC to 32 for CEC/ITA at 1 kHz, and E_b also soared from 145 MV m⁻¹ for CEC to 226 MV m⁻¹ for the composite. The tan δ reduced from 0.24 for pure CEC to about 0.05 for the composite at 100 Hz. This should be attributed to the molecule trapping centers arising from the high electron affinity ITA and the formation of crosslinked networks as well as hydrogen bonding, which impeded the electric conduction. It also provided additional advantages of better dielectric properties for the CEC/ITA composites than pure CEC at high temperatures, which may offer inspiration for the design and preparation of bio-based dielectrics for high temperatures. © 2024 Society of Chemical Industry.