Polymer International最新文献

Rigid polyurethane foam (RPUF) was prepared using hydrolyzed keratin-modified polyol and aluminium hypophosphite as flame retardants. The effects of aluminium hypophosphite on the thermal stability and flame-retardant properties of hydrolyzed keratin-modified RPUFs were studied by limiting oxygen index (LOI) method, thermogravimetric analysis, pyrolysis kinetic analysis, cone analysis and smoke density analysis. The results showed that RPUF added with 7.5 wt% aluminium hypophosphite (RPUF-HK5-7.5AL) had the highest LOI, which was 26.1%. RPUF-HK5-7.5AL had the highest initial decomposition temperature, the highest T_5% at a heating rate of 10 °C min⁻¹ and the highest activation energy. In addition, RPUF-HK5-7.5AL possessed the lowest heat release rate at 50 kW m⁻² of 125.10 kW m⁻², and the lowest total heat release rate of 5.30 MJ m⁻². Results indicated that RPUF-HK5-7.5AL had the best thermal stability and flame-retardant properties. Scanning electron microscopy showed that hydrolyzed keratin and aluminium hypophosphite had a synergistic effect on the flame retardancy of the RPUFs. The current research results provide a useful reference for the preparation of RPUFs with good flame-retardant properties by bio-based modification. © 2024 Society of Industrial Chemistry.

In order to expand the application of biobased polycarbonate in optical components, a series of isosorbide polycarbonate (PICC)/rare earth ion complex fluorescent composites were prepared by using PICC as a macromolecular ligand and Eu³⁺ and Tb³⁺ as rare earth luminescence centers. The coordination system between rare earth ions and PICC was investigated by Fourier transform infrared spectroscopy, DSC and TGA. On adjusting the ratio of Eu³⁺ and Tb³⁺, a PICC/rare earth ion composite with adjustable fluorescence color was obtained. Also, the thermal, mechanical and optical properties of a series of PICC/rare earth ion fluorescent films with different ratios were tested. A transparent fluorescent composite material with excellent mechanical properties and tunable fluorescent colors has been prepared. © 2024 Society of Industrial Chemistry.

The weak interfacial adhesion of aramid fibers (AFs) in rubber composites can be improved by modifying their surface structure. Herein, modified AFs with a high grafting rate were prepared by modification using glycidyl polyhedral silsesquioxane (POSS) assisted with supercritical carbon dioxide (scCO₂). X-ray photoelectron spectroscopy confirmed the chemical bonding between AFs and glycidyl POSS. Thermogravimetric analysis and scanning electron microscopy images showed that POSS was grafted uniformly and the surface roughness enhanced obviously. After grafting the rubber with 5 wt% glycidyl POSS assisted with scCO₂, the surface grafting rate reached 12.26% and surface crystal spacing increased. The grafted layer on the modified AF surface was uniform, and the tensile strength of the modified fiber increased by 7.98%. Short AF-reinforced carbon black/styrene butadiene rubber (AF/CB/SBR = 2/50/100 phr) composites were prepared to investigate the adhesion strength between modified AFs and SBR. The reduction in tan δ of the composites confirmed the improvement in the interfacial adhesion strength. The tensile strength and modulus at 100% elongation of the composites increased by 15.13% and 25.77%, respectively, and the relative interface slip increased by 23.26%. Moreover, the cutting resistance of the composites showed a dramatic improvement, particularly for grafting with 5% glycidyl POSS assisted with scCO₂. © 2024 Society of Industrial Chemistry.

Towards the goal of developing renewable, biocompatible and intelligent polymer materials, natural Eucommia ulmoides gum (EUG) was modified via epoxidation and then the epoxidized EUG (EEUG) was compounded with another sustainable and biobased polymer, polylactic acid (PLA), to develop shape memory thermoplastic vulcanizates (TPVs) through reactive blending. The prepared PLA/EEUG TPVs displayed not only enhanced toughness but also greatly improved shape recovery ability, which was generated from the co-continuous phase structure and excellent interfacial adhesion induced by in situ compatibilization during reactive blending. It is shown that dicumyl peroxide content exerted little influence on the toughness of the TPVs. However, heat-triggered shape memory effects of the TPVs were significantly affected by the dicumyl peroxide content with a decrease in deformation ratio (Δε) from 163.51% to 128.36% and an increase in shape recovery ratio (R_r) from 73.32% to 91.93%. The findings of the present study offer an idea for the industrialization of biocompatible and smart materials for biomedical applications. © 2024 Society of Industrial Chemistry.

Poly[(3-hydroxybutyrate)-co-(4-hydroxybutyrate)] (P34HB), poly[(butylene succinate)-co-(butylene furandicarboxylate)] (PBSF) and poly(vinyl acetate) (PVAc) were melt-blended to prepare P34HB/PBSF/PVAc blends with improved ductility. The thermal properties, mechanical properties, rheological properties and morphology of the blends were systematically studied. The addition of PBSF promoted the melt crystallization of P34HB. The temperatures at 5% weight loss of the blends were higher than that of P34HB. The surface of the blends was investigated using scanning electron microscopy. The surface of P34HB was very smooth, but the surfaces of the blends were rough. PVAc can increase the compatibility between P34HB and PBSF. Compared with P34HB, the elongation at break of the blends was increased to 219.1%. © 2024 Society of Industrial Chemistry.

Organic polymers are of interest due to their numerous promising potential applications in the area of energy harvesting and sensing. In this context, piezoelectric and ferroelectric polymers are subject to intense research; however, it is challenging to understand polarization switching in such systems. The focus of the present study is to thoroughly evaluate the finer details of polarization reversal in poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) thin films. The intrinsic features arising from the true values of (switching) polarization and extrinsic features associated with the presence of non-switching contributions, i.e. leakage current and linear dielectric component, have been investigated using the positive-up–negative-down technique. These contributions are quantified and discussed. Furthermore, fatigue endurance has been examined by repeated switching cycles. Increase in polarization increases is associated with the improved crystallinity and enhancement of the β-phase. However, a higher degree of crystallinity, for extended numbers of repeated cycles of the bipolar electric field, resulted in degradation of the (switching) polarization. Fatigue significantly affects the leakage and ferroelectric components while the paraelectric contribution remains almost constant. The underlying mechanism of such trends are discussed in terms of hysteresis losses. © 2023 Society of Industrial Chemistry.

This paper investigates the influence of bamboo fibre loadings (30, 40, 50 and 60 wt%) on the physical, tensile and dimensional behaviour of short-bamboo-fibre-reinforced bio-epoxy matrix composites. Water absorption, thickness swelling, density, void content, tensile and thermomechanical analysis were determined. The findings indicated that higher fibre loading led to elevated water absorption and increased thickness swelling in bamboo fibre composites. The order of thickness swelling and water absorption behaviour was bio-epoxy < B-30 < B-40 < B-50 < B-60. Similarly, the measured density of composites increased with respect to fibre loading. However, the void content decreased when the fibre loading was >40 wt%. Concerning tensile characteristics, it was observed that all composite materials displayed lower tensile strength compared to the bio-epoxy matrix. However, there was a notable enhancement in the elasticity of the composites. As an example, B-60 exhibited the highest Young's modulus at 7.33 GPa. The analysis of the fracture behaviour of tension-tested samples was conducted using images obtained from SEM. The coefficient of thermal expansion was increased drastically as fibre loading increased. This indicated that the dimensional change was higher. Thus, it is desirable to have lower fibre loading to obtain better dimensional stability under the influence of temperature. © 2023 Society of Industrial Chemistry.

Highly hydrophilic and antifouling poly(vinylidene fluoride) (PVDF) ultrafiltration membranes are developed with excellent permeation using a zirconium-based metal–organic framework (MOF-801). MOF-801 is synthesized by a solvothermal method using zirconium(IV) oxychloride octahydrate (ZrOCl₂⋅8H₂O) and fumaric acid. The chemical functionality of MOF-801 is studied by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) whereas surface morphology and elemental composition are probed by scanning electron microscopy (SEM)/energy-dispersive X-ray analysis (EDX). The PVDF/MOF-801 membranes are characterized in terms of FTIR, XRD, FESEM/EDX and atomic force microscopy. The performance of the hybrid PVDF/MOF-801 membranes in terms of pure water flux and antifouling ability is found to be improved compared with bare PVDF membranes. The wettability of the membranes is measured by water contact angle and found to be 76.7° for bare PVDF membrane, which decreases upon the addition of MOF-801 to 55.1° due to the increase in surface hydrophilicity. A notable increase in roughness of 226.29 nm and a porosity of 67.91% is observed for the addition of 2 wt% MOF-801 in PVDF membrane matrix. The flux recovery ratio of the hybrid membrane is increased from 66.4% to 89.6% and from 68.3% to 85.2% for bovine serum albumin (BSA) and humic acid (HA) separation, respectively. In addition, the reversible and irreversible fouling performance during the rejection of BSA (93%) and HA (88%) indicates the enhanced antifouling property of the PVDF/MOF-801 membranes. A zone of inhibition test evidences the outstanding antibiofouling activity of the PVDF/MOF-801 membranes against E. coli and S. aureus. Overall results demonstrated the suitability of hybrid PVDF/MOF-801 membranes for water and wastewater treatment. © 2023 Society of Industrial Chemistry.