Journal of Polymer Research最新文献

Acrylonitrile Butadiene Rubber (NBR) and Polyvinyl Chloride (PVC) blends are popular in rubber product manufacturing for their flexibility, strength, oil resistance, and durability. Their combination enhances mechanical properties, thermal stability, and chemical resistance, making them ideal for industrial uses like hoses, seals, and insulation. This research work aims to interpret the mechanical properties and interfacial interaction of the NBR/PVC blend with graphene as a reinforcing filler. The morphology and dynamic mechanical properties of 50/50 and 70/30 (w/w) NBR/PVC blend vulcanizates revealed an uniform mixing. In X-ray diffraction studies, an increase in interlayer spacing was evident up to 5 phr graphene. The dynamic viscoelastic properties were used to report the activation energy and α-relaxation of NBR-PVC 70/30, 50/50 neat and graphene filled vulcanizates. The α-relaxation frequency of the filled compositions exhibited a gradual decline as the graphene content increased, while concurrently witnessing a reduction in the breadth of the loss factor peak. The storage modulus increased with increasing the graphene content. The interaction parameter of all compositions was determined by a theoretical expression based on the storage modulus at 10, 50, 100, 500 and 1000 Hz. The 50/50 blend of NBR and PVC was seen to have a greater interaction parameter than the 70/30 blend. However, among the NBR-PVC 70/30 blend compositions, the interaction was highest for 5 phr graphene, and reduced with further incorporation of graphene. Many studies lack information on the interaction of graphene with the rubber matrix. Hence, this research could enhance the understanding of how graphene disperses within the rubber matrix, its influence on mechanical and viscoelastic properties of NBR/PVC rubbers.

Aromatic bismaleimide (BMI)-based copolymers composed of alternating BMI and bis(sulfanediylethoxy)ethylene units of short and long lengths are synthesized and crosslinked via the reversible Diels–Alder reaction, resulting in thermoreversible amorphous networks with different structures and hence properties. The structure of BMI-based copolymers was confirmed by ¹H nuclear magnetic resonance (NMR) spectroscopy, and the occurrence of the DA reaction forming networks was followed using Fourier transform infrared (FT-IR) analysis. A comparison of the properties of the networks was obtained vis differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and wide-angle powder X-ray diffraction (XRD), optical microscopy, field-emission scanning electron microscopy (FE-SEM) and tensile measurements. Owing to higher mobility of the network structure derived from the long copolymer precursor, the corresponding network exhibits a lower glass transition and much better healing ability of scratches and cuts than for the short precursor-derived one. Efficient healing of complete cut, with strength and ultimate strain recoveries of 80% and 73%, respectively, are achieved for the long precursor-derived material.

By free radical polymerizing methylacrylylethyl trimethyl ammonium chloride (DMC), styrene (ST), and methoxy polyethylene glycol acrylate (MPEGA), a novel type of hydrophilic polymer antistatic agent (PDSM) was created. By utilizing FT-IR and ¹H NMR, the structure and properties of the PDSM copolymer were investigated. By using the melt blending approach, composites made of ABS (acrylonitrile-styrene-butadiene copolymer)/PDSM were generated. The composites’ mechanical characteristics and surface resistivity were measured. The results indicated that PDSM was evenly dispersed on the inner surface of ABS resin, resulting in a continuous conductive network, and serving the intended function of long-lasting antistatic. The surface resistance of ABS composites could be greatly decreased using the PDSM copolymer antistatic agent. Surface resistivity of ABS/PDSM composites were around 10⁹-10¹⁰ Ω when the proportion of PDSM copolymer was up to 15 wt%. As MPEGA concentration increased, the surface resistivity of ABS/PDSM materials declined because MPEGA comprised hydrophilic ether bonds and flexible side chains.

The isothermal non-solvent induced phase separation (NIPS) process was utilized to produce asymmetric polyethersulfone (PES) membranes in order to assess the effects of coagulation bath temperature (CBT) on their morphology and performance. The experimental process involved the use of quaternary dopes that were composed of glycerol, poly(vinylpyrrolidone) (PVP), γ-butyrolactone (GBL), and PES. Membranes were cast and precipitated in coagulation baths at temperatures of 22 °C, 30 °C, 40 °C, and 50 °C. Higher CBT has a significant effect on the membrane structure, leading to an increase in pore sizes from 18.51 nm to 40.36 nm, while maintaining approximately 80% porosity and the formation of interconnected microporous channels at temperatures from 30 °C to 50 °C. These structural enhancements played a crucial role in enabling the membranes to achieve remarkably high water flux rates, which range from 2000 to 4000 L m⁻² h⁻¹ bar ⁻¹. This achievement demonstrates the membranes exceptional performance and their advanced capability for use in ultrafiltration applications.

Maleic anhydride (MA) can function as both a grafting agent and a thermoplastic vulcanizate (TPV) agent or crosslinker in thermoplastic elastomer (TPE) blends of polylactic acid (PLA) and epoxidized natural rubber (ENR), depending on the degree of crosslinking. To validate the claim, a set of formulations with MA ranges from 0 to 2.0 phr was added to the PLA/ENR blend at different matrix blend ratios and compounding sequences. To distinguish the types of networks responsible for altering the blend’s phase and melt flow behaviour, various tests including mechanical, rheological, viscoelasicity validation, visual imaging, thermal analysis and spectroscopy testing of X-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR) were conducted. The results revealed that, without the presence of MA, the blends behave as typical thermoplastic elastomers (TPEs). Meanwhile, the addition of MA enhances the tensile properties and modifies the blend microstructure, indicating the presence of a coupling effect in the PLA/ENR blend. With further inclusion of more MA inside the blends, the rise in crosslinking degree transforms the blend into a thermoplastic vulcanizate (TPV) compound. Interestingly, in the molten state, the TPV blends exhibit dilatant flow behaviour, which is in contrast with the shear-thinning flow pattern of PLA.

Natural fiber composites (NFCs) are widely recognized for their eco-friendliness, cost-effectiveness, and mechanical properties. However, banana fiber natural composites (BFNCs) often suffer from moisture sensitivity and weak interfacial bonding due to the high lignin content. To overcome these limitations, this study explores the effect of incorporating 2-bromobenzonitrile functionalized graphitic carbon nitride (F/g-C₃N₄) as nanofillers in BFNCs. The BFNCs were fabricated with varying nanofiller concentrations (0, 0.25, 0.5, 0.75, and 1 wt%). Results demonstrated that the composite with 0.75 wt% F/g-C₃N₄ exhibited enhanced tensile strength (126.8 MPa), flexural strength (135.9 MPa), and impact strength (26.9 J/m) compared to pristine BFNC. Additionally, thermal stability was improved, as shown by DTA results. These properties indicate that the novel F/g-C₃N₄ fused BFNCs are strong candidates for applications in the electrical industry, such as printed circuit boards (PCBs) and insulating materials. The incorporation of F/g-C₃N₄ nanofillers in BFNCs offers a promising advancement, significantly improving mechanical, thermal, and structural properties, positioning this composite as a sustainable alternative to conventional materials.

The synthesis of foaming prepolymers based on esterified dianhydride of 3,3',4,4'-benzophenone tetracarboxylic acid in the presence of three alcohols (methanol, ethanol, isopropanol) and 4,4'-diaminodiphenylmethane was carried out. The influence of the nature of the used alcohol on the duration of dianhydride esterification and on the properties of the formed polyimide foams was shown. The process of formation of diesters of 3,3',4,4'-benzophenone tetracarboxylic acid and the structure of the resulting polyimide foams were investigated by IR spectroscopy. A comparative study of the mechanical and thermal properties of polyimide foams obtained using various alcohols was carried out. The structure of the obtained polyimide foams was studied by scanning electron microscopy. It was found that the use of methanol allows one to obtain more rigid foams, and ethanol—more elastic ones. The density of the synthesized foam materials ranged from 7.41 to 9.15 kg/m³, and the elastic modulus was equal to 39–120 kPa. All obtained foam samples demonstrate high heat resistance.

Annealing is a heat treatment process for materials. In this study, a conductive hydrogel was synthesized by a one-pot method using three raw materials: polyvinyl alcohol(PVA), carboxylated carbon nanotubes(Multi-Walled Carbon Nanotubes-COOH, MWCNTs-COOH) and polyethyleneimine (PEI). Based on the traditional freeze-thaw method for the preparation of PVA-based hydrogels, the annealing treatment was further added here to enhance the mechanical properties and fatigue resistance of the hydrogels. The synthesized conductive hydrogels were annealed in oven at different temperatures for a certain time, and the optimized experimental conditions and results were: the mechanical properties of the conductive hydrogel were best improved under the condition of 100 ℃-20 min, with the ultimate stress of 30.8 MPa and toughness as high as 779.58 MJ/m³. A high-strength, fatigue-resistant conductive hydrogel was successfully prepared, and its mechanical properties far exceeded those of other conductive hydrogels. Through a series of tests such as X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), it was found that annealing promotes the orderly arrangement of PVA chains and crystallization through high temperatures, so as to enhance the mechanical properties of hydrogels. As a relatively simple and inexpensive annealing post-treatment technique, it is expected to be more widely used in improving the mechanical properties of hydrogels.

This study examines the impact of gamma radiation on the mechanical characteristics of carbon/Kevlar hybrid epoxy composites used in aerospace applications. Composites consisting of carbon (CCCC), Kevlar (KKKK), and hybrid (CKCK) fabrics with varied stacking sequences were produced using a hand lay-up technique. These composites were then exposed to different dosages of gamma radiation (1 kGy, 3 kGy, and 5 kGy ). A thorough mechanical analysis was conducted, encompassing tests for tensile strength, flexural strength, impact resistance, interlaminar shear strength (ILSS), hardness, and water absorption. The carbon composite that was not exposed to radiation demonstrated the maximum tensile strength, measuring 246.28 MPa. Additionally, it exhibited a flexural strength of 787.72 MPa and an interlaminar shear strength (ILSS) of 9.75 MPa. After being exposed to a radiation dose of 5 kGy, the values decreased to 215.36 MPa, 578.49 MPa, and 8.71 MPa, respectively. Among the materials that were examined, the hybrid composite had the highest impact strength of 0.0537 J/mm2. The results of dynamic mechanical analysis showed a reduction in the storage modulus from 11762.1 MPa to 10338.7 MPa, and a decrease in the glass transition temperature from 113.05 °C to 107.7 °C following exposure to 5 kGy of radiation. The scanning electron microscopy (SEM) analysis of fractured surfaces revealed a transition from a ductile to a brittle fracture behaviour as the radiation doses increased.

This work introduces the fabrication of eco-friendly poly (ε-caprolactone) based polymeric membranes for water filtration applications by a non-solvent induced phase inversion method by using N-methyl pyrrolidone as solvent and water as non-solvent. The membranes are prepared with good morphological features and permeation properties to fit filtration applications by varying the polymer concentration in the dope solutions in the range of 10-18%. The thermal, mechanical, chemical composition, and surface roughness properties of the fabricated poly (ε-caprolactone) membranes were studied by thermo gravimetric analysis (TGA), universal testing machine (UTM), fourier transform infrared spectroscopy (ATR-FTIR), and atomic force microscopy (AFM) respectively. Morphological studies of the membranes showed a porous asymmetric structure with different skin layer morphology. Precipitation kinetics studied by cloud point measurement showed instantaneous demixing during precipitation resulting in fingerlike morphology. Hydrophilicity and the performance of the prepared membranes for filtration applications were analyzed by contact angle measurements, equilibrium water content, porosity, and pure water flux. Pore size measured using ImageJ software and the Guerout–Elford– Ferry equation assures the utility of the membranes for the microfiltration process. The soil degradability of the fabricated membranes was also evaluated and the efficiency of the fabricated membranes for oil/water separation was studied with olive oil-water emulsion. All the results obtained revealed the dependence of membrane properties and performance on the casting solution composition.

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