Journal of Polymer Research最新文献

In this study, a new hydrogel composite nanofiltration (NF) membrane was developed using a coating-crosslinking method with polyvinyl alcohol (PVA) and sodium alginate (SA) as the hydrogel coatings on a porous polyvinylidene fluoride (PVDF) substrate. The experimental findings demonstrated that the SA-PVA-PVDF hydrogel composite NF membrane exhibited excellent separation performance and good hydrophilicity. The optimum preparation conditions for the SA-PVA-PVDF hydrogel composite NF membrane included a 30-min coating period, the use of CaCl₂ as the preferred crosslinker, and a balanced ratio of SA to PVA at 1:1. The water flux of the hydrogel NF membrane was 54.6 L/(m²ˑh), with retention rates for Methylene blue, Congo red, and Coomassie brilliant blue at 91.4%, 95.6%, and 97.7%, respectively. In this paper, the preparation of high-performance calcium alginate hydrogel composite nanofiltration membrane will be helpful to develop a generation of composite membranes for dyeing wastewater separation.

The recent increase in world industrial activities has resulted in higher wastewater discharge containing potentially toxic species (PTEs) into the aquatic environment. This study aimed to evaluate the PES/mesomaterial-based mixed matrix membranes (MMMs) adsorption capacities for PTEs (Cd²⁺, Cr⁶⁺, Ni²⁺, and Pb²⁺) in different aqueous systems using a Doehlert design method. The MCM-41 synthesis was performed via the hydrothermal method and modified via the grafting method (NH₂-MCM-41 and SH-MCM-41). The MMMs were obtained by the phase inversion method. PTEs quantification was performed by inductively coupled plasma optical emission spectrometry (ICP OES). Preliminary adsorption results showed no significant differences between the membrane adsorption capacities for the PTEs studied. The in-depth study using the PES/SH-MCM-41-based MMMs (MMM-S) showed a significant influence of the independent variable X₂ (initial PTEs concentration) in the MMM-S adsorption capacities. Contrary, pH, contact time and amount of SH-MCM-41 into the MMMs does not significantly affect the adsorption process. Also, maximum adsorption capacity values of PTEs were observed in batch adsorption systems with an initial PTEs concentration of 0.332 mmol L⁻¹, at pH 5, under agitation (300 rpm) for 39 min and using a MMM synthesized with 6% of SH-MCM-41. In the permeation system, the MMM-S2 presented the best performance with the lowest permeability rates and the highest removal percentage of PTEs.

Graphical Abstract

As the amount of e-waste generated globally increases, there is a growing interest in biodegradable polymer composites for electronic devices. However, the use of the materials available today is limited due to their insufficient properties, such as thermal conductivity and stability in elevated temperatures. In this study, we promoted stereocomplex formation in composites based on an equimolar blend of L-PLA and D-PLA, filled with graphene nanoplatelets to enhance the thermal conductivity of the materials. Using Raman spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis, we demonstrated how such processing affects matrix composition and phase transitions. Although the graphene nanoplatelets did not favor the crystallization of stereocomplex, the wide-angle X-ray scattering experiment showed that its content in the composites increased to about 35%. As a result, their room temperature thermal conductivity rose by even 17% and further increased with the ambient temperature rise. The results were supplemented by directional measurements to determine the influence of morphological anisotropy.

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.