Journal of Applied Polymer Science最新文献

The nanofiltration (NF) membrane has not been extensively competent for rejection of monovalent ions (such as Cl⁻ and NO₃⁻), and the strategy for enhancing monovalent ion rejection and permeation flux still faces a significant challenge. Herein, based on our previous polyethersulfone (PES)-type NF membrane (NF-0), two novel NF membranes were fabricated with additional incorporations of 2,2′-benzidinedisulfonic acid (BDSA) and forward osmotic extraction solution-functioned nanoparticles (MNPs) to remove nitrate from the aqueous solution. The fabricated NF-BDSA membrane with introduction of BDSA in ultrathin layer displays a significant nitrate rejection of 92.2% and an acceptable permeation flux of 21 L m⁻¹ h⁻¹ at 0.6 MPa. As anticipated, the obtained NF-MNPs1.0 membrane with additional incorporation of MNPs (1.0 wt% addition) in the substrate layer of NF-BDSA membrane achieves further improvements in nitrate rejection (95%) and water permeability (32.3 L m⁻¹ h⁻¹); encouragingly, this membrane exhibits comparable monovalent ion rejection and permeation flux to reverse osmosis membrane under relatively low pressure. Compared with those of NF-0 membrane, the permeation flux and nitrate rejection of NF-MNPs1.0 membrane increase by 111.1% and 6.1%, respectively. Moreover, the superior performances of endurance, antifouling and chlorine resistance of NF-MNPs1.0 membrane demonstrate its expectable perspective of potential engineering applications.

By combination of UV curing and frontal polymerization, interpenetrating polymer networks (IPNs) based on diglycidyl ether of bisphenol-A (DGEBA) epoxy resin and polydicyclopentadiene (PDCPD) were prepared by UV-induced simultaneously frontal polymerization in this paper. Compared with the net DGEBA cured polymer, the tensile strength, elongation at break and impact strength of the IPNs were simultaneously improved. The maximum tensile strength and elongation at break of the IPNs reached 100 MPa and 4.64%, respectively, and the maximum impact strength reached 7.34KJ/m² with an improvement of 115.2% over that of the net DGEBA cured polymer. Thermogravimetric analysis (TGA) results revealed that the IPNs could enhance the thermal stability. Data of the differential scanning calorimetry (DSC) and TGA testing shows that the IPN shows a single glass transition temperature (T_g) which is between the T_g of DGEBA and DCPD, indicating homogeneous phase and highly cross-linked IPN formed. Morphologies and molecular structure of the IPNs polymer were observed by scanning electron microscope (SEM) and characterized by Fourier transform infrared spectroscopy (FTIR), respectively, whose results also proved the formation of ideal IPNs structures.

Increased recycling of plastics is an essential step toward a more sustainable use of materials, where some of the most challenging fractions are engineering materials and composites. Used pump houses prepared from glass fiber (GF)-reinforced blends of polyphenylene oxide (PPO) and high-impact polystyrene (HIPS) obtained through a take-back scheme (take-back, TB) were characterized and shredded for use in the preparation of new composites by injection molding. Initial degradation was observed on the surface of the TB parts; however, the core of the material was unaffected. Mechanical reprocessing of regrind and virgin material showed a reduction of tensile strength already at 10% regrind, which was attributed to fiber length reduction during reprocessing. At the same time, Young's modulus and extension at break were largely unaffected, confirming that 25% of TB could be included without any additional loss of properties. As a worst-case scenario, tests with extensively degraded material showed that Young's modulus and tensile strength would ultimately be reduced with an increasing amount of heavily degraded material and that a balance would have to be found between loss of properties and recycled content for heavily degraded material.

With the development of power systems and electronic devices, epoxy resin (EP) is facing increasingly severe operating environments, and its performance may not meet expectations. In order to broaden the application of EP, the DE/EP composite films were prepared with EP as matrix, polyacrylic rubber dielectric elastomer (DE) as reinforcement materials. The structure of DE/EP composite films was characterized by XRD, SEM, and other methods, and the electrical and thermal properties of the materials were tested and studied. The study found that with appropriate dissolution and stirring treatment, DE can be evenly dispersed in the EP matrix, and the introduction of DE does not significantly affect the structure of the EP molecular chain, also found the introduction of DE improve the electrical and thermal properties of EP. The breakdown strength of the 4% DE/EP composite film surpasses that of the pure EP film by 15.58%. Additionally, the thermal conductivity of the 8% DE/EP composite film is elevated by 41.6% compared to the pure EP film, while its dielectric constant is also enhanced by 8.2%. This work may provide a theoretical basis for studying the application of EP modified system in electrical engineering, integrated circuit packaging and other fields.

The development of efficient water purification technologies is a critical research focus driven by the crucial role of clean water sources for ecological sustainability. This study explores the strategic incorporation of nanoparticles within polyvinylidene fluoride (PVDF) membranes as a promising approach to enhance membrane performance for wastewater remediation. PVDF membranes containing varying ratios of graphene (GR) and titanium dioxide (TiO₂) nanocomposites were fabricated via phase inversion method. Characterization techniques including XRD, FTIR, and FESEM-EDX revealed that the 80% GR nanocomposite membrane exhibited desirable structural and functional properties with pronounced sponge-like morphology and homogenous nanoparticle distribution. Fourier-transform infrared spectroscopy and x-ray diffraction analysis confirmed the 80% GR membrane retained PVDF crystallinity while uniquely eliminating TiO₂ crystallinity. Subsequently, performance testing demonstrated the 80% GR nanocomposite membrane had the highest water flux and methylene blue dye rejection rates compared to other ratios and the pristine PVDF membrane. Both fabricated membranes exhibited sufficient reusability and antifouling properties. However, 80% GR ratio exhibited superior antifouling properties, indicating its potential as an optimal material for improving membrane hydrophilicity and overall water purification technologies. These findings underscore the strategic utility of GR-TiO₂ nanocomposites for enhancing PVDF membrane performance in sustainable wastewater treatment applications.

Polyimide materials with high mechanical strength are widely used in various fields, but pose certain challenges in achieving sustainable material utilization. A poly(imide-imide) vitrimer material (ADTA) based on multiple dynamic covalent bonds (imide, imine, and disulfide bonds) was constructed by preparing vanillin difunctionalized derivatives (DVA) for aldolamine condensation reactions with bis-amine monomers (ATFA) and tris(2-aminoethyl) amines (TAEA) with imide structures. The ADTA material has good 5% thermal stability T_d5% (278.87°C), high energy storage modulus E (2421.26 MPa), and fast relaxation time (36.39 s). The thermal stability and mechanical properties of the material are enhanced by the more stable alicyclic structure of the imide structure. The material also demonstrated excellent solvent resistance and self-healing properties. This study provides a new option for the development of sustainable utilization of polyimide materials.

As a highly effective nucleating agent, layered zinc phenylphosphonate (PPZn) is incorporated into polylactic acid (PLA) to investigate the epitaxial crystallization of PLA on PPZn in this study. The corresponding lattice spacing change, crystalline morphology, and crystalline structure are emphasized to reveal the epitaxial crystallization mechanism. As a result, with the increase of PPZn content and the annealing time, the increasing lattice spacing of PPZn and the formation of mutually perpendicular rodlike crystals are observed through x-ray diffraction (XRD) and polarized optical micrograph (POM) measurements, implying that the interlayer spacing of PPZn crystals is expanded as the PLA α-form crystals epitaxially grow on its surface, that is, epitaxial crystallization. To be specific, “edge on” lamellae epitaxial grow on the PPZn crystals along the [010] and [100] directions under two excellent lattice matchings, which possess acceptable mismatching of 0.347% and 7.5%, respectively. With the support of the epitaxial crystallization mechanism, the occurrence of the filamentous structure observed in the fracture morphology of PLA/PPZn composites suggests strong interfacial adhesion between PLA and PPZn, which makes the impact toughness of the PLA/PPZn composites increase by 53.6% compared with pure PLA.

Silicone rubber (SR) is an ideal dielectric elastomer substrate due to its excellent flexibility and fast response speed. However, the innate low dielectric permittivity (ε) of SR generally requires a rather high driving voltage that restricts its widespread application. Typical attempts to increase ε of SR usually deteriorate either its flexibility or electrical stability. Herein, conductive multi-walled carbon nanotube (MWCNT) were first surface modified with polyphenols (PNs) (MWCNT@PNs), aiming to facilitate its well dispersion within SR matrix, which may maintain the softness and electrical stability of SR via suppressing concentrated physical crosslinking and local leakage current flow. Then, five-layered MWCNT@PNs/SR composites were prepared with the outer two insulating layers of SR while middle three dielectric layers of MWCNT@PNs filled SR. The multilayered structure further hindered the formation of conductive pathways through the composites, promising a high breakdown strength of the composites. Therefore, the multilayered MWCNT@PNs/SR composites exhibited increased ε, maintained low Young's modulus and electrical breakdown strength compared with pure SR of the same five-layered structure. Among them, the composite with uniformly distributed MWCNT@PNs (m-1: 1: 1) showed a highest actuation strain of 11.9% (at 19.6 kV mm⁻¹), which was 4.1 times higher than that of SR (2.9% at 19.1 kV mm⁻¹).

Multicellular, thin-walled impact tubes have been intensely studied and used in various engineering fields in recent years due to their lightweight, high performance, ease of application, superior energy absorption, and stable deformation characteristics. In this study, energy absorption, crashworthiness performances, and deformation properties of thin-walled structures manufactured from polylactic acid (PLA+) and acrylonitrile butadiene styrene (ABS) using fused deposition modeling (FDM) technology were compared under quasi-static axial compression. Thin-walled structures consist of multicellular tubes connected by concentric corner-edge connections with square and hexagonal cross-sections. Experimental testing outcomes indicate that the energy absorption capacity increases with increasing the number of corners in multicellular structures. The tubes with square wall-to-wall (S-WW) and hexagonal wall-to-wall (H-WW) cross-sections exhibit superior crashworthiness performance compared to other cross-sections. Based on the experimental results, the absorbed energy by WW patterned PLA+ square tubes are 19%, 7%, and 46% more than that of wall-to-corner (WC), corner-to-wall (CW), and corner-to-corner (CC) patterned tubes, respectively, while it is 11%, 19%, and 80% more in hexagonal cross-section tubes, respectively. This study provides an informative reference for easier applicability of multicellular energy-absorbing structures with 3D-print and the design of corner-edge connections of internal connections in multicellular structures.