Journal of Applied Polymer Science最新文献

This study investigated the tribological properties of epoxy nanocomposites reinforced with graphene (Gr), graphene oxide (GO), and reduced graphene oxide (rGO) at concentrations of 0.15 and 0.6 wt%. Comprehensive structural characterization was performed using SEM, EDX, XRD, FTIR, and Raman spectroscopy to evaluate nanoparticle morphology, chemical composition, and crystal structure. Pin-on-disk wear tests assessed friction coefficient and weight loss under controlled conditions. SEM analysis revealed planar layered structures in Gr, while GO and rGO exhibited wrinkled morphologies due to oxygenated functional groups. EDX confirmed pure carbon composition (100%) in Gr, with oxygen content of 44.82 wt% in GO and 34.62 wt% in rGO. XRD analysis demonstrated interlayer distances of 0.34 nm, 0.78 nm, and 0.61 nm for Gr, GO, and rGO, respectively. FTIR and Raman spectroscopy confirmed stronger matrix interactions in GO due to functional groups, while Gr maintained superior structural order. Tribological testing revealed that Gr at 0.6 wt% exhibited optimal performance with 41.67% reduction in friction coefficient and 77.78% decrease in weight loss compared to neat epoxy. This superior performance is attributed to the well-ordered sp² layered structure and inherent lubricating properties of graphene. GO performed weakest, while rGO demonstrated intermediate behavior. These findings provide insights for designing epoxy nanocomposites with enhanced tribological properties for industrial applications.

Amid the global “double-carbon” initiative, melting-grafted polypropylene (PP) insulation presents a promising technical route for next-generation power cable systems due to its recyclability, satisfactory dielectric performance, and engineering practicality. However, its universality across both high-voltage alternating current (HVAC) and direct current (HVDC) systems remains to be fully assessed. In this study, we selected a mature polar grafted PP system: glycidyl methacrylate (GMA)-grafted PP, to experimentally evaluate its performance and elucidate the underlying physical mechanisms. The results demonstrate that GMA-grafted PP exhibits excellent DC dielectric performance, including a 24.6% enhancement in breakdown strength and significantly improved space charge distribution, whereas its performance under AC conditions remains unsatisfactory. The GMA-induced trapping-detrapping process is proved a key factor contributing to DC improvements, while the study also highlights that polymeric degradation during the melting grafting process, as well as the high polarity of GMA, are responsible for the unfavorable AC performance. In conclusion, 5% (weight percent) GMA-grafted PP is highly suitable for HVDC cable insulation, but the degradation associated with the melting grafting process is a crucial and urgent issue to be addressed, for the development and universality of high-capacity recyclable cable systems.

This study aimed to develop a highly water-selective membrane using low-cost monomers and inorganic fillers. Accordingly, TiO₂ and sodium montmorillonite (Na-MMT) clay filler incorporated terpolymer composites of poly(acrylonitrile-co-vinyl pyrrolidone-co-acrylic acid) were synthesized by in situ incorporation of different weight% of fillers during the emulsion polymerization of acrylonitrile (AN), 1-vinyl-2-pyrrolidinone (VP), and acrylic acid (AA) at different AN:VP:AA molar ratios. Several membranes were prepared from these composites by the solvent casting method. The polymer and the membranes were characterized. The sorption of 75–100 wt% isopropyl alcohol (IPA)-water mixtures in membranes was analyzed using Flory-Huggins thermodynamic interaction parameters, while the solvent clustering in the membranes was evaluated by the modified Engaged Species Induced Clustering model. The solvent diffusion through the membranes was analyzed using the total solution volume fraction (TSVF) model. The CP5 membrane, prepared with an AN:VP:AA molar ratio of 5:1:1, exhibited the best results for thickness-normalized flux (J _T ) and separation factor for water (α _PV ) by pervaporation. The CP5 membrane filled with 1 wt% Na-MMT clay and 0.5 wt% TiO₂ showed the highest J _T /α _PV of 8.55 kg/m² h μm/645.8 for the azeotropic IPA-water (87.5/12.5) binary mixture, with a good fit of permeation data to the TSVF model.

This study investigates the effect of cross-linker content in tailoring the structure–property correlation of a robust polymeric ionogel for acoustic sensor application. Ionogels are synthesized by incorporating 1-ethyl-3-methyl imidazolium ethyl sulfate [EMIM][EtSO₄] inside an acrylic acid-co-acrylamide copolymer (PAA-co-PAAm). Further, the influence of cross-linker N, N′-methylene bisacrylamide (MBAA) on various key properties required for ionogel to act as an acoustic sensor is studied by varying the concentration from 0.1 to 2 mol% relative to the monomer concentration. The formation of stable polymer-ionic liquid networks is confirmed using FTIR, DSC, and TGA. Higher cross-link density enhances thermal stability, environmental stability, and hardness, while decreasing the water absorption. The systematic constriction of the polymeric network, achieved by increasing MBAA, is quantified by determining cross-link density and microstructural parameters via rheological analysis. Electrochemical impedance spectroscopy (EIS) studies suggest that increased cross-link density elevated the bulk resistance (78–182 Ω), lowered the electrical double layer (EDL) capacitance (0.096–0.045 μF/cm² at 1 kHz), and ionic conductivity (1.0 × 10⁻³ to 4.4 × 10⁻⁴ S/cm). Frequency-dependent capacitance profiles show stronger drop-downs at lower frequencies for loose polymer networks formed at low cross-link density, revealing their enhanced ionic mobility and interfacial charging. Further, in this study, an ionogel acoustic sensor is fabricated, which detected acoustic signals in all the applied frequencies (1–10 kHz). Thus, this work is a novel attempt that highlights the solemn role of cross-link density in governing the electrochemical responsiveness of an ionogel and presents the potential of ionogel-based highly sensitive, futuristic, flexible conformal acoustic sensors.

Amid the global “double-carbon” initiative, melting-grafted polypropylene (PP) insulation presents a promising technical route for next-generation power cable systems due to its recyclability, satisfactory dielectric performance, and engineering practicality. However, its universality across both high-voltage alternating current (HVAC) and direct current (HVDC) systems remains to be fully assessed. In this study, we selected a mature polar grafted PP system: glycidyl methacrylate (GMA)-grafted PP, to experimentally evaluate its performance and elucidate the underlying physical mechanisms. The results demonstrate that GMA-grafted PP exhibits excellent DC dielectric performance, including a 24.6% enhancement in breakdown strength and significantly improved space charge distribution, whereas its performance under AC conditions remains unsatisfactory. The GMA-induced trapping-detrapping process is proved a key factor contributing to DC improvements, while the study also highlights that polymeric degradation during the melting grafting process, as well as the high polarity of GMA, are responsible for the unfavorable AC performance. In conclusion, 5% (weight percent) GMA-grafted PP is highly suitable for HVDC cable insulation, but the degradation associated with the melting grafting process is a crucial and urgent issue to be addressed, for the development and universality of high-capacity recyclable cable systems.

The growing demand for multifunctional polymers accelerates the development of materials integrating high strength, rapid self-healing, photoluminescence, and controlled biodegradability. In this work, a custom-designed naphthylimide-based hyperfluorescent compound (AHHN) with a rigid conjugated structure is incorporated as a chain extender into the matrix of a waterborne polyurethane (WPU). The obtained multifunctional WPU-AHHN simultaneously exhibits fluorescence, UV absorption, autonomous self-healing, and biodegradability. Abundant amide groups within AHHN serve as hydrogen-bond donors and acceptors, forming robust physical crosslinks with N, O, and H atoms in the polyurethane backbone. This hydrogen-bond network promotes microphase separation, significantly enhancing thermal stability, mechanical strength (tensile strength: 26.8 MPa), toughness, and extensibility (elongation at break: 1602%). Importantly, the hydrogen bond network enables efficient room-temperature self-healing, achieving 86.5% recovery after 15 h at 30°C. Furthermore, the synergistic utilization of petroleum-derived poly(ε-caprolactone) diol and bio-based castor oil provides tunable biodegradability, resulting in a weight loss of 4.56 wt.%–9.97 wt.% in a solution of lipase in phosphate-buffered saline after 4 weeks. Integrating high mechanical performance, self-healing capability, intrinsic fluorescence, and eco-degradability, WPU-AHHN demonstrates significant potential for emerging applications in optical anti-counterfeiting applications, flexible electronics, information encryption, and protective coatings.

Vibration and noise significantly compromise the service life of mechanical equipment. Damping materials are commonly employed to mitigate these detrimental effects. Extensive studies have demonstrated that viscoelastic polyurethane exhibits excellent comprehensive performance and facile modification capabilities. However, its practical application is limited by poor thermal stability and a narrow damping temperature range. The incorporation of nanofillers can further enhance these material properties. In this study, waterborne polyurethane-polyacrylate (WPUA) composites are synthesized, and the influence of nano-silica (SiO₂) and multiwalled carbon nanotubes (MWCNTs) on the properties of WPUA is investigated. The damping performance of materials is characterized by the loss factor (tan δ), effective damping temperature range (tan δ > 0.39), and curve integral area (TA). The results demonstrate that the addition of polyacrylate (PA) broadens the damping temperature range to 68°C due to differences in the glass transition temperature (T_g). Upon nanofiller incorporation, a physical cross-linking network maintains the tan δ value at 0.49 over a wide temperature range. The tensile strength exhibited a 40% increase compared to the WPUA materials, while the maximum contact angle reached 90.5°. Furthermore, the initial decomposition temperature of the composite increases significantly to 285°C, confirming the superior properties of the blend.

In this study, a prepreg system was developed using a water-based resol-type phenolic resin (PFR) reinforced with high silica fabric. Then, plates were produced from this prepreg material by the hand-laying method; the plates were cured in an autoclave environment, and an ablative composite material with high thermal resistance and low erosion rate was obtained. Thermal, mechanical, physical, and ablation tests were performed on the composite material, and the results were evaluated. Thermal expansion values were 5.12, 1.04, and 2.07 μm/m °C at the temperature ranges of 20°C–45°C, 80°C–105°C, and 130°C–180°C, respectively. The density of the produced thermoset composite material is about 1.8 g/cm³. The fiber ratio of the composite is about 69%. Thermal conductivity values were calculated from 30°C to 130°C, perpendicular and parallel to the fiber, and were found to be in the range of 0.0078–0.004 W/m K. This work provides information on the thermal protection systems, that is, the ablative materials with high silica fabric-reinforced resol resin prepregs.

Bilirubin is a potent endogenous antioxidant and anti-inflammatory molecule, but its therapeutic use is limited by poor solubility, instability, and cytotoxicity. To overcome these challenges, bilirubin-loaded bovine serum albumin nanoparticles (BSA-BRNPs) were prepared via an optimized desolvation method and characterized for their physicochemical, antioxidant, and anti-inflammatory properties. BSA-BRNPs exhibited a hydrodynamic diameter of 156.8 nm, a zeta potential of −23.1 mV, and a high encapsulation efficiency of 74.7%. The formulation enabled sustained bilirubin release (~74% over 96 h) and significantly reduced cytotoxicity in RAW 264.7 macrophages compared with free bilirubin. BSA-BRNPs also showed strong radical- and peroxide-scavenging activity in 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and ferric ion oxidation assays and markedly suppressed lipopolysaccharide/interferon-γ-induced nitric oxide and intracellular reactive oxygen species production. Collectively, these findings indicate that BSA-BRNPs enhance bilirubin stability, biocompatibility, and antioxidant performance, supporting their potential as a safe and efficient nanocarrier for oxidative stress-related inflammatory conditions.

Gelatin had been widely used in the fields of food, cosmetics, biomedicine, etc. However, bacterial infection remained a critical threat in these fields and had serious risks to human health and life. Unfortunately, gelatin lacked inherent antibacterial properties, which limited its broader applications. Although several strategies had been developed to synthesize modified gelatin with antibacterial properties, it was still a challenge to prepare antibacterial gelatin at low cost. In this work, the gelatin/ε-polylysine covalent conjugates were prepared through a facile ring-opening addition reaction employing ethylene glycol diglycidyl ether (EGDE) as a cross-linking reagent. The Fourier-transform infrared spectroscopy (FTIR), ¹H nuclear magnetic resonance (NMR) spectra, X-ray photoelectron spectroscopy (XPS), primary amino contents, amino acid analysis, molecular weight, zeta potential, viscosity, gel strength, melting/gelling temperatures, and dissolution time of the covalent conjugates were characterized. The products exhibited significant antibacterial activity, as confirmed by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. The cell counting kit-8 (CCK8), live/death staining, and hemolytic properties were studied in detail and the results showed that the gelatin/ε-polylysine covalent conjugates possessed favorable cytocompatibility. This approach avoided the use of expensive cross-linking reagents, thereby maintaining low production costs for the modified gelatin. The ring-opening addition reaction demonstrates potential as a universal and cost-effective method for preparing antibacterial gelatin derivatives.