Journal of Applied Polymer Science最新文献

Phase change materials (PCMs) have attracted considerable attention for their energy storage and thermal regulation properties. However, the solid–liquid leakage, low thermal conductivity, and single functionality of PCM composites hindered their applications, especially. In this paper, the phase change composite fibrous membranes with highly efficient thermal management ability are prepared by coaxial electrospinning technology with polyethylene glycol (PEG) as the PCM in the core layer and polyamide 6 (PA6) as the supporting materials. Convenient impregnation, a method with cesium-tungsten bronze (Cs_0.32WO₃, CWO) dispersion, was applied to integrate the infrared shielding agents into the shell. The prepared PEG/CWO/PA6 membranes exhibited a high thermal enthalpy of 92.04 J/g with a loading rate of 63.8%. PEG was well encapsulated in the fibers and maintained stability after 50 thermal cycles, with only 5.6% loss of heat latent and no obvious leakage. The synergistic effect of PCMs and infrared shielding agents ensured the application in thermal management, with an obvious decrease in temperature of about 2.8°C, especially under infrared irradiation. The phase change composite fibrous membranes synergistically fabricated with infrared shielding materials are controllable and anticipated to be highly potential materials for thermal control and temperature modulation in electronic and intelligent devices.

The effects of cooling rate and molecular weight on the nonisothermal crystallization behavior of polyethylene were investigated. In systems with slower cooling rates, chains exhibit greater mobility and have sufficient time to transition from cis to trans conformations. The average length of the trans chain is also larger, and there are fewer entanglements, which facilitate the crystallization. The coupling effect between segmental conformation transition and local segmental orientation and their relationship with nucleation was examined, revealing that nucleation occurs predominantly in regions with a high concentration of conformationally ordered chain segments. As the cooling rate increases, the proportion of conformationally ordered segments decreases. Additionally, in systems with higher molecular weight, there are more entanglement points, leading to reduced segment mobility, which hinders conformational transitions and ordered arrangements. This structure results in increased conformational entropy and reduced nucleation capability. At the early stages of crystallization, the nucleation mechanism of molecular chains is primarily characterized by intramolecular chain folding. Systems with higher molecular weights contain more chain-folded atoms.

Strain sensor, valued for their elasticity and versatility, have gained significant attention for application in human and robotics monitoring. Here, the flexible strain composite sensor fabrication process uses a dual extruder FDM 3D printer with thermoplastic polyurethane (TPU) and electric-conductive thermoplastic polyurethane (E-TPU) filament material, which consists of a “flat flexible covering” of pure TPU and a “mesh sensor component” of conductive TPU. The research prioritized design, fabrication, strain-sensing behaviors, and deformation of the TPU/E-TPU-made composite flexible strain sensors. As a result, the flexible composite sensors achieve significantly enhanced performance, 250% stretchability, exceptional sensing ability (compression, bending, and twisting), and durability under various deformations. The strain rate at 50, 70, and 100 mm/min affects the stress at break point (13.5, 16.4, and 25.5 MPa), strain at break (310%, 300%, 290%), and strain at yield point (9%, 12%, and 13%), respectively. Carbon (35% atomic C, 33% weight C) have exceptional mechanical properties, comprising strength, stability, and toughness, per SEM-EDS and microstructural investigations. The flexible strain composite sensors indicate significant potential for practical wearable and soft robotics applications after real-time testing.

The use of biopolymer-based hydrogels represents a promising alternative for achieving controlled drug release. In this study, poly(γ-glutamic acid) hydrogels loaded with neomycin sulfate were obtained. Characterization of drug-loaded hydrogels was conducted using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Thermogravimetric Analysis (TGA), confirming the presence of the drug within the polymer matrix and elucidating interactions between neomycin sulfate and polymer chains. The controlled release of neomycin sulfate was evaluated under various pH and temperature conditions. Data fitting the Korsmeyer-Peppas model indicated an “anomalous” diffusion process. Cytotoxicity tests on the L929 cell line revealed biocompatibility at concentrations of 3.125, 6.250, 12.5, and 25 mg/mL. Therefore, this work indicates that poly(γ-glutamic acid)-based hydrogels are biocompatible and highly effective for controlled drug release.

This study presents an approach to enhancing dielectric properties, energy storage performance, and thermal stability of polymer composite. A dielectric composite film based on polyarylene ether nitrile (PEN) was prepared, in which SiC acted as fillers. PEI and PDA layers were co-deposited on the surface of SiC particles to improve the dispersion of the SiC filler in the PEN resin. Benefiting from SiC's thermal stability and rigidity, the composites exhibit good thermal conductivity and low coefficient of thermal expansion. Besides, the introduction of SiC@PDA-PEI enables the composite film to have superior electrical insulation, with a breakdown field strength of up to 195 kV/mm, 63.9% higher than that of pure PEN film. Moreover, the dielectric constant of composite films increased from 3.3 to 5.0 as the PEN/SiC@PDA-PEI addition content increased, resulting in a significant increase in the energy storage density of the composite films. When the PEN/SiC@PDA-PEI addition content was 2 wt%, the energy storage density of the composite film was 233% higher than pure PEN film. Therefore, this multifunctional composite film shows broad application potential in electronics, aerospace, and high-end manufacturing fields.

Polylactic acid (PLA) exhibits excellent biocompatibility and degradability but suffers from brittleness, low toughness, and flammability. In this study, a novel one-dimensional magnesium-based inorganic/organic hybrid flame retardant filler was synthesized by grafting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) onto magnesium sulfate (MOS) whiskers modified with vinyltrimethoxysilane (VTMS), which can be melt-blended into PLA to enhance its flame retardancy and mechanical properties. This article uses x-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), thermogravimetric analysis-derivative thermogravimetry (TG-DTG), and mechanical analysis. The flame retardancy of PLA significantly improves with the increase of DOPO-MOS/PLA filler content, and its combustion grade increases from FH-3 to FH-1, while the melt dripping decreases. Carbon layer analysis indicates that the flame retardant effect is attributed to condensation and gas-phase suppression. At a lower addition level, specifically when the amount is 2 parts per hundred resin weight (phr), the optimal impact strength reaches 8.22 kJ/m², and the optimal bending strength reaches 10.91 MPa. Furthermore, the whiskers increased the crystallinity of PLA, reaching a maximum relative crystallinity of 35.23%. This article provides a reference for exploring new organic/inorganic flame retardant additives.

In this study, bioreduction methods for the synthesis of silver nanoparticles (AgNPs) have been used to provide a sustainable, environmentally friendly, and cost-effective solution. The current work shows that soluble starch, maize starch, and rice extract can be utilized as stabilizing as well as reducing agents for AgNP synthesis. The resulting stabilized AgNPs ranged in size from 10 to 30 nm. Transmission electron microscopy, UV–visible spectrophotometry, and XRD analysis have been used to characterize the size, shape, and structure of the nanoparticles. For biosynthesized AgNPs, UV–visible spectroscopy revealed a surface plasmon resonance peak at 410–420 nm. Analysis of transmission electron microscope images confirms the synthesized AgNPs have a quasi-spherical shape and uniform surface morphology with a size range from 10 to 30 nm. The cotton substrate was then allowed to get finished with these biosynthesized AgNPs using the pad-dry-cure technique, and their antibacterial and antiviral activity was evaluated using the AATCC 100 and ISO 18184 methods, respectively. Wash durability for antibacterial properties has been carried out for the AgNP-finished fabrics, up to 50 washes. The developed AgNP-finished fabric revealed excellent antimicrobial and wash-resistance properties.

In response to the urgent demand for sustainable energy storage technologies and the reduction of environmental contamination from fossil fuels, supercapacitors are recognized as a viable technological advancement. They are distinguished by their superior power density and exceptional stability over numerous cycles. However, their energy density is still rather low compared to other available options, and this is a significant deterrent to their use. Some of the recent works have shown that integrating electric double-layer capacitance with pseudo-capacitance can greatly improve the energy density of such systems. To this end, the hypercrosslinked polynaphthalene-based polymer was used to synthesize the microporous carbon through the process of chemical activation, and the material was named MONC-800-2. Then, cobalt acetylacetonate was used to introduce Co into the carbon matrix using the hydrothermal method to synthesize Co-doped hypercrosslinked polynaphthalene-based microporous carbon, namely MONC-800-2@Co-1-190. This material was revealed to have high microporosity and proper pore size distribution. The integration of cobalt within the electrode material of supercapacitors successfully combines the features of electric double-layer capacitors and pseudo-capacitive mechanisms, yielding a specific capacitance of 363.8 F g⁻¹ at a charging current density of 1.0 A g⁻¹. Employed within a hybrid supercapacitor system, this setup achieved an energy density of 16.13 Wh kg⁻¹ and a power density of 750 W kg⁻¹. After enduring 5000 charge–discharge cycles under a steady current, the system preserved 82.85% of its initial capacitance while maintaining a coulombic efficiency of approximately 99.99%, thereby demonstrating its excellent cycling stability and high coulombic efficiency. The developed work is significant in advancing the metal-doped microporous carbon materials for the improvement of supercapacitors.

Fe-based metal organic framework was used to load macroporous resin by repurposing waste polyethylene terephthalate for congo red removal. Fe-based metal organic framework/resin was systematically analyzed and various adsorption factors were optimized. Adsorption mechanisms were investigated based on kinetics, isotherms, thermodynamics, and various instruments. The pseudo-second-order (R ² > 0.997) and Langmuir model (R ² > 0.987) suggest that the adsorption process followed a homogeneous monomolecular layer and chemisorption. The thermodynamic analysis indicated that the adsorption was spontaneous and endothermic. At pH = 7, the maximum adsorption capacity was 766 mg/g. In addition, Fe-based metal organic framework/resin exhibited a favorable adsorption selectivity towards congo red with Cl⁻, SO₄,²⁻ and CO₃ ²⁻. It could be conveniently separated and reused. With the help of density functional theory calculations, analyze the adsorption mechanism in depth. Adsorption mechanisms were pore filling, electrostatic interactions, π–π stacking, and hydrogen bonding. Thus, polyethylene terephthalate-derived adsorbents could be well applied to water purification, environmental protection, and separation processes.

The wetting phenomenon is an undesirable characteristic of membrane contactors utilized for gas absorption applications. In this research, polysulfone hollow fibers (PSF) modified by silicone rubber coating (PDMS) loaded with hydrophobic silica nanoparticles (SiO₂) were studied as membrane contactors in order to dehumidify the feed gas using diethylene glycol (DEG) as the sorbent liquid. The study aimed to evaluate how the addition of nanoparticles influenced the membrane's structure, hydrophobicity, roughness, and separation performance, particularly flux and efficiency. Findings revealed that surface modification raised the contact angle pressure of water and DEG from 72° to 154° and 58° to 127°, respectively, and enhanced the liquid entry pressure of water and DEG from 6.1 to > 10 bar and 3.7 to 6 bar, respectively. The effect of liquid velocity on water vapor absorption flux was minimal, indicating no mass transfer resistance in the liquid phase. However, increased gas phase velocity significantly improved absorption flux and efficiency. Initially, the neat membrane had a higher absorption flux due to its effective porosity, but its performance dropped over time, failing by day 20. The results of the stability test demonstrated that a wetting ratio ranging from 1% to 2%, achieved after 11 to 16 days, led to a reduction in flux by 30% to 55%. Conversely, the optimum silicone rubber-coated membrane loaded with silica nanoparticles maintained a wetting ratio under 1% and showed more stable flux with respect to the reference membrane for 42 days (a 6 weeks test) due to enhanced surface characteristics. The optimum membrane depicted a flux of 1.8 × 10⁻² mol/m² s, which is 1 to 2 orders of magnitude higher than the previous studies. It was anticipated that, by modifying the surface properties of the contact membrane, the long-term performance of the contact membrane would be enhanced to have a significant growth compared to the pure membrane and the open literature reports. The results show that the applied technique for fabricating hollow fiber membrane contactors can be a promising technique in gas conditioning processes.