Journal of Applied Polymer Science最新文献

Proton exchange membranes (PEMs) in direct methanol fuel cells (DMFCs) transport protons while minimizing fuel crossover. However, commercial Nafion membranes face durability and methanol permeability issues. This study introduces a novel self-healable mesoporous silica (MSN) modified sulfonated poly(ether ketone) (SPEEK)/polyvinyl alcohol (PVA) membrane to improve DMFC efficiency and longevity. The composite membrane comprising 3 wt% MSN (S/PVA/MSN3) shows proton conductivity comparable to the pristine SPEEK, despite the inclusion of non-conductive PVA. MSN's large specific surface area and high porosity enhance water retention and facilitate proton transport. The methanol permeability of S/PVA/MSN3 is reduced by 29% compared to the pristine SPEEK, attributed to the combined effect of PVA's superior selectivity for water over methanol and the tortuous pathways created by MSN. Thanks to its improved selectivity, a DMFC with S/PVA/MSN3 achieves a remarkable open-circuit voltage (OCV) of 0.63 V, even with a high methanol concentration of 8 M, and a peak power density of 8.79 mW cm⁻², which is 2.13 times greater than the commercial Nafion 117. Moreover, S/PVA/MSN3 demonstrates significant recoveries of 91% in OCV and 87% in maximum power output following damage and self-healing. These findings suggest that the self-healable S/PVA/MSN has the potential for future use in DMFCs.

More and more focus nowadays is laid on renewable “green” and smart materials. In this work, we want to demonstrate the multifunctional properties of cellulose (CE) with multiwall carbon nanotubes (MWCNTs) fiber (50 wt.% multiwall carbon nanotubes). Linear actuation of CE-MWCNTs fiber at the potential range 0.7 to −0.2 V in different solvents with the same concentration of bis(trifluoromethane) sulfonimide lithium salt (LiTFSI) revealed that the polar aprotic solvents propylene carbonate (PC), acetonitrile (ACN), and dimethyl sulfoxide (DMSO) had the main expansion at discharging. The main expansion occurred at charging in polar protic solvents such as water (Aq) and ethylene glycol (EG). Chronopotentiometric measurements of CE-MWCNTs fiber were performed and showed the best specific capacitance in PC solvent of 102.7 mF cm⁻² (±0.082 mA cm⁻²) with specific capacity retention of 83% (±3.82 mA cm⁻²). The sensor calibration revealed that the four different solvents can be distinguished. Characterization of CE-MWCNTs fiber is performed in scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) spectroscopy was performed to investigate the element content after actuation cycles. Raman and FTIR spectroscopy are conducted to evaluate the composition of fiber CE-MWCNTs.

Designing multifunctional composites with high flame retardancy and excellent electromagnetic shielding performance is of significant importance. In order to address the poor flame retardant and electromagnetic shielding performances of thermoplastic polyurethane (TPU) composites, in this work, the γ-propyl-trimethoxysilane (KH550) functionalized silicon microencapsulated ammonium polyphosphate (SiAPP-NH₂) was synthesized using interface modulation technology. Then, SiAPP-NH₂ was combined with a copper metal–organic framework (MOF-Cu) through microencapsulation and electrostatic self-assembly techniques to prepare microencapsulated flame retardants (SiAPP-NH₂@MOF-Cu). Subsequently, TPU composites were prepared through melt blending of SiAPP-NH₂@MOF-Cu with TPU material. The results showed that the interface interaction between SiAPP-NH₂@MOF-Cu and the TPU matrix was significantly enhanced. Compared to pure TPU, TPU/5SAN@1MC composite exhibited decreases of 78.7%, 51.3%, 59.3%, and 58.7% in peak heat release rate, total heat release, total smoke release, and total carbon dioxide release, respectively. In addition, TPU/1SAN@1MC/rGO composite achieved an average shielding effectiveness of 13.82 dB in the X-band, enabling its broad commercial application. This study offers a promising strategy for the fabrication of TPU composites with good flame retardant and electromagnetic shielding properties.

Multilayer packaging is commonly used in the food industry to improve product preservation by combining materials with specific properties for optimal protection. Ethylene vinyl alcohol (EVOH) is highly valued for its barrier properties against air and moisture. The mechanical properties of EVOH films are influenced by both the ethylene content, which affects crystallinity and barrier performance, and the thickness of the EVOH layer, which affects the film's mechanical strength. This study develops mathematical models to explore the relationship between EVOH film thickness, ethylene content, and mechanical properties, such as tensile strength, elongation at break, and elastic modulus. Using RSM with I-optimal design, the optimal conditions for EVOH films are identified at a thickness of 0.03 mm and 48 mol% ethylene content. The model predicts values of 25.178% for elongation at break, 3077.865 MPa for elastic modulus, and 97.444 MPa for tensile strength. These predictions are validated through ANOVA, confirming the statistical significance of the model. Experimental results show achieved values of 27.119% for elongation, 3437.811 MPa for elastic modulus, and 107.308 MPa for tensile strength, demonstrating model accuracy. To further validate these findings, EVOH films are characterized by SEM, FTIR spectroscopy, and TGA, providing valuable insights into the structural and functional properties for food packaging.

In recent years, heavy metal ion pollution issues occur frequently, and the prevention and control of heavy metal pollution have become an urgent environmental problem for human beings. To reduce the harm caused by heavy metal ion pollution, γ-Al₂O₃/polyvinylidene fluoride (γ-Al₂O₃/PVDF) composite membranes were prepared by electrospinning technology. The microstructures, phase structures, mechanical properties, and adsorption properties of the composite membrane were characterized by SEM, XRD, universal testing machine, and spectrophotometer. The results showed that the γ-Al₂O₃/PVDF composite fibers were randomly deposited, and the diameter of the fibers varied from 1.65 to 2.35 μm. The three-dimensional network structures were formed and the porosity was as high as 85.28%. When the content of γ-Al₂O₃ was 4%, the tensile strength of γ-Al₂O₃/PVDF composite membrane was the highest, which was 11.33 MPa. When the content of γ-Al₂O₃ was 6%, the adsorption capacity of γ-Al₂O₃/PVDF composite membrane on Cu²⁺ was the maximum. After adsorption, the adsorption capacity was 152.65 mg/g. The pseudo-second-order adsorption kinetics equation was suitable for describing the adsorption process; it meant that the adsorption process might be a chemical adsorption. These findings suggest that the γ-Al₂O₃/PVDF composite membranes have great potential in the application of water treatment.

To improve the performance of epoxy resin (EP), this study selected hexamethylene diisocyanate trimer (HDI trimer) and polypropylene glycol (PPG1000) as the main raw materials. Through a simple addition reaction, a terminal isocyanate group (NCO) polyurethane prepolymer (PUP) was successfully synthesized. A grafting reaction with EP was then carried out to prepare a series of epoxy resin grafted interpenetrating polymer network (IPN) polymers (EP-PUP-n) modified by the polyurethane prepolymer. The effect of PUP on the material properties was investigated. According to the results of mechanical performance tests, when the PUP content reached 20 phr, the impact strength and elongation at break of the EP-PUP-20 material increased by 128.1% and 43.1%, respectively, compared to pure EP material. Meanwhile, its tensile strength and bending strength remained at levels of 68.8 and 102.3 MPa, respectively. Thermogravimetric analysis shows that PUP-EP-n has excellent thermal stability. This opens up new avenues for the use of epoxy resins in various fields.

Four biochars were prepared from lychee shell with or without phosphoric acid activation under one- or two-stage heating, and characterized by scanning electron microscopy, transmission electron microscopy, infrared spectroscopy and Raman spectroscopy, respectively. Their adsorption capacities were evaluated by methylene blue adsorption test. Their electrochemical properties were depicted by electrochemical impedance spectroscopy and cyclic voltammetry. The biochar prepared by two-stage heating and phosphoric acid activation (LSC-THP) exhibited a high porosity, the best adsorption capacity, lowest electric resistance and largest electrochemically active surface, was applied to modify a glassy carbon electrode (GCE) after mixed with chitosan (CS), to fabricate the sensing electrode LSC-THP/CS/GCE for the simultaneous detection of catechol (CC) and hydroquinone (HQ). Square wave voltammetry and differential pulse voltammetry measurements indicated that LSC-THP/CS/GCE exhibited the best response current signal at pH 6.6, with the linear detection range of 10–2000 μmol·L⁻¹ and limit of detections of 1.23 and 0.44 μmol·L⁻¹ for CC and HQ detections, respectively. LSC-THP/CS/GCE also exhibited a good anti-interference ability and could be applied to the simultaneous detection of CC and HQ in real samples. This study provides a promising approach to improve the electrochemical performance of biochars for the development of novel electrochemical sensors.

Glyoxal dehydration and reinforcement are among the most widely used methods for treating water-saturated wood lacquerware in China. Ultraviolet (UV) light has a significant impact on the structure and properties of glyoxal polymers, which in turn can affect cultural relics treated with the glyoxal method. Therefore, in this study, a degradation experiment of glyoxal polymer was carried out under UV light irradiation at a wavelength of 351 nm. Fourier transform infrared spectroscopy, scanning electron microscopy, and differential scanning calorimetry were then performed on the samples after the test. Characterization tests, including calorimetry, were used to evaluate the effect of UV light on glyoxal polymers. After UV light irradiation, the surface color of the glyoxal polymer first brightens, then gradually darkens. The surface appears convex or even cracked; the overall shape gradually expands, and the volume increases significantly, but the mass gradually decreases. The analysis results show that after UV light irradiation, the glyoxal polymer chain breaks down, the glass transition phenomenon gradually disappears, and the decomposition temperature decreases. Photoaging occurs on the surface of the glyoxal polymer, leading to the formation of carbonyl groups (C=O) and an increase in cyano groups (–C≡N).

Thermoplastic thermal insulation materials (TTIMs) in high-rise buildings are often exposed to ultraviolet radiation, different temperatures, and humidity environments, leading to light aging. Their performances, such as surface color and morphology, have changed, whereas their fire risk has not been reported. Especially, the fire hazard of TTIMs is always an essential issue for high-rise building fires. Therefore, it is necessary to study the fire risk of aging TTIMs. An accelerated aging experiment of expanded polystyrene (EPS) was performed. Subsequently, downward and upward flame spread experiments were conducted to analyze the appearance properties of EPS, flame temperature, mass loss rate, and flame spread rate at different light aging stages. Finally, based on the laws of energy conservation and mass conservation, two models were established to characterize the flame spread rates of downward and upward flame spread. The results showed that light aging led to morphology changes in EPS, such as yellowing of color and structural damage. Aging increased the values of multiple parameters such as flame temperatures, mass loss, and flame spread rate, indicating that light aging increased the fire risk. Especially, the models indicated that the flame spread rate had a nonlinear relationship with flame temperature and pyrolysis temperature.