Investigation of the influences of the molecular weights and dosage ratios of polyvinyl alcohol on para‐aramid nanofibers/polyvinyl alcohol composite aerogels

Abstract

Polymer-based monolithic composite aerogels with a durable cross-linked structure were fabricated using polyvinyl alcohol (PVA) and para-aramid nanofibers (ANFs) as precursors, and supercritical fluid technology as a drying strategy. In order to give a clear insight into ANFs/PVA composite aerogels, we thoroughly investigated the influences of the molecular weights and dosage ratios of PVA on these composite aerogels, and clearly demonstrated the entire process of the evolution of "sol-gel-aerogel." The chemical composition, porous nanostructure, porosity, and mechanical performance of the ANFs/ PVA composite aerogels were characterized by attenuated total reflectance-Fourier transform-infrared spectra (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FE-SEM), nitrogen physical adsorption, and uniaxial compression, respectively. The results revealed the mechanism of the stable composition of ANFs/PVA binary system, and that both the molecular weights and dosage ratios of PVA in the ANFs/PVA composite aerogels have a significant influence on their properties. This work is beneficial to design and fabricate polymer-based aerogels with desirable chemical and physical characteristics, and the obtained ANFs/PVA composite aerogels with appropriate molecular weight and dosage ratio of PVA possess well-balanced comprehensive properties, which offer the potential for a wide range of applications.

Enhanced In-Plane Thermal Conductivity and Mechanical Strength of Flexible Films by Aligning and Interconnecting Si3N4 Nanowires

“…In comparison, the Si–N transmission intensity of the modified film was reduced, mainly due to the SA coating absorbed on the surface. In addition, the modified film exhibited more FTIR characteristic peaks of −CH 3 , −CH 2 –, CO and C–O, and −OH groups, − strongly indicating that SA had been successfully encapsulated on the surface of the composite film. The microscopic morphology of the modified composite film surface is shown in Figure S6b.…”

‘Rigid‐soft’ synergistic effects to improve the microstructure and superflexibility properties of aramid nanofiber aerogel

“…Nevertheless, with the increase of heating time, the temperature of sample thermal infrared imaging tends to rise. Its thermal insulation effect is slightly reduced with the increased CNF/PVA, which is closely related to the pore structure 25,26 . Compared with ANF aerogel, the pore structure of composite aerogel has better thermal insulation performance and good heat resistance due to the joint action of flexible PVA and semi‐rigid CNF.…”

Synchronous Radiative Cooling and Thermal Insulation in SiO2/Poly(vinyl alcohol) Composite Aerogel for Energy Savings in Building Thermal Management

“…The molecular weight of PVA has great effect on its solubility, thermal stability, and mechanical and hydrolytic properties. Higher molecular weight PVA has good thermal stability and mechanical properties, , therefore PVA with a polymerization degree of 1750 was adopted in SiO 2 /PVA composite aerogel. In the fabrication, the SiO 2 /PVA composite dispersion in a mold was frozen at a low temperature of −70 °C, in which phase separation and crystallization of PVA occurred because acetone is a nonsolvent for PVA and has a lower crystallization temperature than water.…”