Fabrication of thermal conductivity enhanced polymer composites with three-dimensional networks based on natural cotton

Functional fillers prepared by facile natural materials have attracted much attention for their superior engineering performances and promise to replace the traditional, expensive, and environmentally unfriendly fillers. Herein, carbon fiber aerogel (CFA) was prepared by an annealing process of natural cotton. Silicon carbide (SiC)@CFA with antihygroscopic and thermal stability was further obtained by in-situ growth via template-assisted chemical vapor deposition method. After that, CFA/Epoxy composites and SiC@CFA/Epoxy composites with enhanced thermal conductivity at low-loading fraction were prepared by vacuum-assisted impregnation of epoxy resin. The SiC@CFA/Epoxy composites have higher thermal conductivity (0.404 W/[m center dot K] at 1.85 wt% filler at room temperature), higher resistivity, smaller coefficient of thermal expansion, and higher glass transition temperature than CFA/Epoxy composites. Furthermore, the thermal conductivity of the pure epoxy resin and the composites were tested from 150 to 370 K, and the ratio of the thermal conductivity of the composites to that of the pure epoxy resin is greater at low temperatures than at room temperature.