Nanoporous SiO2 grafted aramid fibers with low thermal conductivity

Silica aerogel is an excellent thermal insulation material for its mesoporous nanostructures In this study, the aramid fibers were grafted with the mesoporous structure of silica aerogel to reduce the fiber thermal conductivity through a serious process. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results indicate that siloxane groups were successfully grafted onto the fiber surface through nitration , reduction and grafting with 3-glycidoxypropyltrimethoxysilane (GPTMS). After cohydrolysis with tetraethyl orthosilicate (TEOS), condensation, alkylation and ambient drying, SEM images of the as-prepared fibers showed that a mesoporous structure formed around the fiber surface. Si content within the as-prepared fiber was about 10.5 times higher than the fiber grafted with GPTMS. The fiber was covered with a mesoporous and hyperbranched network. As a result, the thermal conductivity of blanket consisting of the as-prepared aramid fibers, measured by transient hot-wire method, was obviously lower than that of the original ones, whereas the thermal stability changes little.