Chunyue Ma, Ran Zhao, Dongzhi Wang
ABSTRACT Spherical silica micropowder (SSP) features excellent fluidity, thermal conductivity, and chemical stability, making it widely used in fields such as aerospace. However, when used as an inorganic filler mixed with organic matrices, silica micropowder still faces problems of poor compatibility and difficult dispersion. To address the issue of poor interfacial compatibility in composite materials, this study employed silane coupling agent (SCA) 3‐glycidyloxypropyl trimethoxysilane (GPTMS) and 3‐methacryloxypropyl trimethoxysilane (MAPTMS) to modify the surface of silica powder, which was then introduced into the epoxy resin (EP) matrix as a functional filler. The results show that the silica micropowder modified by SCA can not only improve its compatibility in epoxy resin but also enhance the thermal conductivity and mechanical properties of the composite materials. X‐ray photoelectron spectroscopy (XPS) confirms the successful grafting of SCA onto the silica surface. After preparing the composite with the modified silica powder, comprehensive tests and analyses were conducted on its viscosity behavior, thermal stability (TG), thermal conductivity, and mechanical properties. The experimental results demonstrate that silica powder modified with GPTMS and MAPTMS effectively improves the thermal conductivity of the composite while significantly enhancing its mechanical performance. This study provides important experimental evidence and theoretical references for the development of high‐performance epoxy molding compounds.