Investigation on the preparation and properties of low-dielectric ethylene-vinyl acetate rubber / mesoporous silica composites

Mesoporous silica (SBA-15) was synthesized and two kinds of silane coupling agents, Triethoxyvinylsilane (A-151) and 3-Aminopropyltriethoxysilane (KH-550), were used to surface-modify SBA-15. Modified SBA-15 (M-SBA-15) maintained original well-ordered hexagonal structure of SBA-15. A series of ethylene-vinyl acetate rubber (EVM)/ M-SBA-15 composites were prepared. The morphologies, dielectric properties, dynamic mechanical properties and thermal stability of the composites were investigated. Dielectric constant of the composites could be significantly reduced from 6.6 of the pure EVM to 4.8 and 5.0 by loading 0.5 phr SBA-15 modified with A-151 (AM-SBA-15) and 0.5 phr SBA-15 modified with KH-550 (KM-SBA-15) respectively. The dielectric constant and dielectric loss of the composites also showed scarcely frequency and temperature dependence over a wide scope. Improved dynamic mechanical properties and thermal stability of composites were observed.