AC breakdown strength and glass transition temperature of mesoporous silica/EP composite

Epoxy (EP) and EP-based composites are used as insulating materials in several electrical applications. In this work, the mesoporous silica-epoxy (SBA-15/EP) nanocomposite was prepared after surface modification of SBA-15 with a silane coupling agent KH550. Then, SBA-15/EP composite with different weight percentage of SBA-15 was prepared by using the in situ polymerization. Transmission electron microscopy of ultrathin section of the nanocomposites confirmed that some EP molecules were introduced into and partly occupying the nanopores in SBA-15. Subsequently, the dynamic thermomechanical analysis and AC breakdown were employed to research the glass transition and electric property of nanocomposite. Moreover, the dielectric property and space charge of the SBA-15/EP composites was investigated. And the effect of nanopores on the property of composite was discussed. The results confirmed that the glass transition temperature and electrical breakdown strength of the nanocomposite were significantly improved at a low SBA-15 content while the dielectric and space charge property remained comparable with that of pure EP.