Effects of silane coupling agents on the electrical properties of silica/epoxy nanocomposites

Abstract

Effects of surface modification agents on the properties of silica (SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) /epoxy resin (EP) nanocomposites were studied for the significant impacts of the interface structure between the fillers and resin matrix. The surface modification agent of KH550, KH560 and KH570 were grafted to the surfaces of SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> fillers. The original and modified SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> fillers were characterized by FTIR and TG. Nanocomposite samples were prepared by solution blended process, using 0.3 wt% SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> as filler and epoxy resin as polymer matrix respectively. DSC analysis was performed to investigate the glass transition temperature (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ). Dielectric spectroscopy and breakdown tests were conducted to measure the dielectric permittivity, dielectric loss and breakdown strength. The results show that SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> can be grafted with KH550, KH560 and KH570 effectively. Compared with neat epoxy, the T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> and breakdown strength of nanocomposites increased. Influences on the dielectric permittivity were found, depending on the interface between SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> fillers and resin matrix. In terms of T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> , breakdown strength and dielectric loss, the KH550 and KH560 modified nanocomposites performed better than the KH570 modified nanocomposites, which is due to the amino and epoxy group on the molecular structure of KH550 and KH560 respectively. These chemical groups played positive roles in cross-linking reaction and building better interfaces for nanocomposites.