Glass transition and thermal expansivity in silica-polystyrene nanocomposites

Abstract The glass transition temperature T g and the thermal expansion coefficient have been measured using the capacitive scanning dilatometry for silica-polystyrene (PS) nanocomposites with various silica volume fraction up to 50 vol.%. The glass transition temperatures for silica-PS nancomposites show a deviation from the bulk T g together with a large scatter. Thermal expansivity decreases with increasing silica fraction both below and above T g . A clear relaxation peak can be observed in the expansivity–temperature curve for silica-PS nanocomposites. The intensity of the peak decreases with increasing silica fraction. The decrement is larger than the value expected on the assumption that silica particles do not participate in the glass transition.