Key Words:polystyrene; TiO2; nanocomposites; dilatometry; glass transition; free volume
Abstract:The glass transition and free volume of high impact polystyrene (HIPS)/TiO2 nanocomposites are investigated by dilatometry, along with the influence of free volume variation on rheological behavior and deformation temperature. Transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FE-SEM) show the presence of monodispersed nanoparticles and small agglomerated particles. The glass transition temperature (T-g) of nanocomposites containing 1-3% TiO2 is slightly lower than that of HIPS. The enhanced segmental motion of HIPS molecules located in the interface region results in the occurrence of extra free volume and the depression of T-g. The thermal expansion coefficient of HIPS increases with increasing TiO2 content and is obviously higher that of the free volume in the nanocomposites. Furthermore, the abnormal variation in rheological behavior and deformation temperature is consistent with the increase of free volume.
Volume:45
Issue:5
Translation or Not:no