Dielectric relaxation spectroscopy in high-impact polystyrene/titanium-dioxide composite films

Abstract

The relaxation processes in high-impact polystyrene (HIPS) free-standing films filled with titanium dioxide (TiO2) of the rutile modification were investigated by means of dielectric relaxation spectroscopy (DRS) supplemented by differential scanning calorimetry (DSC). Films with 2, 4, 6 and 8 vol.% TiO2 are compared to each other and to non-filled samples. Above the glass transition one relaxation becomes visible for unfilled HIPS. It can be identified as the α relaxation, related to the onset of micro-Brownian motions at the glass transition. The low-frequency (LF) process (which superimposes with α relaxation near Tg) is observed on all TiO2 containing films. The LF process for composite films is not uniform and shows Arrhenius behavior. At lower temperatures (up to about 130 °C) an activation energy of 1.1 eV is found, whereas in the limit of high temperatures, and particularly for higher TiO2 content the activation energy is 2.4 eV

Keywords

• dielectric spectroscopy
• high-impact polystyrene
• titanium-dioxide
• composite films