Study of multiple relaxations in styrene-acrylonitrile copolymer using thermally stimulated current method

The dielectric behaviour and the electrical polarization in as-cast and polarized films of styrene-acrylonitrile (SAN) copolymer have been investigated using the Thermally Stimulated Current (TSC) technique. Films were polarized with various field strengths in the range 20 to 80 kV cm^?1. The TSC spectrum showed four peaks (at ～ 70, 105, 130 and ～ 180°); their origins are explained in terms of the relaxation of the nitrile side-groups, glass-transition of the copolymer and the space-charge displacement. Thermal peak-cleaning and partial-heating techniques were applied in order to determine the exact positions of the peaks and the activation energies associated with the processes.