Investigation of the liquid-liquid transition in atactic polystyrene by thermally stimulated depolarization current

Atactic polystyrene (aPS), which is a poor polar polymer, is one of the most important engineering materials. The multiple relaxation transitions of aPS have been studied by many researchers. It was reported that there are two or three relaxation peaks in the spectra of thermally stimulated depolarization current (TSDC) above room temperature [1-2]. However, the results did not agree well enough with each other, which might be attributed to the different sample or measuring process and method. It was found that there was an amorphous transition, designated as liquid-liquid transition (T_LL) in aPS at above T_g [2]. In this work, the relaxation and transition behaviors of aPS, especially liquid-liquid transition, above room temperature are investigated using TSDC in detail.