Effect of pressure on the dielectric ?-relaxation in polyethylene terephthalate

Abstract

The dielectric β relaxation in amorphous polyethylene terephthalate has been studied over a range of frequency, temperature and applied hydrostatic pressure. The results are discussed in terms of available models for relaxation in the glassy state. None of the available models satisfactorily accounts for the experimental data, and a new model based on relaxation over a barrier involving coupled motions of the chain is proposed in a qualitative manner.