Photon correlation spectroscopy of poly(ethyl methacrylate) near the glass transition

Abstract

Poly(ethyl methacrylate) has been studied by photon correlation spectroscopy in the temperature range 70–150°C. The relaxation function for longitudinal density fluctuations is highly nonexpon-ential and changes shape dramatically as the sample is cooled. The results indicate that there are multiple relaxation processes which have different apparent activation energies. The average relaxation time changes by a decade with a 5°C change in temperature near T_g. The breadth of the distribution of relaxation times near the glass transition is at least eight decades.