DEPOLARIZED RAYLEIGH SPECTROSCOPY OF POLYSTYRENE NEAR THE GLASS-RUBBER RELAXATION

Depolarized Rayleigh scattering in polystyrene near the glass-rubber relaxation is studied using photon correlation spectroscopy. The observed correlation functions cannot be fit to a single exponential decay, but the empirical form CH(t)-1 = δ + A exp[-2 (t/τ) β] describes the results very well. Average relaxation times 〈τ〉 = (τ/β)Γ(1/β) are determined from 100 to 130°C. The apparent activation energy for the change of 〈τ〉 with temperature is over 80 kcal/mole. Depolarized Rayleigh spectroscopy should prove to be a very useful tool in the study of relaxation behavior in polymers. © 1979 American Institute of Physics.