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.