Abstract
Temperature dependent measurements of ^13^C spin lattice relaxation times and of nuclear Overhauser enhancement factors were carried out for atactic and isotactic polystyrene in tetrahydrofuran and for atactic polystyrene in 1,4‐dioxane. The analysis of the relaxation data by means of a Cole‐Cole distribution of correlation times confirms the additivity of intramolecular and solvent viscosity dependent activation energies. For atactic and isotactic polystyrene the same intramolecular activation energy of 21 ± 5kJ/mol is obtained for the segmental motion. A comparison with ^13^C relaxation measurements of other authors shows that the intramolecular activation energies and the anisotropy of the segmental motion are increasing simultaneously by changing the solvent from toluene over pentachloroethane to tetrahydrofuran. Based on the experimental findings the chain motions in polystyrene are interpreted as diffusion controlled processes in the hindering potential of the CC bonds of the chain backbone which is modified by conformation dependent interactions between phenyl groups and solvent molecules.