CARBON-CARBON TORSIONAL BARRIERS DRIVING THE FAST DYNAMICS IN GLASS-FORMING POLYMERS

By considering neutron-scattering data of 17 glass-forming polymers, a n experimental correlation is found between the temperature range T-f, at which the fast dynamics sets in, and the carbon-carbon torsional b arrier in the polymer chain. This model-independent result, which sugg ests an intramolecular interpretation of the fast dynamics in glass-fo rming polymers, is easily explained in the framework of a model which relates the fast dynamics to the short-time regime of the segmental dy namics (alpha relaxation).