ONSET OF THE FAST PROCESS IN AMORPHOUS POLYPROPYLENE AS DETECTED BY QUASI-ELASTIC NEUTRON-SCATTERING AND ELECTRON-SPIN-RESONANCE TECHNIQUES

Local chain dynamics of atactic polypropylene, a typical amorphous vin yl polymer, has been studied by both quasielastic neutron scattering a nd macroradical decay measurements by electron spin resonance to detec t the fast process of picosecond order observed for most amorphous mat erials. It was found that the fast process sets in at the Vogel-Fulche r temperature T-0, similar to observations for other simple polymers, suggesting that the fast process is a precursor of the glass transitio n. In coincidence with the onset of the fast process, the acceleration of the macroradical decay is also observed in the vicinity of T-0, in dicating a close connection of both phenomena. This is the first exper imental evidence for the fast process from two independent measurement s.