FREE-VOLUME AND MICROSCOPIC DYNAMICS IN AMORPHOUS POLYMERS

The free-volume microstructure in three amorphous polymers cis-1, 4-po lybutadiene (PBD), polyisobutylene (PIE) and atactic polypropylene (a- PP) has been studied by positron annihilation spectroscopy via the ann ihilation characteristics of ortho-positronium, lifetime tau(3) and re lative intensity I-3. Simultaneously, the local chain dynamics has bee n studied by neutron scattering. The temperature coefficients of hole size below and above T-g are comparable with those of mean-square disp lacements indicating that the free-volume hole expansion is governed b y the microscopic chain mobility. In addition, the relative intensity anomalies in simple polymers (PBD, PIE) are related to the onset of th e fast process. This is a structural indicator for the course of fast process.