Molecular mobility and radiation-induced transformations of polytetrafluorothylene

Results of acoustic studies of molecular mobility and radiation-induced transformations in polytetrafluoroethylene (PTFE) are presented. Dynamic modulus, mechanical losses and low-frequency sound velocity (viscoelastic characteristics) are studied as characteristics of molecular mobility. Irradiation of samples by low doses of γ-quanta, at the absorbed dose rate P=0.8 Gy/s, and accelerated electrons (P=16 Gy/s) is carried out both in the vacuum and in the air. Viscoelastic characteristics of samples with different degree of crystallinity are investigated at the frequencies of flexural vibrations ranging from 5 to 2000 Hz in the 95-650 K temperature ranqe. Crystallinity degree is measured using the methods of density determination and DTA. The results are presented in graphic form