Accumulation of submicroscopic defects in fluoroplastics during their viscous fracture

The character of the accumulation of submicrocracks in fluoroplastics 4, 4D, and 4DM during a moderate-duration cold stretching was studied by x-ray diffraction patterns and mechanical methods. It was shown that during viscous fracture of fluoroplastics, an active accumulation of submicrodefects takes place, which substantially depends on the previous thermal history of the samples. Irreversible submicrofractures accumulate in annealed samples not only at the opening of the main crack, but also throughout the entire volume of the sample. Qualitative correlations have been established between the crystallinity and the concentration of the submicrocracks, on the one hand, and the yield point and the ultimate strength of the polymers, on the other. The degree of damage before the fracture of the fluoroplastic samples was evaluated phenomenologically.