Strain-induced softening of glassy and crystalline polymers

The data on strain-induced softening of glassy and crystalline polymers accompanying by development of capability of the deformed samples to high reversible strains are analysed. It is shown that in the first deformation cycle, the test sample demonstrates properties typical of glassy or crystalline state, whereas at the repeated stretching, it undergoes transformation into a rubber-like high-elasticity state, in which the polymer is capable of high reversible strains. It is noted that this transition represents a physical basis of strain-induced softening of glassy and crystalline polymers.
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