The effect of thermal prehistory on relaxation mechanical and dielectrical properties of rubberlike polymers has been studied by varying the conditions of heating and cooling of the specimens. The annealing of specimens by slowly cooling heated specimens, as well as amorphization, which occurs when heated specimens are cooled rapidly, results in a marked change in the dependence of dynamic characteristics in the glassy and the viscoelastic state on temperature and frequency. Annealing and amorphization of specimens alter the temperature interval in which deformation is dependent on frequency affect the magnitude of the dynamic modulus at constant frequency over a wide temperature range, and also result in a non‐uniform variation of the modulus difference at the maximum and minimum external frequencies. The shape of the maxima of mechanical losses in the low‐temperature principal and auxiliary relaxation regions observed in the case of annealed and amorphized specimens is different from that of the initial rubber. Since variations in the thermal prehistory cause no alteration in the molecular structure of rubbers, the phenomena observed can be attributed only to rearrangement of supramolecular structures. Variations in thermal prehistory exert no effect on the shape of the maxima of dipoleelastic dielectric losses because changes occur only in the mobility of segments with polar side groups, whereas the motion of supramolecular structures is absent. Density of the space network and the type of vulcanization (heat vulcanization at elevated temperature or radiation vulcanization at 20°C.) likewise influence the molecular order in rubberlike polymers and the dependence of the mechanical loss factor on temperature.
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Bartenew et al. (1967) studied this question.