Structural changes in polyacrylonitrile caused by a short intense energy pulse

The methods of IR spectroscopy, X-ray structural analysis and DTA were applied to study changes in the molecular and super-molecular structure of polyacrylonitrile subjected to a short intense energy pulse-laser irradiation or thermal impact. Both actions lead to the formation of conformers with absorption bands at 965 cm −1, and of a collection of polyconjugated structures. The chemical reactions proceeding during such action do not affect the ordered domains of the polymer. Three ranges were revealed in the temperature dependence of layer spacing. By a short energy impact, interchain interactions are enhanced due to improved packing of the structure, leading to a displacement of the high-temperature transition to higher temperatures. This results in improved thermostability of crystallites in the samples (this effect is the highest with laser irradiation). By DTA an additional maximum was detected, caused by the difference in the temperature range for cyclization processes in amorphous and crystalline polymer domains.