Characteristic Features of Relaxation Processes in Thermoplastic Heat-Resistant Polymers Related to their Structure

The article presents an analysis of structure-property relations of thermoplastic heat-resistant polymers (HRP) polyimides and polybenzoxazole evaluating stress relaxation conditions. The main characteristic features of mechanical behavior of HRP, such as very high glass transition temperatures (250 - 500 C) and existence of relaxation sstransitions (solid-solid transitions) were considered in comparison to peculiarities of their chemical structure and morphology. The influence of of hinge-type groups in polymer macromolecules on glass transition and relaxation transition temperatures was assessed.