Viscoelastic behaviour and structure of polymers

Abstract

This review article reflects the present position as regards investigation of the relationship between structure and various physical relaxation properties of polymers (on molecular and supramolecular levels). Both the various mechanisms of relaxation processes and the methods for their mathematical representation are considered in the Introduction. The experimental data from investigations of relaxation phenomena in amorphous polymers are discussed and a wide classification of the observed ranges of relaxation given/ Much attention is given to the characteristics features of the relaxation processes in crystalline polymers; further, the authors underline the variety of the characteristic features as compared with those of the amorphous solid and rubber-like polymers. The processes of mechanical, dielectrical and magnetic relaxation in polymers of different types are compared. The authors describe the characteristics features of relaxation phenomena in copolymers and mechanical polymer mixtures, compatible (homogeneous) and incompatible (micro and macroheterogeneous). The influence of the type and size of the supramolecular structures on the character of processes of mechanical relaxation in rubber-like and solid amorphous and crystalline polymers is considered. The authors discuss the relationship between relaxation phenomena and the processes of external friction of polymers as well as their rheological properties.