The Influence of Structure on the Molecular Mobility and Rheology of Amorphous Macromolecular Systems

A brief review with emphasis on the important open questions is presented of our knowledge of the factors influencing the chain mobility and mechanical pro properties of amorphous polymeric systems. It is necessary to give more precise meaning to the concepts of "chain entanglements" and "free volume" and to relate these to the structure of the repeating unit and to the gross chain structure of the macromolecules. From studies of the viscosity in bulk or in concentrated solution of model polymers and novel polymers we propose to determine the influence on the mobility of heterogeneity in chain length distribution of added diluent, and of the stereochemical chain structure. The initial data on polystyrenes of narrow distribution prepared in anionic synthesis and of mixtures of these are presented here.