Correlation Between Local and Bulk Relaxation Phenomena in Glassy Polystyrene

Abstract The intermolecular forces are of great importance to scientists in a wide field of disciplines as the progress of interactions between molecules determines the bulk properties of substances. It is a matter of fact that the approximation of thermodynamic and transport properties of polymers requires a realistic intermolecular potential associated with the topological constraints of the matter, namely the specific one‐to‐one secondary interactions between molecular groups. The out‐of‐equilibrium volume relaxation in glassy polymers remains confined to the phenomenological observation of bulk properties. The Lennard‐Jones (LJ)‐type potentials and the Tait equation are compared in this communication. It is shown that the subtle relaxation responses observed in glassy polymers can be suitably described using both the local (LJ) interactions and the phenomenological Tait equation for bulk behavior. The approach is based on the oversimplified assumption that the volume relaxation phenomena are the isotropic manifestation of random relaxations of local directional interactions of secondary bonds. The results appear surprisingly appealing, given the straightforward approach.