GLASSY STATE RELAXATION AND DEFORMATION IN POLYMERS

An overview of a nonequilibrium glass theory is presented to describe the structural relaxation and deformation kinetics of polymeric glasses, compatible blends, and particulate composites. The glassy state relaxation is a result of the local configurational rearrangements of molecular segments, and the dynamics of holes (free volumes) provide a quantitative description of the segmental mobility. On the basis of the dynamics of hole motion, a unified physical picture has emerged which enables us to discuss the structure relaxation, physical aging, and glassy state deformation. The links between the bulk and shear relaxations, the change in deformation from linear to nonlinear viscoelastic responses, and the nonlinear viscoelastic nature of plastic deformation are discussed. Theoretical expressions are presented for the determination of the PVT (pressure-volume-temperature) behavior, for the elucidation of the equilibrium and nonequilibrium nature of the glass transition, for the calculation of viscoelastic response, and for the prediction of yield behavior and stress-strain relationships of these polymeric systems.