POLYMER SOLIDIFICATION AS A DISSIPATIVE PROCESS

Theoretical considerations are presented which show that because their conformational entropy is a nonlinear function of size, polymer molecules can only solidify under conditions far from equilibrium with the formation of dissipative structures. A dissipative structure is nonhomogeneous, it evolves with time from an initially space-dependent fluctuation, and has a characteristic size that depends upon the initial perturbation and the conditions that apply during its entire history. The glass transition is envisioned as the formation of the ultimate dissipative structure where all of the latent heat of crystallization is dissipated within the structure. The mechanism of glass formation can be described as the spinodal decomposition of a homogeneous liquid into two interpenetrating networks of high- and low-energy solids with a characteristic distance and a gradient of density and/or composition extending through both high- and low-energy regions.