STRUCTURAL RELAXATION OF HETEROCYCLIC POLYMER NETWORKS IN THE GLASS-TRANSITION REGION

Heterocyclic polymer networks prepared by a catalytic copolymerization of the epoxy oligomer with hexamethylene diisocyanate at different ra tios of the comonomers were characterized by in their glass transition regions. The glass transition temperatures, apparent activation entha lpies, and the specific heat capacity increments in the glass transiti on region correlated with the sample composition, whereas the index of the relaxation time distribution was nearly composition-invariant. Th e structural relaxation process was described by an equation for the c onfiguration entropy. The parameters of the studied materials were det ermined by a fit to a wide range of thermal histories.