A GENERALIZED THEORY FOR THE GLASS-TRANSITION TEMPERATURE OF CROSS-LINKED AND UNCROSSLINKED POLYMERS

A generalized theory for the glass transition temperature of crosslinked and uncrosslinked polymers has been developed, which takes into account the influences of end groups, branching, and crosslinking, and their functionality distribution. DiBenedetto's theory was found to correctly characterize the influence of crosslinks on the glass temperature. Normalized to constant crosslink functionality, the crosslink constant is a universal parameter suggesting that the entropic theory of glasses is applicable to crosslinked systems. Data on linear polymers and networks from the crosslinking of polymer chains, vinyl/divinyl‐copolymers and step‐growth polymers, such as polyurethanes, amine‐cured epoxies, or inorganic glasses, are presented. Copyright © 1990 John Wiley & Sons, Inc.