CONSTITUTIVE EQUATION FOR CURE-INDUCED STRESSES IN A VISCOELASTIC MATERIAL

Branched polymer systems such as epoxies, polyurethanes, etc., can develop significant stresses during cure. These stresses principally arise from the shrinkage caused by chemical reactions in the postgel regime and can result in cracking of the material. In this paper we drive a constitutive equation that describes the development of elastic and viscoelastic stresses during cure. An interesting coupling is found between the equilibrium and relaxing components of the stress, due to the memory effects present in a viscoelastic fluid. These memory effects increase the residual elastic stresses at infinite time. © 1990, American Chemical Society. All rights reserved.