Calculation of Stresses in Crosslinking Polymers

Abstract

A general constitutive model is presented for calculating the evolution of stresses in crosslinking polymers. The analysis is valid for thermo- and chemorheologically simple polymers and for time-dependent strain histories where the total strain at any time is not large, such that linear viscoelasticity applies. We identify the material parameters required and outline experimental and theoretical methods for their determination. This formalism is then used to calculate the development of cure stresses for an epoxy wherein the glass transition temperature exceeds the cure temperature during the reaction. Finally, we discuss practical methods of stress minimization through control of the cure cycle.