A phenomenological model for flow-induced crystallization

The Hamiltonian Bracket Formulation combined with the Avrami equation was u sed to develop a model for the flow-induced crystallization of polymers. Th e amorphous part of the chain was modeled as a non-linear Hookean dumbbell and the crystalline part as a rigid rod. Evolution equations for the config uration tensors of the two phases and for the degree of crystallinity were obtained and were subsequently solved for the transient and cessation case under different flow conditions. The model has a number of parameters that can be obtained (with the exception of one) from rheological measurements a nd quiescent crystallization experiments. The model predicts the variation in the degree of crystallinity and the induction time as a function of the polymer properties and the processing conditions. The model can also be use d to predict the development of birefringence. The predictions of the model are in general agreement with the experimental observations.