Microrheological modeling of flow-induced crystallization

The problem of flow-induced crystallization (FIC) of polymer melts is addre ssed via a microrheological approach. In particular, the Doi-Edwards model with the so-called independent alignment approximation (DE-IAA) is used to calculate the now-induced change of free energy. Subsequently, the crystall ization induction time, i.e., the nucleation characteristic time, is calcul ated in isothermal steady sheer and uniaxial elongational flows. Asymptotic , analytical expressions for the induction time are also derived in the lim it of low and high Deborah number (the product of the deformation rate and the polymer relaxation time). The DE-IAA model is found to give more realis tic predictions than those of simpler, dumbbell-like models already propose d in the literature. When compared to existing FIC experimental data in she ar flow, good quantitative agreement is found with the polymer relaxation t ime as the only adjustable parameter of the model.