Modeling the interactions between light and crystallizing polymer during fast cooling

In this work, an experimental set-up able to quench thin polymer films whilst recording the sample thermal history as well as the overall and depolarized light intensities of a laser beam emerging from the sample is described. The interactions between the light beam and the crystallizing material have been modeled accounting for absorption and scattering phenomena. The proposed model was found to be able to reproduce the experimentally observed behavior of light intensities and it was validated by comparison with conventional DSC analysis. On the basis of this model, a method to obtain crystallinity evolution is proposed and applied to some fast cooling runs. The method was applied to quenching runs of an iPP carried out under cooling conditions more than one order of magnitude faster than those allowed for the DSC technique. The crystallization temperature dependence upon cooling rate was obtained from these runs in a cooling rate range never before explored.