Small angle light scattering by ordered polymer solutions

Abstract

The method of small angle scattering of polarized light permits one to investigate fast processes of ordering of polymer solutions in the course of crystallization, and in particular, to study the kinetics of spherulite growth. The registration velocity of the scattering patterns was not lower than 2 photos s^–1, the exposure did not exceed ½ s, and the range of the size registered was from a fraction of a micron to several microns. This method was used for studying the temperature dependence of the spherulite growth rate during isothermal crystallization of polypropylene solutions in decalin in the absence of the “kinetic memory” effect. The growth rate followed fairly closely the general thermodynamic relationships. Crystallization of the polypropylene solution in decalin carried out with stretching of the jet leads to the growth of spherulites flattened with respect to the stretching direction. When the take-up velocity grows, the flattening of the spherulites increases and their radius decreases. A general formal explanation is given of the phenomenon of the flattening of the spherulites in the course of their growth in a mechanical field and of the peculiarities of the supermolecular order formation during molecular orientation.