Revival of the Induction Time Concept in the Theory of Polymer Crystallization

To monitor early stages of spherulite growth, a microscopical method has been worked out based on the photometrical measurement of the intensity of depolarized light during isothermal crystallization. Application of the technique to polypropylene yields the evidence of existence of nucleation induction time which reflects the processes taking place prior to the onset of spherulite growth, viz. the formation of stable crystal nuclei. Using the method, it is possible to evaluate also systems with a dispersed phase, the interfacial relations being reflected in the induction time of the nucleation on the surface of the dispersed phase. Application to the model PP/carbon fibres system yields differing results for carbon fibres of various provenance and of various properties.