QUANTITATIVE-EVALUATION OF EARLY-STAGE GROWTH-KINETICS OF HETEROGENEOUSLY NUCLEATED SPHERULITES - HAS THE NUCLEATION INDUCTION TIME A NONZERO VALUE

Early stages of polymer crystallization are pronouncedly influenced by the presence of a foreign phase, the surface of which may increase th e formation of crystal nuclei. However, measurement of the initial sta ges of the crystallization with the aid of conventional methods is ext remely difficult. The possibility of using the Avrami equation in its classic form for that purpose is discussed and found inappropriate. Ch aracterization of the initial crystallization stages is corroborated u sing the crystallization induction time, which represents the most pro bable value of the nucleation times of individual spherulites. The ind uction time of polypropylene without a nucleation agent was found to b e positive.