RHEOLOGICAL MECHANISM AND OVERVIEW OF NUCLEATED CRYSTALLIZATION KINETICS

Although the function of a nucleating agent in shortening the initiati on time and thus enhancing the crystallization rate is well understood , an increased rate at higher melt --> crystalline conversions (e.g., greater-than-or-equal-to 10%), where the active nuclei are in abundanc e, is less straightforward to explain. Such a behavior is typical of n ucleated crystallization of polymer melts. However, its existence and, especially, the underlying mechanism have not been discussed in the l iterature. In this paper, we have presented (1) a rheological techniqu e for studying the crystallization kinetics and shown it to be more se nsitive than conventional techniques like differential scanning calori metry (DSC) and (2) two possible mechanisms to account for enhanced ra te at higher conversions for nucleated crystallization of polymer melt s.