Effect of continuous oscillatory shear on isothermal crystallization of non-nucleated and nucleating-agent-treated isotactic polypropylene assessed by dynamic mechanical analysis.

ABSTRACT Using dynamic mechanical analysis (DMA), we investigated the in situ crystallization kinetics of non-nucleated and nucleating-agent-treated isotactic polypropylene ( iPP) under continuous oscillatory shear during the entire crystallization process, and then compared the DMA results with those measured using differential scanning calorimetry under conventional quiescent crystallization. Our analyses, based on the Avrami equation, show that continuous oscillatory shear accelerated crystallization of non-nucleated iPP, but interfered with crystallization for nucleating-agent-treated iPP. Our results indicate that, for the present nucleating agent, its accelerating effect on crystallization cannot coexist with the accelerating effect of shear on crystallization. We attributed this difference to the disruptive effect of shear on growth and the different nucleation models of non-nucleated and nucleating-agent-treated iPP. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41685. [ABSTRACT FROM AUTHOR]