REGIME TRANSITIONS IN A NONREPTATING POLYMER - CROSS-LINKED LINEAR POLYETHYLENE

The bulk crystallization kinetics of linear polyethylene, cross-linked to various levels using Vul-Cup R peroxide, have been determined. The kinetics of the sol fractions of the cross-linked polyethylene conform to regime I growth, while the gel fractions show primarily regime III growth. The regime II-regime III transition can be observed in the gel fractions of high cross-link density over the temperature range 109-113 °C. The behavior is interpreted in terms of the effect of cross-links on the competing rates of surface nucleation and substrate completion. Literal interpretations of Avrami coefficients suggest a disklike morphology that becomes increasingly fibrillar at high levels of cross-link density. © 1990, American Chemical Society. All rights reserved.