Influence of thermal history on crystalline morphologies of isotactic polypropylene in its miscible blends with polybutene‐1

Abstract

The miscibility behaviors in blends of isotactic polypropylene (iPP) and polybutene-1 (PB) have been studied using in-situ FTIR imaging. The heterogeneous melt of 3/7 iPP/PB blends were formed at 250, 220, and 1808C and then quenched to the same crystallization temperature of iPP at 1258C, respectively. Evolution processes of composition distribution during crystallization were monitored according to their characteristic peaks, and the results suggest a trend from local concentration to uniform dispersion of PB fraction. Further studies of the PB fraction as the distance from the growth front of iPP spherulite indicate an irreversible phase behavior with the progress of thermal history. The cyclic melting and crystallization favor the mixing of iPP/PB blend. Meanwhile, the nonlinear growth rate of iPP spherulite is mainly responsible for compatible promotion of iPP/PB blend, which hinders the transportation of iPP chains to its growth front.