Nonisothermal crystallization, melting behavior, and morphology of polypropylene/linear bimodal polyethylene blends

Abstract

AbstractThe nonisothermal crystallization, melting behavior, and morphology of isotactic polypropylene (PP)/linear bimodal polyethylene (LBPE) blends were studied with differential scanning calorimetry, scanning electron microscopy, and polarized optical microscopy. The results showed that PP and LBPE were miscible to a certain extent, and there was no obvious phase separation in the blends. The modified Avrami analysis, Ozawa equation, and Mo method were used to analyze the nonisothermal crystallization kinetics of the blends. The values of the Avrami exponent indicated that the crystallization nucleation of the blends was homogeneous, the growth of spherulites was three‐dimensional, and the crystallization mechanism of PP was not affected much by LBPE. The crystallization activation energy was estimated by the Kissinger method. The results obtained with the modified Avrami analysis, Mo method, and Kissinger method agreed well. The addition of a minor LBPE phase favored an increase in the overall crystallization rate of PP, showing some dilution effect of LBPE on PP. The PP spherulites decreased obviously with increasing content of LBPE. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008