Crystallization and morphology of binary blends of linear and branched polyethylene

Abstract

The paper reviews crystallization kinetics and morphology studies of binary blends of a low molar mass linear polyethylene sharp fraction (M w=2500) and higher molar mass samples of various linear and branched polyethylenes. Cocrystallization and segregation phenomena occurring in these polymers are reported as a function of molar mass and degree of chain branching of the high molar mass component, blend composition, and crystallization temperature. Branched polyethylene with 1.5 mol% of ethyl groups cocrystallizes with the low molar mass linear PE fraction, whereas segregation of the low molar mass polymer is the dominant feature in the blends with polymers having a lower degree of chain branching (≤0.5 mol%). The applicability of differential scanning calorimetry, polarized light microscopy, and transmission electron microscopy to reveal cocrystallization and segregation phenomena in polyethylene is discussed.