Effect of Molecular Weight and its Distribution on the Crystalline Morphology of Polypropylene Materials

Abstract

The influence of molecular weight (MW) and molecular weight distribution (MWD) on the variation of crystalline morphology of polypropylene have been investigated. It was observed that neither the number-average molecular weight M_n nor the weight-average molecular weight M_w governs the morphology of the semi-crystalline state of PP materials, but the molecular weight distribution MWD appeared to be the key linear parameter that correlates with the crystalline morphology of the solid state. The dispersion of molecular weight indicates that a synergic effect exists between the high and low molecular weights which will determine the final crystalline morphology of PP materials.