The molecular weight distribution of polypropylene

Abstract

Abstract The Gel Permeation Chromatograph has been used for obtaining values of weight‐average and number‐average molecular sizes A w and A n and the heterogeneity indices A w /A n for a series of polypropylenes. Absolute values of M w and M n , the weight‐average and number‐average molecular weights, have also been obtained from the same samples with light‐scattering and osmotic pressure methods. Comparisons of the data from the gel permeation chromatograph with the data from the absolute measurements have been used for calculating Q , the constant used for converting A w and A n to the corresponding M w and M n values. Other correlations of interest, such as intrinsic viscosity versus weight‐average molecular weight and melt flow, and Newtonian viscosity versus weight‐average molecular weight, are also given.