Charles P. Lusignan

Size Exclusion Chromatography of Branched Polyethylenes to Predict Rheological Properties

ABSTRACT Three methods of predicting dynamic viscosity of branched polyethylenes from size exclusion chromatography (SEC), refractive index/light-scattering detection data were examined: relating parameters in the Cross viscosity equation to molecular weight averages, use of a mixing rule, and a method based on the similarity of the cumulative molecular property distributions to a dimensionless viscosity versus frequency plot. The use of accurate SEC data was emphasized. The third “curve similarity” method provided the most promising results. The use of cumulative g′ (the molecular contraction factor based on intrinsic viscosity) distributions, in addition to cumulative molecular weight distributions, enable very useful sample comparisons.