Determination of Nonionic and Partially Hydrolyzed Polyacrylamide Molecular Weight Distributions Using Hydrodynamic Chromatography

Polyacrylamide and its copolymers of acrylic acid have wide application as flocculants and mobility control fluids in enhanced oil recovery. Detailed knowledge of the molecular weight and molecular weight distribution has not been available for these polymers because their exceptionally high molecular weight exceeds the capabilities of traditional techniques, such as size exclusion chromatography (SEC). The combination of hydrodynamic chromatography (HDC) and low-angle laser light scattering (LALLS) detection can be used to measure the molecular weight distribution of this group of polymers. Chromatographic conditions can be chosen so that the elution of the polymer is primarily a function of molecular weight and independent of the composition of the polymer. Weight-average molecular weights determined by this technique agree well with those calculated from intrinsic viscosity measurements.