Measurement of Molecular Weight Distribution of Polyacrylamide By Turbidimetric Titration

Abstract

<p>This thesis reports on a method for measuring the molecular weight distributions of polyacrylamide - a water-soluble polymer. The method which is turbidimetric titration involves the incremental addition of non-solvent or precipitant to a solution of polymer and encourages aggregation. At each point of the titration, optimum condition was obtained. The optimum condition was defined by proper application of Mie theory of light scattering functions. These scattering coefficients and scattering functions were further investigated over a broad range of particle size. Broad polymers were investigated, as this polymer-polyacrylamide can only be made via free-radical polymerization. The conditions necessary to satisfy the inherent assumptions were specified and justified by the experimental technique. A very high molecular weight polymer was polymerized by free radical polymerization in the presence of an electrolyte. The influence of electrolyte, and the method of mixing were studied.</p> <p>The quality of the distributions and averages obtained by the method was assessed by GPC measurements and viscosity measurements. The method is capable of giving accurately the molecular weight distributions of any polymer in principle, especially when the weight average molecular weight is greater than five million.</p>