Synthesis and Characterization of Water Soluble Polymers

Abstract

<p>This thesis has been written in three parts. Part I deals with the rheological response of dilute solutions of high molecular weight polyacrylamides at low shear rates. The non-Newtonian effects were found to be significant for polyacrylamides with number average molecular weights exceeding 10⁶. The molecular weight average-intrinsic viscosity relationship most widely used in literature was found to be valid when the intrinsic viscosity was measured at high shear rates where the polymer solutions approached Newtonian behaviour. A new relationship was developed relating the number average molecular weight to the intrinsic viscosity extrapolated to zero shear rate.</p> <p>Part II is an experimental investigation of the free-radical chain polymerization of acrylamide in water with potassium persulfate initiator. Conditions were such that the polymers produced had a number average molecular weight in excess of one million. Molecular weight averages were measured by viscometry, accounting for the non-Newtonian effects by the methods developed in Part I. Values for the transfer constants to the monomer and to the initiator were estimated at 25°C and 40°C and compared to the literature values.</p> <p>In Part III, a new method was developed to estimate the reactivity ratios from composition-conversion data, based on non-linear regression. Previously published experimental data for the copolymerization of acrylic acid and acrylamide were analysed by the new method, and the results compared to those reported by the original investigators. Composition-conversion data were collected for this copolymerization system at intermediate conversion levels and over a limited range of compositions. Values for the reactivity ratios at 40°C were obtained from these data by the new algorithm, and compared to the literature values.</p>