Kinetics of Synthesis and Characterization of Polyacrylamide

Abstract

<p>In Part I of this dissertation an experimental investigation of the molecular weight characterization of dextrans and non-ionic polyacrylamides by aqueous SEC with a DRI/LALLSP detector system is reported. Methodology for the determination of the molecular weight calibration curve and peak broadening parameters σ² (variance of a Gaussian instrumental spreading function) across the chromatogram have been developed. A blend of dextran standards and a blend of non-ionic polyacrylamide standards permit, with one injection, measurement of the molecular weight calibration curve over a wide range of retention volumes, respectively. Measurements with salt-free water as mobile phase have confirmed that some dextran chains may have a negative charge.</p> <p>In Part II of this dissertation aqueous solution polymerization of acrylamide at high monomer concentrations were done using potassium persulphate as initiator in the temperature range 20-70°C, to provide rate and molecular weight data under diffusion-controlled termination. Molecular weight development was followed by measurement of weight-average molecular weight with a low angle laser light scattering photometer (Chromatix KMX6). A kinetic model which accounts for diffusion-controlled termination was developed and used to identify strategies to maximize productivity and molecular weight.</p> <p>In Part III of this dissertation the solution copolymerization of acrylamide (AM) and acrylic acid (AA) was carried out with K₂S₂O₈ initiator at 40°C and 60°C. A new model for the rate of copolymerization of AM and AA in water as solvent was proposed. The differential rate equations for copolymerization derived from the model were transformed into differential equations for the homopolymerization. These differential equations have been solved on a digital computer to simulate or predict the conversions and molecular weight distribution as a function of time.</p>