Investigation of Reactivity Ratios for the AMPS/AAm/AAc Terpolymer and Associated Copolymers

Abstract

Water-soluble polymers of acrylamide (AAm) and acrylic acid (AAc) have significant potential in enhanced oil recovery, as well as in other specialty applications. However, to improve the shear strength of the polymer, it may be beneficial to add a third comonomer to the pre-polymerization mixture. Homopolymerization kinetics of acrylamide and acrylic acid have been studied previously, as have the copolymerization kinetics of these two comonomers. Therefore, in the current study, the kinetics of three additional systems are investigated: copolymerization of AMPS/AAm and AMPS/AAc and terpolymerization of AMPS/AAm/AAc.

Copolymerization experiments for both AMPS/AAm and AMPS/AAc were designed using two optimal techniques (Tidwell-Mortimer and the error-in-variables-model (EVM)) and terpolymerization experiments for AMPS/AAm/AAc were optimally designed using EVM. From these optimally designed experiments, accurate reactivity ratio estimates were determined for AMPS/AAm, AMPS/AAc and AMPS/AAm/AAc.

To better understand the error associated with each system, reactivity ratio point estimates for both the binary and ternary systems were presented using joint confidence regions (JCRs). The estimates were evaluated by comparing model predictions to experimental data, and the effect of experimental error was studied using sensitivity analyses. Finally, a direct comparison of binary and ternary reactivity ratios (for similar systems under the same experimental conditions) was possible for the first time.