Extensional rheology and stability behavior of alumina suspensions in the presence of AMPS-modified poly(carboxylate ether)-based copolymers

A series of polycarboxylate ether-based copolymers that include acrylic acid, 2acrylamido-2-methylpropane sulfonic acid, and polyethylene glycol-1000 was synthesized and the performance of these copolymers as rheology modifiers in aqueous alumina suspensions was characterized. We discussed the effect of monomer feed ratio and molecular weight on dispersing ability of these copolymers and on extensional behavior of alumina suspensions. Results of zeta potential analysis determined that using the copolymers even at 0.5 wt% results in all-negative zeta potentials for the entire pH range (2–12). These copolymers immensely affect the extensional rheological behavior of alumina suspensions— while 20 vol% pure alumina suspension showed severe strain hardening behavior, suspensions with 1 wt% copolymers and 35 vol% alumina particles displayed no strain hardening. In this series, the copolymer with lowest molecular weight decreased the extensional viscosity of suspensions at the rupture of thread with 3 orders of magnitude as well.