Ammonium polymethacry late (APMA) was used as a suspending agent for the suspension polymerisation of methyl methacrylate. Aqueous APMA solutions were found to exhibit non-Newtonian behaviour. Their high viscosity decreased with increasing pH. Experimental data for drop break up were in agreement with Taylor's theory of viscous shear break up. It was also found that APMA interferes with the polymerisation kinetics. (c) 2006 Elsevier Ltd. All rights reserved.