A systematic polymerization kinetic study of methyl acrylate with an added initiator, peroxodisulfate, in the presence of low-power ultrasound was done. The polymerization experiments were conducted at various concentrations of monomer and initiator at different temperatures (303-323 K). The polymerization was found to proceed without an induction period, and the steady state was attained in a fairly short time. The rate of monomer disappearance showed a second-order dependence on monomer concentration. The chain lengths of the polymer were calculated, and we found that the chain length increased with increasing monomer concentration and decreased with increasing initiator concentration. The reaction scheme proposed is based on the kinetic studies that indicated linear termination by sulfate-ion-radical-incorporating direct reaction between the monomer and the initiator. (c) 2008 Wiley Periodicals, Inc.