In this work, the compatibilization of blends of plasticized polyvinyl chloride (PVC) and polystyrene (PS) with poly(styrene-co-n-methylolacrylamide) (PSnMA) was investigated. The PSnMA was synthesized by emulsion polymerization with different amounts Of n-methylolacrylamide (nMA). Particle size and phase behavior was determined by scanning electron microscopy, and mechanical properties were determined in an Universal Testing Machine. Micrographs revealed that in appreciable size reduction of the dispersed phase was achieved when small amounts of PSnMA were added to the blend, and as the amount of nMA was increased, particle size decreased, When the (PVC/PS/PSnMA) blend was subjected to solvent extraction to remove PS and unreacted PVC, the residue showed a single T-g. Tensile modulus and the ultimate strength of the blends increased with PSnMA content. (C) 2008 Wiley Periodicals, Inc.