Crosslinked poly(butyl acrylate-co-2-ethylhexyl acrylate) [P(BA-EHA)] latex was synthesized by seeded emulsion polymerization. P(BA-EHA)/poly(vinyl chloride) (PVC) composite latex was prepared using P(BA-EHA) latex as the seed. The effects of the amount of P(BA-EHA) on the latex particle diameters and mechanical properties of the materials are discussed. The grafting efficiency (GE) of P(BA-EHA)-grafted vinyl chloride (VC) in the synthesized resin was investigated, and the GE increased with an increasing P(BA-EHA)/VC ratio. The morphology of P(BA-EHA)/PVC was characterized using TEM, SEM, and DMA. TEM indicated that the particles of the P(BA-EHA)/PVC composite latex have a clear core-shell structure. DMA illustrated that the compatibility between P(BA-EHA) and PVC was well improved. With an increasing P(BA-EHA) content, the loss peak in the low-temperature range became stronger than that of pure PVC, and the maximum values of the loss peaks gradually shifted to higher temperature. SEM showed that the fractured surface of the composite sample exhibited better toughness of the material. The notched impact strength of the material with 4.2 wt % P(BA-EHA) was 11 times that of PVC. TEM showed that P(BA-EHA) was uniformly dispersed in the PVC matrix and that the interface between the two phases was indistinct. (C) 2003 Wiley Periodicals, Inc.