In this paper, the chain transfer method was adopted to study the graft copolymerization of butyl acrylate onto poly(vinyl chloride) (PVC) in emulsion. This approach to the synthesis of graft copolymers was first suggested by Flory, and was experimentally demonstrated by Hayes, Blumczynski and Mayo. The work reported here shows that for the chain transfer method, the grafting efficiency does not increase, as Flory’s chain transfer theory predicted, but decreases with increasing copolymerization temperature. An explanation of these observations is proposed. In addition, FTi.r. was used to study the resultant graft copolymer and the parent homopolymers in order to investigate the structural changes in PVC consequent on grafting. Thermogravimetry results showed that the thermal stability of the graft copolymer is better than those of PVC and PVC/poly(butyl acrylate) blend.