Hydrogenated cardanyl acrylate (HCA) and cardanyl acetate (CAGE) were synthesized from cardanol. The copolymerizations of HCA, CACE, and styrene (S) with methyl ethyl ketone peroxide (MEKP) and cobalt salt as the initiator were studied by FTIR. Based on FTIR results the reactivity ratios of the three copolymerization systems S-HCA, S-CACE, and HCA-CACE were determined by three different methods (Mayo-Lewis, Fineman-Ross, and Kelen-Tudos). Results obtained from the three methods are in good agreement. Instantaneous compositions and composition shift as a function of conversion is calculated for the S-HCA-CACE system with different feed compositions. (C) 2003 Wiley Periodicals, Inc.