The free-radical terpolymerization of a monocyclic terpene, namely, limonene (Lim), with styrene (Sty) and methyl methacrylate (MMA) in xylene at 80 +/- 0.1degreesC for 2 h, with benzoyl peroxide (BPO) as an initiator under an inert atmosphere of nitrogen was extensively studied. The kinetic expression was R(p)alpha[BPO](0.5)[Styl](1.0)[MMA](1.0)[Lim](-1.0), where R-p is the rate of polymerization. The overall energy of activation was calculated as 26 kJ/mol. RP decreased as [Lim] increased. This was due to a penultimate unit effect. The Fourier transform infrared spectra of the terpolymer showed bands at 3025-3082, 1728, and 2851-2984 cm(-1) due to C-H stretching of phenyl (-C6H5) protons of Sty, -OCH3 of MMA, and trisubstituted olefinic protons of Lim, respectively. The H-1-NMR spectra showed peaks at 7.3-8.1, 3.9-4.4, and 5.0-5.5 delta due to the phenyl, methoxy, and trisubstituted olefinic protons of Sty, MMA and Lim, respectively. The values of the reactivity ratios r(1) (MMA; 0.33) and r(2) (Sty + Lim; 0.06) were calculated with the Kelen-Tudos method. (C) 2003 Wiley Periodicals, Inc.