Synthesis and characterization of copolymers of limonene with styrene initiated by azobisisobutyronitrile

The radical copolymerization of limonene with styrene by azobisisobutyronitrile in xylene at 80 +/- 0.1 degreesC for 2 h, under inert atmosphere of N-2, yields alternating copolymers. The kinetic expression is R-P proportional to [I](0.5)[Sty](1.0)[Lim](-1.0). The overall activation energy is calculated as 41 kJ/mol. The FTIR and H-1-NMR spectra of copolymers show bands at 3000 and 1715 cm(-1) and peaks at 6.8 delta and 5.3 delta due to phenyl protons of styrene and trisubstituted olefinic protons of limonene, respectively. The values of reactivity ratios r(1) (Sty) = 0.0625 and r(2)(Lim) = 0.014, calculated by Kelen-Tudos method. The Alfrey-Price Q-e parameters for limonene are 0.438 and -0.748, respectively. The penultimate unit effect is favoured in the present system and the value of phi is 38.49. (C) 2004 Elsevier Ltd. All rights reserved.