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Azobisisobutyronitrile-initiated free-radical copolymerization of limonene with vinyl acetate: Synthesis and characterization



The solution copolymerization of limonene (Lim) and vinyl acetate (VA) with azobisisobutyronitrile (AIBN) as an initiator in dioxane at 65 ± 0.1°C for 2 h under a nitrogen blanket has been carried out. The kinetic expression is [AIBN]0.5[VA]1.0[Lim]−1.0. The overall energy of activation has been computed to be 30 kJ/mol. Fourier transform infrared spectroscopy has shown bands at 1731 cm−1 due to acetoxy protons of VA and at 1689 cm−1 due to trisubstituted olefinic protons ([BOND]CH[DOUBLE BOND] CH[BOND]CH2) of Lim. 1H-NMR spectroscopy of the copolymer has shown peaks at δ = 1.2–1.5 and δ = 5.3–5.6 due to acetoxy and trisubstituted olefinic protons of VA and Lim, respectively. The reactivity ratios have been calculated to be 0.05 for VA and 0.011 for Lim with the Kelen–Tüdos method. The glass-transition temperature of the copolymer, determined by differential scanning calorimetry, is 32.4°C. The copolymer is likely biodegradative in nature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007