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Abstract
The radical co-polymerization of limonene (Lim) with N-vinyl pyrrolidone (N-VP) initiated by azobisisobutyronitrile (AIBN) in dioxane was carried out at 80 ± 0.1°C for 1 h under the inert atmosphere of nitrogen. The kinetics expression is, R p ∝ [AIBN]0.5 [N-VP]1.0 [Lim]−1.0. The overall activation energy has been calculated as 30 kJ/mol. The FT-IR spectrum of the co-polymer shows the bands at 1667 cm−1 due to =C=O group of N-vinyl pyrrolidone and at 1705 cm−1 due to C=C stretching of trisubsitituted olefinic protons (=C=CH–CH2–) of limonene, respectively. The 1H-NMR spectra show peaks at 5.5 δ due to trisubstituted olefinic protons of limonene. The value of reactivity ratios r 1 (N-VP) = 0.075 and r 2 (Lim) = 0.02 using the Kelen–Tüdos method has been evaluated. The Alfrey–Price Q–e parameter for limonene has been calculated as 0.047 and 0.21 respectively. The values of r 1 r 2 (0.0015) and widely differing e values of N-VP and limonene (e N-VP = −1.62, e Lim = 2.1) suggested that co-polymerization has tendency towards the alternating co-polymer. DSC shows the T g value of the co-polymer at 67°C. The TGA curve shows that the co-polymer is stable up to 363°C. The molecular weights of the co-polymers have been evaluated by gel-permeation chromatography.
