Authors: Olujinmi Moses Folarin, Ighodalo Clement Eromosele and Catherine Oluyemisi Eromosele
African Journal of Pure and Applied Chemistry Vol. 5(7), pp. xxx-xxx, July 2011
Abstract
Ximenia americana seed oil (XSO) and Balanites aegyptlaca seed oil (BSO) were soxhlet extracted and characterized. The iodine values were 158.3 and 102.6 gl2 100g-1 for XSO and 850, respectively. The oxirane content for the epoxidized oil derivatives, EXSO and EBSO, were 4.9 and 4.1%, respectively. Kinetic studies of thermal degradation of poly (Vinyl chloride), (PVC) in the temperature range, 170 to 1900C under nitrogen atmosphere were conducted in the presence of the oils and epoxidized derivatives. The effect of the oils was evaluated from the rate of dehydrochlorination at 1%degradation, RDH and the time required for degradation to attain 1% conversion tDH. The additives retarded dehydrochlorination rate of PVC. The mechanism of thermal stabilization of PVC by the oils was attributed to trapping of HCI through addition reactions of the latter with unsaturated fatty acids. The resultant order of stabilization was, EXSO > EBSO > XSO > BSO. The latter was consistent with the results of viscosity measurements on degraded polymer and from thermogravimetric studies. The order of stabilization was corroborated by the activation energies, (Ea) calculated from the rate constants of dehydrochlorination process. The highest value of 111.84 kJmol-1 was obtained for PVC with 3 wt-% EXSO additive. In air, PVC was unstabilized by XSO and BSO and was adduced to dominant oxidative reactions of unsaturated fatty acids and consequent prevention of HCI-trapping addition reactions.