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Gamage, Padmasiri Kankanam (2009) Use of selected vegetable oils as plasticiser/stabiliser for PVC. Doctoral thesis, London Metropolitan University.
Three different vegetable oils: Rubber seed oil, Neem oil and Mee oil were used in specific PVC formulations in order to investigate the affect of these oils in the PVC phase. The oils were characterised for fatty acids profile and other properties. Oils and their hydrolysed products were epoxidised by peroxyformic acid generated 'insitu' by reacting methanoic acid with hydrogen peroxide. Reaction conditions were optimised and the process modified to allow for large-scale laboratory production of the epoxidised oils. The extent of epoxidation was quantified by the Iodine value, FTIR NMR and TLC analysis. In addition, epoxidised products of oil derivatives were characterised in terms of Iodine value, oxirane content, density, molar masses and solubility parameters. Concentrations of oil derivatives in PVC were optimised for adequate processing and mechanical behaviour. Effectiveness of epoxidised oils in PVC to enhance heat stability was studied. The stabilising effects of epoxidised Neem oil and epoxidised Mee oil were kinetically modelled showing that ENO was effective in retarding degradation in PVC; moreover 10 phr level of ENO showed the least degradation with the highest activation energy. Migration of epoxidised Neem oil in a PVC/NBR system was studied using a statistical experimental design with three variables or factors. Response equations were generated from the design relating migration and diffusion of oil derivatives in terms of plasticiser concentration, nitrile content and crosslink density. Also, the statistically designed experiments indicated that ENO concentration in PVC and the polarity of the receiving polymer (NBR) were the main factors influencing migration.
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