Epoxidised resins from natural renewable resources

Abstract

This research was based on the premise that vegetable oils may present a viable alternative to petrochemical feedstocks for the creation of epoxy resins. Vegetable oils are a natural and renewable product in an age of dwindling fossil oil reserves and growing demand from the energy and materials sectors. Vegetable oils present as likely candidates for conversion into polymeric materials because of their molecular structure. They already contain the long carbon chains that define polymeric materials, as well as carbon to carbon double bonds which can be converted to functional groups through chemical synthesis. For this research locally sourced vegetable oils high in unsaturated fatty acids such as oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3) were epoxidised with peroxyacetic acid formed in situ by the reaction of aqueous hydrogen peroxide and acetic acid in the presence of an acidic ion exchange resin as catalyst. The reaction was carried out in a constantly stirred batch reactor, stirred with a low profile ship’s anchor stirrer. A number of parameters were examined including: (1) the molar ratios of ethylenic unsaturation to acetic acid to hydrogen peroxide, (2) the amount of catalyst loading, (3) the steady state operating temperature of the reactor, (4) the time required to achieve maximum carbon to carbon double bond consumption, (5) the time required to achieve maximum oxirane group formation. Results of epoxidation where examined using Fourier Transform Infrared Spectroscopy and the titration methods for determining iodine value and oxirane-group oxygen content.Initial testing was conducted on linseed oil, sunflower oil and mutton tallow, but it was decided that locally sourced hemp oil would become the primary focus of this research. This was because hemp oil is high in saturated fatty acids, and there appeared to be little in the existing literature regarding the epoxidation of hemp oil. It was found that optimum processing conditions for hemp oil existed at Molar ratio: Hemp oil (1.0 mole of double bonds) : Acetic acid (0.67 moles) : H2O2 (1.0 moles) Catalyst loading: 15 wt% of hemp oil Reaction time: 7 hours Reaction temperature: 75°C At these conditions an 88% conversion of double bonds to epoxy groups was found to occur. This result was comparable to the results of other authors conducting similar research