Synthesis and Characterization of Oil-Modified Alkyd Resin from Epoxidized Neem Oil

Abstract

The aim and objective of this work is to synthesize a greener alkyd resin by substituting petroleum based epoxides in alkyd resin modification. Chemical transformation of the existing functional group present in neem oil via epoxidation, epoxy functionality was inserted and used as substitute to petroleum based epoxide. Epoxidization of neem oil was carried out with per-acetic generated in-situ at 50°C. Alkyd resin with oil-length of 64.5% was synthesized from the epoxidized neem oil ENO. Polyesterification reaction of the oil was carried out using glycerol and phthalic anhydride at 250°C to synthesize epoxidized neem oil alkyd resin ENOMAR. The resin where cured using methyl ethyl ketone peroxide MEKP and 12% cobalt naphthalate in toluene; this was applied uniformly on a different glass plate substrate and heated in an oven at 80°C and 120°C respectively at different time intervals. Films properties such as drying time, set to touch time and chemical resistance of the resins were determined. Minimum drying and set to touch time was recorded at 15 and 9 hrs at 120°C for 120 mins, while minimum value of 17 and 11 hrs was also recorded at 80°C for 120 min. Chemical resistance of the resin show good resistance in 10% HCl and distilled water. The resin also shows relatively good resistance in 1% NaCl and a poor result in 1% NaOH. Infrared analysis result of the resin shows broad and sharp peaks at 1732 cm-1, 2928 cm-1 and 3465 cm-1. Assessments of the properties show that epoxidized neem oil modified alkyd resin ENOMAR has film properties that are characteristic of good alkyd resins.