Authors : O.D. Onukwli and P.K. Igbokwe
Abstract: The reaction of the polyesterification of glycerol, phtalic anhydride and dehydrated castor oil leading to the formation of alkyd resins was studied. Alkyd resins of 40% (I), 50% (II), 60% (III), 40% (IV), 50% (V), 60% (VI), 40% (VII), 50% (VIII) and 60% (IX) were prepared with three different catalysts-lead (II) oxide, lithium hydroxide and calcium carbonate. The extent of reaction (PA) and average degree of polymerization (DP) were determined from end-group analysis of aliquots of the reaction mixture at various time intervals. Results on the degree of polymerization indicated formation of appreciably high molecular weight resins, soluble in xylene (3:2 dilution), with qualities varying with oil length. The untreated and dehydrated castor oil had acid and saponification values of 2.89 and 182.0 and 5.9 and 189.40, respectively. The variation of drying time with the catalyst used showed that the shorter alkyd resins (40%) dried faster than the medium (50%) and long alkyds (60%). In addition, the reaction completion time for the 40% oil alkyds was shorter than for medium and long alkyds.
O.D. Onukwli and P.K. Igbokwe , 2008. Production and Characterization of Castor Oil-Modified Alkyd Resins. Journal of Engineering and Applied Sciences, 3: 161-165.