Synthesis and Characterization of Alkyd Resin from Albizia lebbeck (frywood) seeds

Abstract

Alkyd resin was synthesized from the Albizia lebbeck (frywood) seed oil (FWO) and the physico-chemical properties of both the oil and the consequent alkyd resin were studied. Fourier Transform Infra-red (FTIR) spectroscopy was used to investigate the functional groups present in the alkyd resin. MATLAB was used to generate model equations for the extent of reaction for the synthesis of the alkyd resin. The oil extracted from the plant's seeds has a percentage yield of 17.32%w/w, exhibited yellow colour and was liquid at room temperature. Other physico-chemical properties of the oil such as density, specific gravity (30ºC), refractive index (30ºC), viscosity (30ºC), saponification value, iodine value, acid value, free fatty acids and peroxide value were determined to be 0.89g/cm 3 , 0.84, 1.48, 27.064m 2 /S, 207.22mgKOH/g, 122.18gI 2 /100g, 8.98 mgKOH/g, 4.52% and 10.00mEq/kg respectively. The synthesized alkyd resin from frywood seed oil (FWOAR) was dark-brown in colour while that of the commercially prepared alkyd resin (CPAR) was colourless. Physico-chemical properties of FWOAR such as specific gravity (30ºC), viscosity (30ºC), saponification value, iodine value and acid value were investigated to be 47.58, 36.50, 361.85mgKOH/g, 32.33gI 2 /100g and 7.01mgKOH/g respectively. These values, except that of saponification (361.85mgKOH/g vs 263.97mgKOH/g), were not significantly difference when compared to those of CPAR that were determined to be 47.40, 32.34m 2 /S, 263.97mgKOH/g, 48.22gI 2 /100g and 6.31mgKOH/g respectively. Variations in acid value (AV), viscosity, extent of reaction (R e) and degree of polymerization (D p) of in-process alkyd sample with time were studied. Viscosity, D p and R e increased with time while AV decreased with time. The IR spectra of the test alkyd resin and the commercially prepared alkyd resin showed that the broad band shoulder around 3859.69cm-1 and 3498.02 cm-1 were due to the OH stretch hydroxyl of the unsaturated fatty acid. The peak value within the range of 2930.93 cm-1-2933.83cm-1 observed in both alkyd resins corresponds to SCN and the peak height observed around 1727.31cm-1 was due to CO stretch of unsaturated cyclic ester of monoglyceride. The presence of vinylidene compounds of unsaturated fatty acid of diglyceride and triglyceride were suggested in the peaks observed in both alkyds. From the performance tests, it was observed that the drying trend was faster in CPAR than FWOAR. CPAR showed higher resistant to water and acidic medium than FWOAR and both were poorly resistant to alkaline medium. Results so far obtained from this study suggest that the FWO and FWOAR exhibited good performance characteristics even when FWOAR was compared with the commercially produced alkyd resin and there are similar functional groups in the compounds observed in the absorbance of IR spectra.