Characterisation of rapeseed oil based resins using infrared and thermogravimetry techniques
Keywords:Triglycerides, hydroxylation, cure, polyurethane, characterisation
Rapeseed oil which is a triglyceride had undergone chemical modification on its structure to obtain hydroxyl groups. The hydroxylated chemical structure was crosslinked using methylene-pphenyl diisocyanate to produce a thermoset rapeseed oil resin. The cross linking process was monitored in situ using the Attenuated Total Internal Reflectance Fourier Transform-Infrared spectroscopy and the thermogravimetric analysis techniques. The infrared technique was also used to monitor chemical groups of the unmodified rapeseed oil. A reduction of the absorption band around 3300 cm-1 which is due to the presence of hydroxyl groups was observed indicating the occurrence of the reaction between the hydroxylated rapeseed oil and methylene-p-phenyl diisocyanate. The thermogravimetric analysis technique recorded the reduction of the hydroxyl groups as the loss in mass of the reactants as a function of temperature. The two analytical techniques provided about the same cure time. Both, the infrared and thermogravimetric techniques elucidated useful cure characteristics of the rapeseed oil resin. The applications of more than one analytical method offer a complement of the results.