International. A group of researchers wants to develop a thermoset of epoxidized vegetable oil with a biological base. Epoxy thermosets are used as adhesives and coatings in electronics, appliances, and airplanes, but most of them are not environmentally friendly. Oil thermosets from epoxidized plants are usually weak and break easily.
The researchers synthesized polyamide 1010 (Nyl) oligomers terminated in dicarboxyl from monomers derived from castor oil, i.e. sebacic acid and decametilen diamine, and used Nyl to cure epoxidized soybean oil (ESO) to manufacture the entire thermoset of vegetable oil-derived epoxy through a catalyst-free curing method.
The chemologic study indicated that the curing rate decreases with increasing length of the Nyl chain. The cross-linking density of the epoxy thermoset decreases while the crystallization improves with the increase in the length of the Nyl chain, resulting in a drastic improvement in tensile strength, Young's modulus and elongation at breakage of the resulting thermosets, allowing those parameters to increase by up to 59, 145 and 18 times, respectively, compared to the ESO thermoset cured with sebacic acid.
The melting temperature and therefore the heat resistance of the thermosets are also obviously improved by increasing the length of the Nyl chain. In addition, thermosets show good durability and excellent thermal stability. With excellent comprehensive properties, all epoxy thermosets derived from vegetable oils could find some structural applications other than adhesives and coatings.
Source: http://pubs.acs.org/doi/abs/10.1021/acs.macromol.7b01068
