All Plant Oil Derived Epoxy Thermosets with Excellent Comprehensive Properties

Epoxidized plant oil (EPO) thermosets usually exhibit poor performance due to the short, brittle, and amorphous cross-link structures. To fabricate fully biobased high performance EPO thermoset, we synthesized dicarboxyl-terminated polyamide1010 (NYL) oligomers from castor oil derived monomers, i.e., sebacic acid and decamethylene diamine, and used the NYL to cure epoxidized soybean oil (ESO) to fabricate all plant oil derived epoxy thermoset through a catalyst-free curing method. Chemorheological study indicated that the curing rate decreases with increasing NYL chain length. The cross-link density of the epoxy thermoset decreases while the crystallization enhances with increasing NYL chain length, which results in drastic enhancement in tensile strength, Young's modulus, and elongation at break of the resultant thermosets, enabling those parameters to enhance by up to 59, 145, and 18 times, respectively, compared to sebacic acid cured ESO thermoset. The melting temperature and thus the heat resistance of the thermosets are also enhanced obviously with increasing NYL chain length. In addition, the thermosets show good durability and excellent thermal stability. With excellent comprehensive properties, the all plant oil derived epoxy thermosets could find some structural applications other than adhesive and coating.