Fully biobased and high performance epoxy thermosets from epoxidized soybean oil and diamino terminated polyamide 1010 oligomers

Abstract

Fully biobased and high performance epoxy thermosets were synthesized through curing of epoxidized soybean oil (ESO) with crystalline diamino terminated polyamide 1010 oligomers (OPAs). Four OPAs with different molecular weights were prepared to cure ESO. The results of isothermal curing investigation indicated that the curing rate decreased with increasing molecular weight of the OPA. The effects of chain length of OPAs on the thermal transition, crystallization behavior mechanical properties, heat resistance and thermal stability of the ESO thermosets were investigated in detail. The results showed that the crystallization was significantly enhanced, the glass transition temperature and the melting temperature increased to a higher temperature range with increasing OPA chain length. The tensile strength, Young's modulus, storage modulus and elongation at break increased considerably with increasing OPA chain length, due to the gradually enhanced network stiffness through crystallization and reduced crosslink density through increasing chain length between crosslinking sites. The heat resistance of the thermosets was also enhanced with increasing OPA chain length due to the increased melting temperature of the thermoset. In addition, the biobased epoxy thermosets showed excellent thermal stability with onset decomposition temperature of higher than 330 °C.