Thermal properties, curing characteristics and water absorption of soybean oil-based thermoset

Epoxidized soybean oil (ESO) was successfully thermal-cured by using methylhexahydrophthalic anhydride (MHHPA) curing agent, in the presence of tetraethylammonium bromide (TEAB) catalyst of varied concentration (0.3-0.8 phr).The polyesterification process of ESO thermoset was proven and supported by Fourier transforms infrared spectroscopy (FTIR) and gas chromatography-mass spectroscopy analysis (GC-MS).A possible chemical reaction of the MHHPA, TEAB and ESO was proposed based on the experimental work.Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) revealed that there is a positive relationship between the degree of conversion and crosslink density of ESO thermoset with TEAB concentration.The kinetics of water absorption of the ESO thermoset were found to conform to Fickian law behavior.