Degradation kinetics of epoxidized soybean oil

Abstract

AbstractThis work deals with the degradation kinetics of epoxidized soybean oil, whereas the weight loss of epoxidized soybean oil (ESO) cured with methyl tetrahydrophthalic anhydride (MTHPA) as hardener and 2,4,6‐tris (dimethylaminomethyl) phenol (DEH 35) as catalyst displayed two main regions in the thermogravimetry (TG) plots. Nevertheless, deconvolution of the weight loss plots presented three or more events depending on the composition and experimental parameters. Increase the MTHPA addition led to a decrease in the activation energy (AE) for curing which conducted to an increased AE during the degradation. Friedman's isoconversional model exhibits proper R2 for the curing kinetics, but lower R2 values for lower anhydride contents during the degradation kinetics analyses. Kissinger‐Akahira‐Sunose (KAS) and Ozawa‐Flynn‐Wall (OFW) models displayed the best R2 during the kinetics evaluation, whereas the degradation mechanisms fitted reasonably with Avrami‐Erofeev (An) and nth‐order autocatalytic (Cn) during the first and second weight loss regions. Microstructural analyzes and in‐depth investigations into the thermal degradation mechanism of ESO suggest two possible pathways, that is, production of carbonic groups through heterolytic scission, and formation of electrically stable groups with saturated carbon bonds.