Cure kinetics of an epoxidized hemp oil based bioresin system

Abstract

A novel epoxidized hemp oil (EHO) based bioresin was synthesised by epoxidation in situ with peroxyacetic acid. In this research the cure kinetics of an EHO based bioresin system cured with Triethylenetetramine (TETA) was studied by Differential Scanning Calorimetry (DSC) using both isothermal and non-isothermal data. The results show that the curing behaviour can be modelled with a modified Kamal autocatalytic model that accounts for a shift to a diffusion-controlled reaction post-vitrification. The total order of the reaction was found to decrease with an increase in temperature from approximately 5.2 at 110°C to approximately 2.4 at 120°C. Dynamic activation energies were determined from the Kissinger (51.8 kJ/mole) and Ozawa-Flynn-Wall (56.3 kJ/mole) methods. Activation energies determined from the autocatalytic method were 139.5 kJ/mole and -80.5 kJ/mole. The observed negative activation energy is thought to be due to an unidentified competitive reaction that gives rise to the appearance of decreasing with increasing temperature. The agreement of fit of the model predictions with experimental values was satisfactory for all temperatures.