Study on curing kinetics of epoxy system and DFT simulation

Epoxy asphalt has emerged as a high-performance pavement material. However, research on its curing mechanism and kinetics remains limited. This study aimed to investigate the kinetic equation of the epoxy asphalt curing system using non-isothermal differential scanning calorimetry for better understanding and prediction of the curing reaction. The results revealed that the epoxy asphalt system in this study is autocatalytic, with the conversion rate increasing as the heating rate rises. Additionally, this research employed Density Function Theory to simulate the surface electrostatic potential distribution of the curing agent and epoxy resin in epoxy asphalt. This approach identified potential active sites for chemical reactions, confirming the likelihood of a cross-linking reaction between carbon-carbon double bonds in the oleylamine curing agent. This cross-linking reaction contributes to the formation of a network structure in the cured epoxy resin system, resulting in superior mechanical properties for the cured epoxy asphalt. The study utilized transition state theory to simulate the ring-opening reaction between the primary amine group in oleylamine and epoxy resin. Finally, the above conclusions were verified using in situ infrared spectroscopy, and the microstructure of the epoxy asphalt at different curing times was observed using in situ fluorescence microscopy. In conclusion, this research provides valuable insights into the curing mechanism and kinetics of epoxy asphalt, offering guidance for future applications and development in the field of pavement materials.