Solvation effect of CO2 on accelerating the curing reaction process of epoxy resin

Abstract

The solvation effect of compressed CO2 on the curing reaction process of epoxy resin was investigated by using the in-situ FTIR. The isothermal curing kinetic constant and activation energy of diglycidyl ether of bisphenol A (DGEBA) with m-xylylenediamine (MXDA) was calculated via Kamal autocatalytic model. The autocatalyzed rate constants and activation energy under 0.1 MPa CO2 are 0.7139 min−1 and 50.83 kJ/mol at 393 K, while those under 18 MPa CO2 are 1.0928 min−1 and 36.36 kJ/mol, respectively. The increased kinetic constant and reduced activation energy suggests that the plasticization effect of CO2 eases the chain movement, promotes the curing of epoxy resin, and increases the final conversion at relatively low temperature. Then, an amended Kamal model involving the diffusion factor was applied to better describe the curing process, which suggests that the high pressure CO2 plays an important role to reduce the mass transfer resistance and intensify the curing process. Meanwhile, the activation energy determined by the isoconversional method, also decreases with CO2 pressure at the same conversion. Especially, the activation energy at 90% conversion under 0.1 and 18 MPa CO2 are 46.52 and 36.19 kJ/mol, respectively, which further confirms the solvation effect of CO2 accelerates the curing of epoxy resin.