Solvation effect of CO2 on accelerating the curing reaction process of epoxy resin
The solvation effect of compressed CO 2 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 CO 2 are 0.7139 min −1 and 50.83 kJ/mol at 393 K, while those under 18 MPa CO 2 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 CO 2 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 CO 2 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 CO 2 pressure at the same conversion. Especially, the activation energy at 90% conversion under 0.1 and 18 MPa CO 2 are 46.52 and 36.19 kJ/mol, respectively, which further confirms the solvation effect of CO 2 accelerates the curing of epoxy resin.
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