Abstract
The curing of epoxy resin was studied using the aluminum acetylacetonate (Alacac3) - phenols catalyst system. First, cyclohexene oxide (CHO) was polymerized 160°C as a model compound of epoxy resins.1H-NMR and IR spectra showed that the polymer contained hydroxy and phenoxy end groups. In the curing of 3, 4- epo-xycyclohexylmethyl 3, 4- epoxycyclohexanecarboxylate (Celoxide 2021) a linear relationship between the curing of Celoxide 2021 and the dissociation constants of phenols was observed in the Alacac3-p- substituted phenols (p-RPhOH, R=NO2, Cl, H, Me, OMe) catalyst system. The introduction of a electron- attracting group into benzene ring accelerated the curing rate and vice versa. The active species was estimated as the following structure, based on the end group analysis of polymer, the reaction of Alacac3 and phenols, and the curing rate dependence on the acidity of phenol.
Then the curing of epoxy resin in the Alacac3- phenols catalyst is thought to proceed in the cationic polymerization mechanism.
