Journal of Applied Polymer Science, Vol.89, No.1, 91-95, 2003
Novel moisture-curable epoxy resins and their characterization
The shelf-life stability and curability of a moisture-curable epoxy resin system were evaluated with ketimines, which were used as moisture-latent hardeners and were derived from different kinds of ketones as protective groups. Both the shelf-life stability and curability of the compounds were mainly influenced by the steric hindrance of the ketimines. The theoretical results calculated by MOPAC showed good agreement with the experimental results. Methyl i-propyl ketone and methyl t-butyl ketone, having a narrow space (<4.2 Angstrom) around ketimine N and a wide space (>3.7 Angstrom) around ketimine C, were demonstrated to be the optimum ketones for the ketimines. The lap shear strength, with respect to the adhesive properties of the ketimines, was higher with a large-volume ketone than with a small-volume ketone as the protective group. This was due to the higher reaction conversion of the epoxide for the system. hi addition, the large plasticizing effect of the large ketone volume could lead to a large relaxation of the stress generated at the bonding interface. (C) 2003 Wiley Periodicals, Inc.