Epoxy compositions and materials cured with complexes of imidazoles and Cu(II) cations

The compositions of Epidian 6 epoxy resin cured with latent hardeners: complexes of imidazoles [2-methylimidazole (2M) or 2-ethyl-4-methylimidazole (2E4M)] with Cu(II) cations, or for comparison with Mg(II) cation and non-complexed 2M or 2E4M imidazoles (Table 1), were prepared. Pot lifetime and thermal parameters characterizing curing process, namely enthalpy and temperature of maximum heat effect (Table 1 and 2, Fig. 1) were investigated. The use of complexes of imidazoles with Cu(II) cation shifts this temperature upward 35-49°C and extends pot lifetime of the composition at ambient temperature even 30 times. Static mechanical properties at tension and bending of casts made of the compositions discussed were determined (Table 3 and 4). Shear strength of adhesive joints based on the compositions has been evaluated. Shear strength at room temperature does not depend on curing agent type. However, at temp. 120°C complexes of latent hardeners let reach much better shear strength than that caused by non-complexed imidazoles, especially 2M (Table 5).