Evaluation of the activity of amine hardeners of epoxy resins

Abstract

With the appearance of new epoxy resins and amines, which are widely used for hardening epoxy compositions using energy-saving technology (at "ordinary" temperatures), on the world market, the targeted selection of these materials to provide the desired technological and operational properties becomes relevant. In order to predictively choose amine hardeners for epoxy resins, their quantum-chemical calculations were performed using the semi-empirical parameterized 3 (PM3) method. The energy value of the highest occupied molecular orbital (HOMO) of amines and the absolute value of the energy gap || (the absolute difference in energies between the HOMO of amines and the lower vacant molecular orbital (LUMO) of epoxy resins) were used. The relationships between the absolute value of the energy gap || and the main technological parameters of the curing process of dian epoxy resin ED-20 with individual amines were established with pairwise correlation coefficients of not less than 0.977. The evaluation of the activity of modified polyamines and their mixtures in hardening epoxy resins is proposed to be carried out based on the maximum temperature of the exothermic reaction of interaction between the epoxy groups of resins and the amine groups of hardeners. The possibility of adjusting the temperature of the exothermic hardening reaction of epoxy compositions and their "viability" time by introducing epoxy-containing diluents with different values of the LUMO energy was shown.