The technological aspects of modification of epoxy oligomer DER – 331 to provide improvement of thermophysical characteristics of composite materials and protective coatings based on them are presented. Cold-cured triethylenetetramine TETA hardener was used to crosslink the epoxy binder (q = 10 parts by weight per 100 parts by weight of DER-331 epoxy resin). Thermogravimetric (TGA) and differential thermal (DTA) analysis was performed to study modified composites under the influence of elevated temperatures. A mathematical calculation of the values of the activation energy of thermal destruction to determine the resistance to destruction of chemical bonds under the influence of temperature factor.