Experimental design as a route for improving the performances of formulated epoxy adhesives

Abstract Experimental design was used to put in order the formulation factors of an epoxy adhesive. The influence on the reactivity (ΔH), the glass transition ( T g ) and mechanical performances ( R m ) of factors such as the nature of the epoxy, the hardener, the plasticizers, fillers, and cure promoter, was investigated by DSC and the three point flexure test. A high reactivity is provided by the DGEBA resin coupled to the DETA hardener and a reactive plasticizer. The glass transition is mainly influenced by the nature of the hardener and the presence of the plasticizer. The maximal strain recorded on aluminum and steel is improved by the DGEBA/polyamide hardener with a slight excess of epoxy resin, while the EPN/DETA system must be used with respect to the stoichiometric composition.