Characterization of epoxy foams

Epoxy foams were prepared from the commercial system (LY 5054 epoxy resin, HY 5054 amine as curing agent, and DY 5054 siloxane as foaming agent) supplied by Ciba-Geigy. From the differential scanning calorimeter results the optimal epoxy-amine ratio was determined. A maximum T-ginfinity value of 85degreesC was found for an epoxy-amine ratio of 100:35 by weight. In this system, the siloxane reacts with the amine releasing hydrogen that acts as the real foaming agent. The density decreased from 490 to 215 kg/m(3) as the epoxy:blowing agent ratio increased from 100:1 to 100:3 by weight of the reactive mixture. Under the synthesizing conditions, the glass transition temperature (T-ginfinity) of the foam did not vary significantly as the blowing agent increased. The modulus and compressive strength of the foam exhibited a power-law dependence with respect to density of the form: E-infinity(rho)(n), where n=1.8. Scanning electron microscopy analysis verified that the foam have a closed cell structure. The relation between composition, final morphology, density, and properties of the foam was analyzed. (C) 2003 Wiley Periodicals, Inc.