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.