Experimental determination of the thermal conductivity of three-phase syntactic foams

Syntactic foams are attractive for applications that require materials with high impact strength and low thermal conductivities. Because syntactic foams are manufactured by dispersing hollow microspheres in a resinous matrix, their characteristics are functions of the type and relative amounts of these materials. In this work, a discussion of an experimental approach to measure the thermal conductivity of three-phase syntactic foams (hollow carbon microspheres in a porous APO-BMI binder, analysis of the data and the comparison to predictive models are presented. The thermal conductivity of three-phase syntactic foams is measured using a Holometrixc steady-state heat flow meter. The experimental data are found to be accurate to within a reasonable range of experimental error and are compared to three of the more reliable predictive models that have been used successfully to estimate the thermal conductivity of similar foams. It is observed that the model predictions at lower temperatures are more accurate as compared to those at higher temperatures. Also, that a model based on the concept of self-consistent field theory better predicts the thermal conductivity of syntactic foams than one based on resistance-in-series. Sensitivity studies indicate a strong dependency of the thermal conductivity of the three-phase foams on the thermal conductivity of the carbon used in the microspheres. C 2006 Springer Science + Business Media, Inc.