Compression properties of syntactic foams: effect of cenosphere radius ratio and specimen aspect ratio

The present work is aimed at characterizing syntactic foams for flatwise (specimen aspect ratio of 0.5) properties and investigating the effect of change in the internal radius of cenospheres. The density and mechanical properties of the syntactic foam can be changed while keeping cenosphere volume fraction and particle-matrix interfacial area the same by using cenospheres of same outer radius but different inner radius. Five types of cenospheres, with the same mean outer radius but a different internal radius, have been selected for the fabrication of syntactic foams. ASTM C 365-94, a standard for the flatwise compressive properties of sandwich cores, is followed in the present work. The results obtained in the study are compared with the results of edgewise (specimen aspect ratio of 2) compressive properties evaluated in earlier work. Results show an increase in compressive strength and modulus with decrease in internal radius of cenospheres. The peak compressive strength and modulus were measured to be higher for the specimens tested in flatwise orientation compared to that in edgewise orientation. Varying only one parameter, the internal radius of cenospheres, helped in understanding the role of cenospheres and matrix resin in deformation and fracture process of syntactic foams. (C) 2004 Elsevier Ltd. All rights reserved.