Influence of a batch of hollow glass microspheres with different strength grades on the compression strength of syntactic foam

Nowadays, syntactic foam filled with hollow glass microspheres (HGM) has been widely used in aeronautical and marine structural applications. In order to obtain a lightweight and high strength syntactic foam, a batch of HGM is usually filled into a resin matrix at a high-volume percentage. Therefore, the strength of syntactic foam was largely dependent on the strength of HGM. In general, a batch of HGM is usually composed of many individual glass microspheres with different true densities, particle sizes, and wall thicknesses, result in differences of the strength, which may lead to the difference in failure mechanism of syntactic foam. However, the strength distribution of a batch of HGM and its influence on the compression strength of syntactic foam has rarely been studied. In this work, the T30-P HGM were obtained by a batch of T30 HGM under five grades isostatic pressure P (P = 10, 20, 30, 40, 50 MPa) treated then floatation. Afterwards, the T30-P HGM were respectively incorporated into epoxy resin E51 with volume fraction of 70% to fabricate syntactic foams SF-T30-P. The results indicated that the compression strength of the syntactic foams was improved from 35.3 MPa to 49.8 MPa nonlinearly with the increasing strength of T30-P HGM. The failure mechanism of the syntactic foams was analyzed and the recommendations for preparing syntactic foams with optimal strength were proposed.