Mechanical properties of epoxy matrix-borosilicate glass hollow-particle syntactic foams

Syntactic foams are particulate composites, which consist of a dispersion of hollow particles in a matrix. These materials are extensively used in the structures of underwater vehicles, but existing studies have shown that the commonly used soda-lime-borosilicate glass hollow particles are susceptible to significant degradation upon exposure to moisture. In this work, epoxy matrix syntactic foams are fabricated using borosilicate glass hollow particles that are not susceptible to degradation in wet environments. Nine compositions are fabricated and tested for quasi-static compressive properties, high-strain-rate compressive properties, and flexural properties. The quasi-static compressive strength and energy absorption are found to increase with composite density and the compressive strength is found to exceed that of similar syntactic foams using soda-lime-borosilicate hollow particles. The syntactic foams were observed to have 70 %-108 % higher peak stress in the high-strain-rate regime compared to the quasi-static values but the strength within the high-strain-rate regime was not dependent on the strain rate. The flexural properties were shown to have strong sensitivity to volume fraction of hollow particles.