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

Syntactic foams are a class of lightweight composites synthesized by dispersing hollow particles (microballoons) in a matrix material. These materials have found extensive use in underwater oil exploration equipment and submarine structures due to their outstanding compressive properties and tailorable buoyancy. In the majority of present applications and existing studies, these foams are fabricated using microballoons composed of soda-lime glass. However, sodium ions can leach out of the glass particle and cause disintegration of the particle wall when such foams are exposed to moisture for prolonged periods, as in the current applications. This reduces the structural integrity of the foam and permits water to fill the voids in the composite. In this work, syntactic foams are fabricated using borosilicate glass particles, which do not show degradation upon moisture exposure. The fabricated syntactic foams are tested for compressive properties at quasi-static and high strain rates. The compressive strength was observed to increase with increasing wall thickness of microballoons and decreasing particle volume fraction. The compressive strength increased by up to 90% at high strain rates compared to quasi-static, but no strain rate sensitivity was observed in the range of 750-1750/s.