Effects of hollow microsphere surface property on the mechanical performance of high strength syntactic foams

Abstract Syntactic foams (SF) with robust impermeable hollow microspheres as density adjuster have drawn much attention because of their easy-tailored low density, high mechanical strength and excellent performance especially when used in high pressure aqueous environment. In this work, specially fabricated hollow silicate glass microspheres (HSMs) with high strength to weight ratio were employed for the controlled fabrication of high strength lightweight syntactic foams. Special attention has been paid on the effects of surface physicochemical status modification of the HSMs on the mechanical strength and mechanical performance evolution in various external environments. It is found that the surface physicochemical status modification of the HSMs contributes more on the enhancement of the fracture toughness compared with that of the compressive strength. Moreover, compared with those of the pristine SF, the mechanical strength of the SF samples after different environmental exposure display a more remarkable improvement due to the surface physicochemical status modification of the HSMs, indicating an enhanced environmental stability. This work provides an additional insight to the mechanical strength and aging resistance control of SF, which holds the potential to be extended to the property improvement of similar composites with various types of silicate or glass fillers.