Influence of hollow carbon microspheres of micro and nano-scale on the physical and mechanical properties of epoxy syntactic foams

Abstract

Epoxy syntactic foams were prepared by introducing hollow carbon microspheres (HCMs) of micro and nano-scale. Based on the surface structure analysis of the HCMs, the effects of HCM content and particle size on the mechanical properties, dimensional stability, thermal conductivity, thermal stability and dielectric properties of the epoxy foam were investigated. The density of the epoxy foam gradually declined with the increase of the micro-scale HCM (M-HCM) content up to 9 wt%, and the compression strength of the epoxy foam just decreased slightly, while the compression modulus and flexural modulus were enhanced continuously. When 0.5 wt% and 1 wt% of HCMs were involved, the reinforcing effect of nano-scale HCMs (N-HCMs) was superior to the M-HCMs. The compression strength of the N-HCM/epoxy foams was almost equivalent to the neat epoxy, while the flexural strength of the N-HCM samples exhibited an obvious superiority. The dimensional stability and thermal stability of the epoxy foams were also improved with the addition of HCMs. Besides, the introduction of the M-HCMs and N-HCMs gave rise to different effects on the thermal conductivity, electrical conductivity and dielectric constant of the resulting epoxy foams due to the diversity in the interfacial interactions and microstructure. These results indicate that the HCM/epoxy syntactic foams show potential for application in multifunctional materials that are lightweight and of high rigidity.