Fracture surface analysis on nano-SiO 2/epoxy composite

Abstract

Fracture surface morphologies of nano-SiO 2/epoxy composite with different weight percentage of SiO 2 are investigated using scanning electron microscopy. Two types of curing agent, dimethylbenzanthracene (DMBA) and methyltetrahydrophthalic anhydride (MeTHPA), are individually used for preparing the composites. It is found that the fracture surface morphology of the composite cured by DMBA shows as radial striations, which suggests a rapid brittle fracture mode, while the fracture surface morphology of the composite cured by MeTHPA shows as regularly spaced ‘rib’ markings, which indicates a stick–slip motion during the fracture process. Furthermore, the uniaxial tensile behavior under constant loading rate and ambient temperature are investigated. It is shown that the elastic modulus of the composite cured by DMBA firstly increases, and then decreases with the mass fraction of nano-SiO 2 particles, but the elongation of the composite cured by MeTHPA is reversed with increasing fraction of nano-SiO 2 particles. For nano-SiO 2/epoxy composite cured with MeTHPA that possesses a suitable fraction of nano-SiO 2, an excellent synthetic mechanical property on elastic modulus and elongation is obtained.