Abstract:In order to improve the tensile strength of basalt fiber/epoxy (BF/EP) composites, silane coupling agent KH550 was grafted on the surface of BF for enhancing the interfacial strength between BF and EP matrix. The effects of KH550 grafting degree on the surface roughness of BF, the interfacial adhesion between BF and EP matrix and the tensile strength of composites were investigated by attenuated total reflection infrared spectroscopy, X-ray photoelectron spectrometer, atomic force microscopy, scanning electron microscopy, droplet microdebond test and tensile test. Experimental results show that grafting KH550 on the surface of BF reinforces the interface roughness and interfacial strength of KH550-BF/EP composites. With the increase of KH550 grafting degree, the surface morphologies of BF change from smooth to rough, then to smooth, final to rough. Meanwhile, the interfacial strength and tensile strength of composites are also increased firstly, and then reduced. When the KH550 grafting degree reaches about 5%~6%, the surface of BF is smooth, uniform and non-aggregated. And the interfacial strength and tensile strength reach the maximum values of 48 MPa and 298 MPa, respectively. When the KH550 grafting degree exceeds 6%, the surface morphology of KH550-BF becomes non-uniform. Excessive KH550 brings structural defects and stress concentration to the interface, which deteriorates the interface strength as well as the tensile strength of composites.