Mechanical properties of silica-coated multi-walled carbon nanotube/epoxy composites

Multi-walled carbon nanotubes (MWCNTs) were coated with silica layers via a one-step sol-gel process with tetraethyl orthosilicate (TEOS) as a silica precursor to enhance the mechanical strength and electrical resistivity of MWCNTs-filled epoxy composites. The MWCNTs were coated uniformly with silica using polyethyleneimine as a coupling agent without chemical modification of the surface of the MWCNTs. The silica-coated MWCNTs were used as a filler in the epoxy. The epoxy composites filled with the raw and silica-coated MWCNTs were prepared and their properties were examined in tenns of mechanical, thermal and electrical properties. The epoxy chains were bound strongly to the silica layer on the surface of the MWCNTs, and the silica layer provided the MWCNTs with electrically insulating barriers. As a result, the silica-coated MWCNTs-filled epoxy composites showed improved mechanical strength and electrical resistivity.