Effect of percolation on the electrical conductivity of amino molecules non-covalently coated multi-walled carbon nanotubes/epoxy composites

The organic amino molecules of tetrazine compound were attached on the surface of multi-walled carbon nanotubes (MWNTs) by non-covalent method, in which amino groups can generate chemical bonding with the epoxide groups in epoxy (EP) matrices. The morphology investigation results showed that the introduction of amino groups on the surface of MWNTs can help MWNTs to disperse homogeneously in EP matrices. The electrical conductivity of the amino-coated MWNTs/EP composites is investigated and its dependence on the content of the MWNT is used to evaluate the percolation threshold of the MWNTs/EP composites. The results showed that the conductivity of the amino coated MWNTs/EP composites was significant higher than that of pristine MWNTs/EP composites at the same MWNT content. The percolation threshold of the amino coated MWNTs/EP composites was 0.13 wt%, while the pristine MWNTs/EP composites were 0.51 wt%. The lower percolation threshold indicates that the introduction of amino groups on the surface of MWNTs can greatly improve the dispersion of MWNTs in EP matrices, which is more important for MWNTs to form an electrically conductive network to enhance the electrical conductivity.