Abstract:The modification of carbon nanotubes and their research on polyurethane compounding have always attracted much attention. In this paper, functional carbon nanotubes covalently grafted with 4,4'-diphenylmethane diisocyanate(MDI) were prepared by the reaction of hydroxy carbon nanotubes(OH-MWCNTs) with MDI. The structural changes of carbon nanotubes before and after modification and the modification effect of MDI@MWCNTs content on the polyurethane elastomer composites was investigated. The experimental results show that the prepared MDI@MWCNTs are endowed with the reactivity of isocyanates. With an increase of MDI@MWCNTs in the polyurethane matrix, the fixed-extension strength monotonically increases, and the elongation at break gradually decreases. When the mass fraction of MDI@MWCNTs is 0.10%, the tensile strength of polyurethane reaches the extreme value (67.4 MPa). Meanwhile, the electrical conductivity of the polyurethane elastomer composites gradually increases, and reaches 1.71 × 10-4 when the added content of MDI-MWCNTs is 0.20%. The novel carbon tubes exhibit excellent reinforcement of polyurethane.