Electrical conductivity and thermal properties of functionalized carbon nanotubes/polyurethane composites

multi-walled carbon nanotubes (mwcnts) functionalized with amine and carboxyl groups were used to prepare polyurethane/mwcnt nanocomposites in two distinct concentrations: a lower value of 1 mass% (spray coating) and a higher one of ~50 mass% (buckypaper based). the mwcnt-nh2 sample contained only 0.5 mass% of amine groups, whereas mwcnt-cooh contained 5 mass% of carboxyl groups. the mwcnt functionalized with low amine group content showed improved thermal properties when compared to neat thermoplastic polyurethane (tpu) and mwcnt-cooh based nanocomposites. the electrical conductivity of the polyurethane elastomer was greatly increased from 10-12 to ~10-5 s cm-1in the 1 mass% nanotube composite and to 7 s cm-1for the mwcnt-nh2 buckypaper-based nanocomposite. furthermore, the relative high content of functional groups in the mwcnt-cooh sample, which disrupt the sp2structure in the nanotube walls, led to inferior properties; for instance the conductivity of the buckypaper based composite is one order of magnitude lower when using mwcnt-cooh in comparison with the mwcnt-nh2. these results show the range of property design possibilities available with the elastomeric polyurethane nanocomposite by tailoring the functional group content and the carbon nanotube load.