Preparation and Characterization of Polyurethane/Multiwalled Carbon Nanotube Composites

Multiwalled carbon nanotube (MWNT)/polyurethane (PU) nanocomposites have been prepared by the combination of in-situ polymerization and solution-casting approach. A homogeneous dispersion of MWNTs throughout PU matrix is observed by scanning electron microscopy on the fracture surfaces of the composites. Strong interfacial adhesion between the MWNTs and the PU matrix, as evidenced by the presence of broken but strongly embedded MWNTs in the matrix, is favorable to stress transfer from polymer matrix to the nanotubes. Mechanical tests (by tensile testing and dynamic mechanical analysis) show that, compared with neat PU, both the Young's modulus and the tensile strength of the composites are significantly improved by about 90%, with incorporating only 1 wt.% MWNTs. And most importantly, the elongation-at-break of PU/carbon nanotube (CNT) composites is greatly improved by about 500%, indicating that the toughness of neat PU is remarkably enhanced by adding CNTs into the matrix. The fine dispersion of CNTs and strong interfacial adhesion between the CNTs with the matrix are responsible for the simultaneous and significant enhancement in the strengthening and toughening of PU matrix. In addition, the thermal stability of PU was also improved after incorporating CNTs into the matrix.