Epoxy resin nanosuspensions and reinforced nanocomposites from polyaniline stabilized multi-walled carbon nanotubes

The high performance multi-walled carbon nanotubes (MWNTs) reinforced epoxy polymer nanocomposites (PNCs) have been synthesized at different MWNT loading levels. The surface functionalization of MWNTs with conductive PANI was achieved by using a facile surface initiated polymerization method with the aid of the oxidations of CNTs and subsequent anilines by hexavalent chromium (Cr(VI)) oxidant. The effects of MWNT loading, surface functionalization and temperature on the rheological behaviors of liquid epoxy resin nanosuspensions and on the physicochemical properties of cured solid PNCs were systematically investigated. The glass transition temperature (T-g) of the cured epoxy PNCs filled with functionalized MWNTs obtained from the dynamic mechanical analysis (DMA) test was increased about 6-25 degrees C than that of cured pure epoxy. The PNCs reinforced with functionalized MWNTs demonstrated an enhanced tensile strength than either cured pure epoxy or its PNCs filled with the as-received MWNTs. The electrical conductivity of cured epoxy PNCs with functionalized MWNTs was improved by 5.5 orders of magnitude compared with cured pure epoxy. Thermogravimetric analysis (TGA) revealed an enhanced thermo-stability in the cured epoxy PNCs filled with functionalized MWNTs than that of cured pure epoxy and its PNCs filled with the as-received MWNTs. The observed strong interfacial interaction between MWNTs and the epoxy resin matrix was responsible for the enhanced mechanical tensile strength. The nanocomposite formation mechanism is proposed based on the analysis from Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), Raman and differential scanning calorimetry (DSC) tests.