Polyurethane/amino-grafted multiwalled carbon nanotube nanocomposites: Microstructure, thermal, mechanical, and rheological properties

A mixture of two different polyols, (polytetramethylene ether glycol and polydimethylsiloxane), were employed to synthesize a new structure of polyurethane (PU) with methylene diphenyl diisocyanate (MDI) and 1,4-butanediol as chain extender. PU nanocomposites containing variable amount (0.3, 0.5, 1, and 3 wt %) of amino-grafted multiwalled carbon nanotubes (NH2-MWNT) were prepared via in situ polymerization. The dispersion of NH2-MWNT into polymer matrix was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FT-IR) confirmed the urethane-urea chemical bonding between the PU chains and the NH2-MWNT. Thermal stabilities of the nanocomposites were examined with thermogravimetric analysis (TGA) and the results indicated a remarkable improvement with increasing NH2-MWNT contents. The results of dynamic mechanical thermal analysis (DMTA) including storage modulus (E) and glass transition temperature (T-g), as well as tensile properties demonstrated that the yield strength, strain-at-break, and young modulus were enhanced by increasing NH2-MWNT content. Rheological behavior including complex viscosity and storage and loss moduli of the PU nanocomposites improved with increasing NH2-MWNT loading, as well. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44411.