MORPHOLOGY AND THERMO-MECHANICAL RESPONSE OF POLYURETHANE NANOCOMPOSITES CONTAINING HYPERBRANCHED POLYMER

摘要

Novel polyurethane (PU) was derived from -NCO terminated polyurethane prepolymer and third generation hyperbranched polyester polymer (HBP) and the effect of layered silicate on this PU was studied. An apparent microphase-segregated morphology of the pristine polymer and its nanocomposites was observed by transmission electron microscopy (TEM) and atomic force microscopy (AFM).These also revealed regions of exfoliation and intercalation in the case of nanocomposites, which were further confirmed by X-ray diffraction (XRD) analysis. The nanocomposite containing 8 wt% clay loading showed -139% increase in tensile strength along with dramatic improvement in thermal and dynamic mechanical properties over the control PU. It was also found from Fourier transform infrared spectroscopy analysis that the extent of tethering reactions between the polymer chains carrying residual -NCO groups and the reactive HBP was significant and the nanofiller reacted mostly with -NCO containing prepolymer. Key words: Polyurethane, nanocomposite, hyperbranched polyester polymer.