New polyethylene nanocomposites prepared by in-situ nolymeriz tion method usin nickel a-diimine catalyst supported on organo-modified ZnAl layered double hydroxide

New nanocomposites based on polyethylene (PE) and organo-modified ZnAl layered double hydroxide (O-ZnAl-LDH) were prepared by an in-situ polymerization method. The late-transition-metal catalyst, bis(4,4'-methylene-bis-(2,6-diisopropylimino))acenaphthene nickel dibromide complex, was firstly supported on the O-ZnAl-LDH layers and subsequently initiated the polymerization of ethylene. Different from commonly used solution or melt intercalation method, such strategy could induce easily the nanosclae dispersion of the O-ZnAl-LDH layers in the PE matrix, as confirmed by the analyses from X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. From the curves of thermogravimetric analysis (TGA), it was found that the decomposition temperature of the nanocomposite with 12.9 wt% O-ZnAl-LDH could be 60.5 degrees C higher than that of pure PE when 30% weight loss was selected as a measuring point, showing an improved thermal oxidation stability. From the melt theological tests, it was found that the resultant PE nanocomposites had obvious increases in the storage modulus and complex viscosity when compared with pure PE, showing an enhanced viscoelastic response. (C) 2007 Elsevier Ltd. All rights reserved.