Structure characteristics and thermal properties of silane-grafted-polyethylene/clay nanocomposite prepared by reactive extrusion

Silane-grafted-polyethylene/OMT nanocomposite (VTMS-g-PE/OMT) was prepared by reactive extrusion from linear low density polyethylene (LLDPE), vinyltrimethoxysilane (VTMS), organically modified montmorillonite (OMT) and dicumyl peroxide (DCP). A series of tests such as X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transfer infrared (FTIR) and thermogravimetric analysis (TGA) have been performed to characterize the morphology and thermal properties of the graft polymer and its nanocomposite. Results show that the graft polymer (VTMS-g-PE) chains have been successfully intercalated into OMT layers proved by XRD data (a d-spacing of 3.4 nm) and TEM images; the PE chains have been chemically bounded to the OMT layers proved by FTIR spectra; the nanocomposite exhibits a higher thermal-oxidative stability than that of either the VTMS-grafted-LLDPE or the LLDPE proved by TGA curves. The increase in thermal properties lies in two facts: one is the formation of chemical bonds between PE macromolecules and OMT layers during silane graft reaction; the other is the in situ graft of PE macromolecules onto the OMT surfaces during thermal-oxidative degradation.