Effect of the Grafted Silane on the Dispersion and Orientation of Clay in Polyethylene Nanocomposites

The CTAB ammonium intercalated montmorillonite clay, CMT, was modified by an alkylsilane, Dodecyltrimethoxylsilane, to improve the miscibility of organo-clays with PE matrix, involving the grafting reaction between the silane and silanol groups on the edge of clay. The silane modified clays (DMT) exhibited improved thermal stability due to the replacement of the physically adsorbed ammonium by the covalently bonded silane. The clays were melt compounded with polyethylene. Compared with the composite of PE/CMT, the clay dispersion state was improved, and a unique orientation of the clay layered was observed in PE/DMT nanocomposites, which was confirmed by XRD and TEM studies. The dispersion state, orientation degree of clay and, as a result, the mechanical and thermal properties of the nanocomposites were enhanced with the increasing amount of the grafted silane, indicating that the edge grafting of silane played a crucial role in controlling the structure and properties of nanocomposites. POLYM. COMPOS., 30:1234-1242,2009. (C) 2008 Society of Plastics Engineers