The Mechanical Properties of Polyethylene/Clay Nanocomposites Prepared via In-Situ Polymerization Using Bi-Supported Ziegler-Natta Catalysts

In the past decade, researches on the preparation and characterization of organic-inorganic nanocomposites have attracted much academic and industrial attention. Among the nanocomposites investigated, polymer/clay (silicate) systems have exhibited great promise for industrial application due to their positional to display synergistically advanced properties with only minor amount (e.g. 3-5%) of clay loading. The typical enhanced properties include tensile strength, heat deflection temperature, barrier property, and so on [1]. It is worth mentioning that the enhancement of all these characteristics occurs only if the particles are exfoliated or at least intercalated. Intercalation or exfoliation is the result of the incorporation of macromolecules between the layers of the particles [2].PE is the world's highest volume plastic owing to its excellent processability, high volume production, low cost and safety. However, due to the inherent chemical nature, both its stiffness and tensile strength are not always satisfactory. Stimulated by the pioneering advances in Nylon 6 nanocomposites at Toyota research, the intercalation-exfoliation method gets applied to polyolefin materials [3]. For polyolefin, such as PE and PP, which do not include any polar group in their backbone silicate layers even modified by silane coupling agent or grafting polymeric molecules [4], are polar and incompatible with polyolefin [5]. Therefore in situ polymerization, due to clay intercalating or and exfoliating during polymerization, is most effective method to prepare exfoliated PE/clay nanocomposites compared with melt and solution blending methods [6, 7].Today, a Ziegler-Natta catalyst has come to describe any transition metal based catalyst in combination with a main group organometallic cocatalyst for polymerization of polyolefins [8]. In this work we used bi-supported Ziegler-Natta catalyst of TiCl4/MgCl2 (ethoxide type)/clay, to prepared PE/clay nanocomposites. The aim of present article is to study the mechanical, thermal and morphological properties of in-situ prepared PE/clay nanocomposites.