Synthesis of linear low-density polyethylene (LLDPE) / Alumina nano composite via in situ polymerization with metallocene catalysts

Abstract

It is known that linear low-density polyethylene (LLDPE) can be synthesized by copolymerization of ethylene and 1-olefins using metallocene catalysts. However, the properties of LLDPE can be improved by adding organic or inorganic fillers. It should be mentioned that by adding nanoscale fillers into LLDPE, LLDPE-nanocomposites can be achieved. Among methods to produce polymer nanocomposites such as solution blending, melt mixing process and in situ polymerization, the in situ polymerization is perhaps the most promising method to produce the LLDPE-nanocomposite with an exceptional dispersion of nanoparticles inside the polymer matrix. This is due to the direct lingkage of active centers to the surface of nanoparticles. Therefore, it is necessary to immobilize the active centers onto nanoparticle surface or fillers. In this present study, LLDPE/Al[subscript 2]O[subscript 3] – nanocomposites were synthesized by the in situ polymerization with dried-modified methylaluminoxane (d-MMAO)/zirconocene catalyst. The nano-Al[subscript 2]O[subscript 3] was commercially obtained from Aldrich. The amounts of nanomaterials filled were also varied. Yields, activities, and polymer morphologies were discussed. It was found that the polymerization activity strongly depended on the [Al][subscript d-MMAO]/[Zr] ratios. The samples were further characterized using SEM/EDX, DSC, [superscript 13]C NMR, and GPC.