Linear low-density polyethylene/nano-silica composites synthesized 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 mechanical 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 LLDPE-nanocomposite with an exceptional dispersion of nanoparticles throughout the polymer matrix. This is due to the direct linkage 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/SiO[subscript 2]-nanocomposites were synthesized by the in situ polymerization with methylaluminoxane (MAO)/zirconocene catalyst. Two types of SiO[subscript 2] were as the fillers. One type was the SiO[subscript 2] prepared by sol-gel method. The other was the commercial nanopowder silica with two different sizes (10 nm and 15 nm). All particles and the obtained LLDPE/SiO[subscript 2]-nanocomposites were further characterized