Synthesis of linear low density polyethylene/titania nanocomposites with zirconocene catalyst by in situ polymerization of ethylene/1-hexene

Abstract

Because of the commercial interest of using metallocene catalysts for olefin polymerization, it has led to an extensive effort for utilizing metallocene catalysts more efficiently. It is known that linear low-density polyethylene (LLDPE) can be synthesized by copolymerization of ethylene and 1-olefins using metallocene catalysts. However, it was found that homogenization of metallocene has two major disadvantages; the lack of morphology control of polymers produced and reactor fouling. Therefore, heterogenization of metallocene was brought to solve these problems. Polymers filled with inorganic nanoparticles as nanofillers are recognized as polymer nanocomposites. It can be produced via the in situ polymerization with the presence of nanofillers added during synthesis by the application of supported metallocene catalysts. The effects of different nanofillers on the properties of polymers are different. The most commonly used nanofillers such as SiO2, TiO2, Al2O3, and ZrO2 were studied. Among the methods to produce polymer nanocomposites, the in situ polymerization is perhaps the most promising method to produce LLDPE-nanocomposite with an exceptional dispersion of nanofillers 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 nanofiller surface. In this present study, LLDPE/TiO2 nanocomposites were synthesized by the in situ polymerization with dried modified methylaluminoxane (dMMAO)/zirconocene catalyst. The TiO2 nanofillers having different phases were employed. All nanoparticles and the obtained LLDPE/TiO2 nanocomposites were further characterized using various techniques.