Ethylene Polymerization, On-Line Particle Growth Monitoring, and in Situ Nanocomposite Formation Using Catalysts Supported on Arylsulfonic Acid-Modified Boehmites

Ethylene was polymerized on Cp 2 ZrCl 2 activated by methylalumoxane (MAO) supported on boehmites modified with arylsulfonic acids. In comparison with unmodified boehmites, boehmites modified with arylsulfonic acids gave significantly higher MAO uptakes. Cp 2 ZrCl 2 activated with arylsulfonic acid-modified boehmites/MAO gave notably higher catalyst activities compared with those of homogeneous Cp 2 ZrCl 2 /MAO and Cp 2 ZrCl 2 activated with unmodified boehmite/MAO and SiO 2 /MAO. According to 13 C CP-MAS NMR investigations of MAO supported on p-toluenesulfonic acid-modified boehmite, partial alkylation of p-toluenesulfonate by MAO accounted for the formation of methyl p-tolyl sulfone as an electron-donating catalyst modifier. Polymer particle morphologies and size distributions were examined off-line by means of scanning electron microscopy, light scattering on dry powder dispersions, and CCD-mediated powder particle image analysis. The mechanism of polymer particle formation via deagglomeration of boehmite particles was elucidated by means of on-line monitoring using focused beam reflectance measurement. As evidenced by transmission electron microscopy, polyethylene particles contained uniformly dispersed boehmite crystallite aggregates with average diameters of 100 nm.