Molecular weight control of linear polyethylenes prepared in gas phase with Ziegler catalysts

Linear polyethylenes covering the range from high to low density were prepared in gas phase using an MgCl₂-supported Ziegler catalyst deposited on silica (bisupported catalyst). The comonomer used was 1-butene. Molecular weights are dependent both on 1-butene concentration and hydrogen pressure. The interaction of these two factors can be interpreted by the enhancement of the transfer reactions after 1-butene insertion.