Studies in metallocene polymerizations

• Main Author: Walshe, Darren
• Published: University of Manchester 2001
• Subjects: 547.28
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616905

Metallocene catalysts can give polyolefins at high activity and with novel structure but need to be supported to be used in modem polymerization processes. The present thesis sought to improve the understanding of supported metallocene catalysts for propylene polymerization through examination and attempted optimisation of the steps involved in catalyst preparation in order to give the maximum activity with least leaching of catalyst from the support. Initially, supported catalysts of the type Si02IMAO/ [MAO + EtInd2ZrChl were made. Lower loadings of aluminium appeared to lead to the most active catalysts. In the first part of the work, adsorption isotherms were obtained for a microspheroidal, high pore volume silica (MS3050 from the PO Corporation) and a granular silica (EPIOX f~m Crosfields). The effects of temperature volume and solvent were examined. It was found that the MS silica could adsorb considerably more MAO than the EP silica (over twice as much). A limit of adsorption was observed for the EPI OX, but not the MS3050. In both cases, less CoMAO in heptane could be adsorbed onto the two silicas than MAO in toluene.