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Polypropylene and ethylene-propylene copolymer reactor alloys prepared by metallocene/ziegler-natta hybrid catalyst / Lie Lu in Industrial & engineering chemistry research, Vol. 48 N° 18 (Septembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8349–8355 Titre : Polypropylene and ethylene-propylene copolymer reactor alloys prepared by metallocene/ziegler-natta hybrid catalyst Type de document : texte imprimé Auteurs : Lie Lu, Auteur ; Hong Fan, Auteur ; Bo-Geng Li, Auteur Année de publication : 2010 Article en page(s) : pp. 8349–8355 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polypropylene  Ethylene−propylene  rubber  reactor  Propylene  homopolymerization  Metallocene  activation  Ethylene−propylene  copolymerization Résumé : Polypropylene/ethylene−propylene rubber (PP/EPR) reactor alloys were prepared with a metallocene/Ziegler−Natta hybrid catalyst system (rac-Et(Ind)2ZrCl2/TiCl4/MgCl2) using a process composed of three stages: propylene homopolymerization, metallocene activation, and ethylene−propylene copolymerization. A series of alloy samples were produced and characterized at various copolymerization conditions by varying the methylaluminoxane (MAO)/Zr ratio and monomer composition. It was shown that the metallocene/Ziegler−Natta hybrid system exhibited the features of both metallocene and Ziegler−Natta catalysts during copolymerization. The hybrid catalyst had better ability in incorporating α-olefin than the Ziegler−Natta catalyst owing to the action of metallocene active sites. DSC and IR analyses suggested that EPR in the alloys became random with increased MAO/Zr ratio. In addition, reducing the ethylene content in the feed decreased the activity and promoted the production of random copolymers. An operation window of reaction conditions was identified for the preparation of well-dispersed spherical PP/EPR reactor alloy particles containing up to about 40 wt % EPR. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900579h [article] Polypropylene and ethylene-propylene copolymer reactor alloys prepared by metallocene/ziegler-natta hybrid catalyst [texte imprimé] / Lie Lu, Auteur ; Hong Fan, Auteur ; Bo-Geng Li, Auteur . - 2010 . - pp. 8349–8355. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8349–8355 Mots-clés : Polypropylene  Ethylene−propylene  rubber  reactor  Propylene  homopolymerization  Metallocene  activation  Ethylene−propylene  copolymerization Résumé : Polypropylene/ethylene−propylene rubber (PP/EPR) reactor alloys were prepared with a metallocene/Ziegler−Natta hybrid catalyst system (rac-Et(Ind)2ZrCl2/TiCl4/MgCl2) using a process composed of three stages: propylene homopolymerization, metallocene activation, and ethylene−propylene copolymerization. A series of alloy samples were produced and characterized at various copolymerization conditions by varying the methylaluminoxane (MAO)/Zr ratio and monomer composition. It was shown that the metallocene/Ziegler−Natta hybrid system exhibited the features of both metallocene and Ziegler−Natta catalysts during copolymerization. The hybrid catalyst had better ability in incorporating α-olefin than the Ziegler−Natta catalyst owing to the action of metallocene active sites. DSC and IR analyses suggested that EPR in the alloys became random with increased MAO/Zr ratio. In addition, reducing the ethylene content in the feed decreased the activity and promoted the production of random copolymers. An operation window of reaction conditions was identified for the preparation of well-dispersed spherical PP/EPR reactor alloy particles containing up to about 40 wt % EPR. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900579h