Kinetic modeling and simulation of metallocene catalyzed olefin polymerization

Abstract

Metallocene catalyst system refers to the combination of biscyclopentadienylmetal newlinecomplexes of Group 4 IVB or cyclopentadienylsubstituted derivatives thereof and a newlinecocatalyst typically methylalumoxane MAO Metallocene catalysts have in general newlinedemonstrated high productivity narrow molecular weight distribution MWD greater newlineefficiency in using comonomer to reduce the density capability of producing polymer newlinewith varying molecular weights and controlled stereoregularity newlineMetallocene based catalyst technology is expected to revolutionize the polyolefin newlineindustry immensely particularly in polyethylene and polypropylene markets Metallocene newlinepolyolefins are projected to penetrate a broad array of polymer markets First with the newlinehigher priced specialty markets followed by the high volume and commodity markets newlineNew markets are also expected to be created with the development of new classes of newlinepolymer those are not possible with conventional ZieglerNatta technologies newlineIn the present work the mechanistic aspects of ZieglerNatta and metallocene newlinecatalyst systems have been studied in detail and used in building up mathematical models newlinefor and#945;olefin polymerization using metallocene catalysts Based on the interpretations of newlinemechanisms for metallocenecatalyzed polymerization an ecumenical reaction set for newlineethylene and propylene polymerization that includes reactions corresponding to all types newlineof metallocenes is proposed Thereafter mathematical models for ethylene and and#945;olefin newlinepolymerization in a batchsemibatchconstantstirredtank reactor are built up The newlinemodels developed are capable of predicting polymerization kinetics and polymer newlineproperties viz numberaverage weightaverage molecular weights and polydispersity newlineindex in general In addition mole fraction of dead polymer chains with terminal double newlinebond and density of longchain branches shortchain branches may be determined with newlineethylene polymerization model Fraction of vinylterminated chains butenylterminated newlinechains isobutylterminated chains and vinylideneterminated chains relative to the tot.