Abstract: Components of bimetallic catalysts for the polymerization of olefins comprising a compound of a transition metal M selected from Ti, V, Zr and Hf containing at least one M-&pgr;bond, a compound of Ti or V not containing metal-&pgr; bonds and a support comprising a magnesium halide. The catalysts obtained from the components of the invention are particularly suitable for gas-phase polymerization processes.

Abstract: The present invention relates to mixed catalyst compositions of a Group 15 containing hafnium catalyst compound and a bulky ligand metallocene-type catalyst compound, a unsupported and supported catalyst systems thereof and to a process for polymerizing olefin(s) utilizing them.

Abstract: A multi-stage process for preparing ethylene (co)polymers having broad molecular weight distributions is disclosed, said process comprising: (A) a first polymerization stage in which, in the presence of a Ti or V catalyst, a first ethylene polymer is prepared; (B) a treatment stage in which the catalyst used in the first stage is deactivated and in which a bridged bis-2-indenyl zirconocene is supported on the ethylene polymer produced in stage (A), optionally in the presence of a suitable cocatalyst; and (C) a second polymerization stage in which ethylene is polymerized in the presence of the product obtained from stage (B). Furthermore, polyethylene obtainable by the above process is disclosed, having intrinsic viscosity ranging from 0.5 to 6 dl/g, Mw/Mn>8 and cold xylene solubility<1.2% wt.

Abstract: A catalyst composition comprises at least two different polymerization catalysts of which a) at least one is a polymerization catalyst based on an early transition metal component and b) at least one is a polymerization catalyst based on a late transition metal component.

Abstract: This invention relates to a process to polymerize olefins comprising reacting olefins with a combined catalyst system comprising a hydrogen generating olefin polymerization catalyst and from 10 ppm to 10 weight % of at least one hydrogen consuming olefin polymerization catalyst system, based upon the weight of the total catalyst present, not including any activators or supports.

Abstract: A process for the preparation of polymers containing double bonds by ruthenium carbene catalysis is carried out, where a ring-opening polymerization of monomers of the Formula (I) occurs 1

Abstract: A process, particularly a gas phase fluidised bed process, for the production of polymers avoids formation of sheets or chunks within the reactor, without the need to use antistatic agents, which can reduce the activity of the catalyst or alter the characteristics of the yielded product. According to the invention, a device generates a corona discharge in the polymerisation reactor during the polymerisation process; an AC voltage difference is applied between the elements which constitute the discharging pair of the device.

Abstract: The present invention relates to a process for the polymerization of monomers utilizing a bulky ligand hafnium transition metal metallocene-type catalyst compound, to the catalyst compound itself and to the catalyst compound in combination with an activator. The invention is also directed to an ethylene copolymer composition produced by using the bulky ligand hafnium metallocene-type catalysts of the invention, in particular a single reactor polymerization process. The hafnocene compound comprises at least one ligand substituted with at least one linear or iso alkyl substituent of at least 3 carbon atoms, and the catalyst system may comprise a mixture of two or more such hafnocenes.

Abstract: Process for the polymerization of olefins using a catalytic system comprising a solid precursor containing at least one neutral halogenated metallocene derived from a transition metal and at least one ionizing agent, and an organometallic compound derived from a metal chosen from groups IA, IIA, IIB, IIIA, and IVA of the Periodic Table.

Abstract: A catalyst system which combines a unbridged metallocene catalyst and a heterogeneous catalyst affects the molecular weight, the molecular weight distribution and the melt flow index of the resulting polymer. To obtain a polymer having high molecular weight and fractional melt flow index, the unbridged metallocene compound is preferably cyclopentadienyltitanium trichloride or bis(cyclopentadienyl)titanium dichloride and an alumoxane co-catalyst may or may not be present. To obtain a polymer having high molecular weight, broad molecular weight distribution and fractional melt flow index, the unbridged metallocene compound is preferably cyclopentadienyltitanium trichloride or bis(cyclopentadienyl)titanium dichloride and an alumoxane co-catalyst is present. A catalyst system which combines a unbridged metallocene catalyst and a bridged metallocene catalyst with the heterogeneous catalyst affects the xylene solubles in addition to the other polymer properties.

Abstract: A process for preparing a supported chromium-based catalyst for the production of high density polyethylene, by polymerising ethylene, or copolymerising ethylene and an alpha-olefinic comonomer comprising 3 to 10 carbon atoms, which comprises the steps of: a) providing an alumina-containing support; b) depositing a chromium compound on the support to form a chromium-based catalyst; c) dehydrating the chromium-based catalyst to remove physically adsorbed water by heating the catalyst at a temperature of at least 300° C. in an atmosphere of dry, inert gas; d) titanating the chromium-based catalyst at a temperature of at least 300° C.

Abstract: Ethylene polymer having a die swell ratio (RB) of at least 1.4, a resistance to crazing under stress (ESCR) of at least 55 h and a melt index (MI5) of at least 0.2 g/10 min. Processes for obtaining this ethylene polymer using different catalytic systems, the first based on titanium and zirconium used in a polymerization in two reactors; the second consisting of a mixture of a titanium catalyst and a titanium and zirconium catalyst, used in a polymerization in two reactors; the third based on chromium on a support comprising at least two constituents chosen from silica, alumina and aluminum phosphates, used in a polymerization in a single or in two reactors.

Abstract: The present invention relates to a supported chromium-based catalyst titanated under specific conditions and used for the homopolymerization or the copolymerization of ethylene. The polyethylene obtained with this catalyst has high shear resirance and environmental stress crack resistance, and can be used for manufacturing films with improved tear properties.

Abstract: The invention encompasses a mixed transition metal olefin polymerization catalyst system suitable for the polymerization of olefin monomers comprising one late transition metal catalyst system and at least one different catalyst system selected from the group consisting of late transition metal catalyst systems, transition metal metallocene catalyst systems or Ziegler-Natta catalyst systems. Preferred embodiments include at least one late transition metal catalyst system comprising a Group 9, 10, or 11 metal complex stabilized by a bidentate ligand structure and at least one transition metal metallocene catalyst system comprising a Group 4 metal complex stabilized by at least one ancillary cyclopentadienyl ligand. The polymerization process for olefin monomers comprises contacting one or more olefins with these catalyst systems under polymerization conditions.

Abstract: Polymers of ethylene are obtainable by polymerization of ethylene and, if desired, further comonomers in the presence of a catalyst system comprising as active constituents I) a Phillips catalyst, II) a solid which is different from I) and comprises a component which is derived from the metallocene complexes of the formula (A) in which the substituents and indices have the following meanings:  R1 to R10 are hydrogen, C1-C10-alkyl, 5-to 7-membered cycloalkyl which may in turn bear C1-C6-alkyl groups as substituents, C6-C15-aryl or aryalkyl, where two adjacent radicals may also together form a cyclic group having from 4 to 15 carbon atoms, or Si(R11)3, where R11 is C1-C10-alkyl, C6-C15-aryl or C3-C10-cycloalkyl, or the radicals R4 and R9 together form a group —[Y(R12R13)]m—, where Y is silicon, germanium, tin or carbon, and R12, R13 are hydrogen C1-C10-alky, C3-C10-cycloalyl or C6-C15-aryl, M is a metal of transition groups IV to VIII or a metal of the lanthanide

Abstract: A method for producing a low density copolymer of ethylene and 1-hexene having a density in the range of about 0.915 to about 0.930 grams/cc in a continuous loop reactor under slurry phase reactor conditions in the presence of a liquid diluent comprising (a) using a prepolymerized solid particulate metallocene catalyst system, (b) combining the catalyst system with a liquid diluent, and (c) agitating the mixture of (b) to form a liquid mixture containing catalyst system particles that are substantially uniform in size, (d) passing this liquid mixture into the loop reactor, (e) not adding any hydrogen, (f) employing the temperature in the range of about 170.degree. F. to about 180.degree. F., (g) employing ethylene in an amount equal to about 5 to about 6 weight % of the liquid diluent and the loop reactor, and (h) employing 1-hexene in an amount equal to about 1.5 to about 2.5 weight % of the liquid diluent in the loop reactor.

Abstract: Yttrium complexes of dibenzopyrolyl substituted cyclopentadienyl ligands are useful as ethylene polymerization catalysts to uniquely prepare low molecular weight ethylene polymers having a high degree of terminal vinyl unsaturation.

Abstract: Catalyst systems which are suitable for polymerizing ethylene and 1-alkenes comprise as active constituentsA) a chromium-containing component obtainable by reducing an oxidized Phillips catalyst with organic compounds selected from the group of linear C.sub.4 -C.sub.10 - or cyclic C.sub.3 -C.sub.10 -alkenes with at least one internal C.dbd.C double bond, of 1,3-butadiene, of C.sub.2 -C.sub.10 -alkynes and of C.sub.1 -C.sub.10 -aldehydes,with or withoutB) an organometallic compound of the first, second, third or fourth main group or of the second subgroup of the Periodic Table of the Elements.

Abstract: Mixtures of different polyolefins or branched polyolefins may be made by direct, preferably simultaneous, polymerization of one or more polymerizable olefins using two or more transition metal containing active polymerization catalyst systems, one of which contains preferably late transition metals complexed to selected ligands. The polyolefin products may have polymers that vary in molecular weight, molecular weight distribution, crystallinity, or other factors, and are useful as molding resins and for films.

Abstract: The present invention is directed to a process of atom (or group) transfer radical polymerization for the synthesis of novel homopolymer or a block or graft copolymer, optionally containing at least one polar group, with well defined molecular architecture and narrow polydispersity index, in the presence of an initiating system comprising (i) an initiator having a radically transferrable atom or group, (ii) a transition metal compound, and (iii) a ligand; the present invention is also directed to the synthesis of a macromolecule having at least two halogen groups which can be used as a macroinitiator component (i) to subsequently form a block or graft copolymer by an atom or group transfer radical polymerization process; the present invention is also directed to a process of atom or group transfer radical polymerization for the synthesis of a branched or hyperbranched polymer; in addition, the present invention is directed to a process of atom or group transfer radical polymerization for the synthesis of a ma

Abstract: Components and catalysts for the polymerization of olefins comprising the product obtained by contacting a compound of a transition metal M, containing at least one M-.pi. bond, with an olefinic prepolymer obtained by polymerization of one or more olefins with a coordination catalyst comprising a compound of Ti or V supported on a magnesium halide.

Abstract: It has been found that the use of at least one unsupported metallocene polymerization catalyst with at least one supported metallocene polymerization catalyst in the polymerization of olefins allows for better control of the polymerization, especially gas phase polymerization. Such a system takes advantage of the high activity of the unsupported catalyst and the stability of a supported catalyst. Additionally, the relative timing of the addition of the supported and unsupported catalysts to a reaction system can be used to control a continuous polymerization reaction by stabilizing the reactor bed with the supported catalyst prior to addition of the unsupported catalyst.

Abstract: Organopolysiloxane particles useful as catalysts, are cross-linked, comprise a single molecule, have chemically bound metallic compounds and an average diameter of from 5 to 200 nm and are soluble in at least one solvent chosen from dichloromethane, pentane, acetone, ethanol and water to at least 1% by weight. At least 80% of the particles have a diameter which deviates a maximum of 30% from the average diameter.

Abstract: A process is provided for preparing polymer compositions which are multimodal in nature. The process involves contacting, under polymerization conditions, a selected addition polymerizable monomer with a metallocene catalyst having two or more distinct and chemically different active sites, and a catalyst activator.

Abstract: The present invention relates to a prepolymer for the polymerization of olefins, the said prepolymer achieving a combination of a number of solid catalytic components for the polymerization of olefins. The combination of catalytic components makes it possible to combine two properties within the same polymer, one of the properties being contributed by one of the catalytic components and the other property being contributed by the other catalytic component.

Abstract: Support for catalysts, containing at least two constituents chosen from silica, alumina and aluminium phosphate, having a specific surface of 100 to 800 m.sup.2 /g, a crystallization temperature greater than or equal to 700.degree. C. and a pore volume of 1.5 to 4 cm.sup.3 /g, the specific surface (SS) and the pore volume (PV) corresponding to the relationship:SS<(PV.times.564-358).Process for the manufacture of such a support, according to which an alcohol, water, a silicon alkoxide and an acid are mixed under conditions such that gelling or precipitation of silica is prevented, an acidic solution of an aluminium compound and/or a solution of a source of phosphate ions are added thereto, a gelling agent is added thereto, a gel is recovered which is washed with water and then by means of an organic liquid, the gel is then dried until a powder is obtained, and the powder is calcined. Polymerization of olefins in the presence of a catalyst containing chromium on a support as described above.

Abstract: A process for preparing polynuclear metallocenes by reacting a metallocene in which one of the cyclopentadienyl-containing radicals has a substituent having olefinic or acetylenic unsaturation with a second metallocene having a metal which comes from groups IVb to VIb of the periodic table and a metal-hydride bond. The use of the resulting metallocenes in the polymerization of olefins is disclosed, including techniques for using such metallocenes to produce solid prepolymerized metallocene-containing catalyst systems suitable for use in the polymerization of olefins.

Abstract: Process for the photocatalytic polymerization of a cyclic olefin or at least two different cyclic olefins in the presence of a metal compound as catalyst, which comprises carrying out a photochemical ring-opening metathesis polymerization in the presence of a catalytic amount of at least one heat-stable niobium(V) or tantalum(V) compound which contains at least two methyl groups or two monosubstituted methyl groups bound to the metal, the substituent containing no hydrogen atom in the .alpha.-position.The process can also be carried out by first performing the irradiation and completing the polymerization by heating. The process is suitable, for example, for the preparation of thermoplastic molding materials, coatings and relief images.

Abstract: Novel chromium-containing compounds are prepared by forming a mixture of a chromium salt, a metal amide, and an ether. These novel chromium-containing, or chromium pyrrolide, compounds, with a metal alkyl and an unsaturated hydrocarbon, can be used as a cocatalyst system in the presence of an olefin polymerization catalyst system to produce a comonomer in-situ. The resultant polymer, although produced from predominately one monomer, has characteristics of a copolymer.

Abstract: Ethylene copolymers are disclosed herein which are each derived from ethylene and an olefin of C.sub.3 to C.sub.20 and in which any quaternary carbon atom is not present in a polymeric main chain; the activation energy (Ea) of melt flow is in the range of 8 to 20 kcal/mol; and (1) a ratio between a Huggins coefficient (k.sup.1) of the copolymer and a Huggins coefficient (k.sup.2) of a straight-chain ethylene polymer having the same intrinsic viscosity meets the equation 1.12<k.sup.1 /k.sup.2 .ltoreq.5, or (2) a molar ratio ?CH.sub.3 /CH.sub.2 ! of a methyl group to a methylene group in a molecular chain is in the range of 0.005 to 0.1, and the equation Tm.gtoreq.131-1,340 ?CH.sub.3 /CH.sub.2 ! is met, or (3) Mw and a die swell ratio (DR) meet the equation DR>0.5+0.125.times.log Mw.

Abstract: The preparation and use of organometallic complexes of Group III metals having the formula:Me(Ar)(AlX.sub.3 R).sub.3 (I)wherein Me, Ar, X and R are as defined herein, to stereospecifically polymerize unsaturated monomers is provided.

Abstract: A process for effectively producing a cyclic olefin polymer and a cyclic olefin/alpha-olefin copolymer without opening the cyclic olefin, is disclosed. Further, a novel cyclic olefin/alpha-olefin copolymer prepared by the above-mentioned process, compositions and molded articles comprising the novel copolymer, are also disclosed. In the process for producing a cylcic olefin based polymer according to the present invention, homopolymerization of a cyclic olefin or copolymerization of a cyclic olefin and an alpha-olefin is effected in the presence of a catalyst comprising, as main ingredients, the following Compounds (A) and (B), and optionally Compound (C):(A) a transition metal compound;(B) a compound capable of forming an ionic complex when reacted with a transition metal compound; and(C) an organoaluminum compound.

Abstract: There are disclosed a catalyst for producing an aromatic vinyl compound-based polymer composition which catalyst comprises (A) at least two different transition metal compounds each having one .pi.-ligand and (B) an ionic compound comprising a noncoordinate anion and a cation and/or an aluminoxane, and (C) a Lewis acid to be used as the case may be; and a process for producing an aromatic vinyl compound-based polymer composition having a high degree of syndiotactic configuration in its aromatic vinyl chains which process comprises polymerizing an (a) aromatic vinyl compound and (b) an olefinic compound and/or a diolefinic compound in the presence of the above catalyst.

Abstract: Olefin polymerization catalysts the procatalyst component of which comprises a transition-metal compound on a magnesium chloride support material are known to all. Now the procatalyst component has been improved by incorporating a manganese (II) halide into it at a rate of at minimum approx. 0.1% and at maximum approx. 50% of the total molar amount of magnesium chloride and manganese (II) halide. The new polymerization catalyst has, among other things, the excellent special property that it yields a polyolefin with a broad molecular weight distribution.

Abstract: Cycloolefin/alpha-olefin copolymers in a molar ratio from 5/95 to 95/5, optionally including long linear alpha-olefin, branched alpha-olefins and/or polyenes as additional comonomers, are prepared using a cyclopentadienyl metallocene catalyst system based on a transition metal compound from Group 4 of the Periodic Table of Elements. The copolymers have a high molecular weight, a narrow molecular weight distribution and a substantially uniform, random comonomer distribution.

Abstract: Catalytic solid for the (co)polymerisation of at least one olefin, comprising a coprecipitate of magnesium and of at least one transition metal, obtained by means of a process comprising the preparation of a mixture of a magnesium compound, such as the chloride or a magnesium alcoholate, and of a compound denoted by one of the formulae MY.sub.x (O--R').sub.t-x and M'O.sub.y (O--R").sub.s-2y and the treatment of the resulting mixture with a complex of formula M"(A)Al.sub.2 (X',X").sub.8 where X' and X" denote halogens, M and M' transition metals of groups IVB and VB, M" a transition metal of group IVB, A an aromatic hydrocarbon, Y a halogen or a group (O--R'"), and R', R" and R'" an alkyl, aryl or cycloalkyl group.

Abstract: A process for effectively producing a cyclic olefin polymer and a cyclic olefin/alpha-olefin copolymer without opening the cyclic olefin, is disclosed. Further, a novel cyclic olefin/alpha-olefin copolymer prepared by the above-mentioned process, compositions and molded articles comprising the novel copolymer, are also disclosed. In the process for producing a cylcic olefin based polymer according to the present invention, homopolymerization of a cyclic olefin or copolymerization of a cyclic olefin and an alpha-olefin is effected in the presence of a catalyst comprising, as main ingredients, the following Compounds (A) and (B), and optionally Compound (C):(A) a transition metal compound;(B) a compound capable of forming an ionic complex when reacted with a transition metal compound; and(C) an organoaluminum compound.

Abstract: Disclosed is a novel transition metal compound represented by the following formula: ##STR1## wherein M is a transition metal, X is halogen or the like, R.sup.1 is a hydrocarbon group or the like, R.sup.2 is an aryl group substituted with a halogenated hydrocarbon group, and Y is a divalent silicon-containing group or the like.Also disclosed are an olefin polymerization catalyst component comprising the transition metal compound, an olefin polymerization catalyst comprising the olefin polymerization catalyst component, and a process for olefin polymerization using the olefin polymerization catalyst.An olefin polymerization catalyst component having high polymerization activity can be formed from the transition metal compound. By the use of the olefin polymerization catalyst or the process for olefin polymerization, polyolefins having a high melting point and a high molecular weight can be prepared with high polymerization activity.

Abstract: A catalyst system comprising a bridged fluorenyl-containing metallocene, an unbridged metallocene, and a suitable cocatalyst and the use of such catalyst systems to produce olefin polymers. Also novel olefin polymers produced by those processes.

Abstract: This invention is generally directed toward a supported catalyst system useful for polymerizing olefins. The method for supporting the catalyst of the invention provides for a supported mixed metallocene/non-metallocene catalyst useful in a process for polymerizing olefins.

Abstract: There are disclosed a catalyst for producing an aromatic vinyl compound polymer which catalyst comprises a contact product between an (A) trivalent titanium compound and a (B) compound represented by the general formula (II) or (III)R.sup.1.sub.k M.sup.1 L.sup.2.sub.m (II)R.sup.1.sub.k M.sup.1 X.sup.2.sub.l L.sup.2.sub.m (III)a (C) an ionic compound comprising a noncoordinate anion and a cation, an aluminoxane or an organoboron compound; and optionally a (D) Lewis acid, and a process for producing an aromatic vinyl compound polymer having a high degree of syndiotactic configuration which process comprises polymerizing (a) an aromatic vinyl compound or (b) an aromatic vinyl compound together with an olefin or a diolefin in the presence of the above catalyst.

Abstract: Chromium catalyst compositions are provided. These chromium catalyst compositions comprise at least two chromium catalyst systems that have a certain amount of chromium and a support that comprises silica and titania. the supports have certain pore volumes and surface areas. These catalyst compositions are useful for homopolymerizing ethylene or copolymerizing ethylene with a comonomer. The resins produced are useful in film applications.

Abstract: Chromium catalyst compositions are provided. Theses chromium catalyst compositions can be used to polymerized olefins. The resulting polymerization product can have improved properties.

Abstract: A polymerization process for olefins, diolefins and/or acetylenically unsaturated monomers is described. The monomers are contacted with an ionic catalyst which comprises a cyclopentadienyl derivative of Group IV-B metals as cation and a compatible non-coordinating anion containing a plurality of boron atoms. Borate, carborate, borane, carborane, metallaborane and metallacarborane compounds exemplify anion sources and dihydrocarbyl-substituted bis(cyclopentadienyl) zirconium compounds exemplify the Group IV-B metal cation sources.

Abstract: A support containing methylalumoxane and derivatives thereof is described which is formed by an incipient impregnation technique. The most preferred support is silica. Incipient impregnation in accordance with the invention provides a supported alumoxane, methylalumoxane, which substantially eliminates the problem of fluid bed reactor fouling when methylalumoxane is introduced into the reactor during its operation. The process comprises providing methylaluminoxane in particulate form for use as a catalytic component in the fluidized bed gas phase polymerization process.In accordance with the invention, the process comprises providing methylalumoxane activated metallocene compound in particulate form as catalysts in fluid bed gas phase.

Abstract: Ethylene is homopolymerized in the presence of a catalyst consisting essentially of a Group 3 metal complex, preferably a scandium complex, having a bridged ligand structure. Optionally polymer blends are prepared by combining the process with another polymerization process, either in series or in parallel.

Abstract: Disclosed is a method of making polyethylene wherein ethylene, a catalyst, a cocatalyst and a solvent are added to a reactor. A first mixture is formed of the ethylene and either the catalyst or the cocatalyst and a second mixture is separately formed of the solvent and the other of the catalyst or cocatalyst. These two mixtures are then combined in a reactor to produce the polyethylene.

Abstract: A novel transition metal compound represented by the formula ##STR1## (wherein each of A.sup.1, A.sup.2, A.sup.3 and A.sup.4 is a cyclopentadienyl group, an indenyl group, a fluorenyl group or their derivative; A.sup.5 is a hydrocarbondiylidene group having 4 to 30 carbon atoms; a pair of A.sup.1 and A.sup.2 as well as a pair of A.sup.3 and A.sup.4 is respectively bonded to the identical carbon atom in A.sup.5 to form a crosslinking structure; each of R.sup.1 and R.sup.2 is a halogen atom, a hydrogen atom, an alkyl group or a silicon-containing alkyl group having 1 to 10 carbon atoms, an aryl group, an alkylaryl group, an arylalkyl group or a halogenated aryl group having 6 to 20 carbon atoms; R.sup.1 and R.sup.2 may be identical or different; each of M.sup.1 and M.sup.2 is titanium, zirconium or hafnium; and M.sup.1 and M.sup.2 may be mutually identical or different), and a method for polymerizing an olefin in the presence of this compound and a co-catalyst.

Abstract: An olefin metathesis catalyst system and process for the metathesis polymerization of cyclic olefins, such as dicyclopentadiene, are disclosed. The catalyst system comprises the reaction product of:(a) an imido transition metal halide complex of formula: ##STR1## wherein Ar is C.sub.6-20 aryl, preferably phenyl; M is a transition metal selected from the second and third rows of Groups 5, 6, 7 and 8 of the Periodic Table (IUPAC 1989 convention) and including for example niobium, tantalum, molybdenum, tungsten, rhenium, ruthenium or osmium, preferably tungsten or molybdenum; R is independently halide, C.sub.1-20 alkyl, C.sub.1-12 alkoxy, C.sub.1-12 haloalkyl, C.sub.6-20 aryl, C.sub.6-20 aryloxy, cyano or combinations thereof; L is independently a complexing ligand selected from carbonyl, C.sub.1-12 alkoxy, C.sub.1-12 haloalkoxy, C.sub.1-12 alkyl ethers, including mono-, di- and higher ethers, C.sub.12 alkylnitriles, C.sub.5-20 pyridines, C.sub.

Abstract: An improved catalyst system and process of producing polyolefins having a controllable broadened molecular weight distribution utilizing transition metal metallocene catalyst systems, wherein at least one of the metallocenes has at least one cyclopentadienyl ring being substituted by at least one optionally substituent having a 2.degree. or 3.degree. carbon atom with which it is covalently bonded to the cyclopentadienyl ring. The method for forming the catalyst system of this present invention can be either by a physical or a chemical mixing process.