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1.
Esa Kokko Pirjo Pietikinen Jari Koivunen Jukka V. Seppl 《Journal of polymer science. Part A, Polymer chemistry》2001,39(21):3805-3817
Ethene was copolymerized (1) with 1,5‐hexadiene with rac‐ethylenebis(indenyl)zirconium dichloride/methylaluminoxane (MAO) used as a catalyst and (2) with 1,7‐octadiene with bis(n‐butylcyclopentadienyl)zirconium dichloride/MAO and rac‐ethylenebis(indenyl)hafnium dichloride (Et[Ind]2HfCl2)/MAO used as catalysts at 80 °C in toluene. The copolymer microstructure and the influence of diene incorporation on the rheological properties were examined. Ethene and 1,5‐hexadiene formed a copolymer in which a major fraction of the 1,5‐hexadiene was incorporated into rings and a small fraction formed 1‐butenyl branches. The copolymerization of ethene with 1,7‐octadiene resulted in a higher selectivity toward branch formation. Some of the branches formed long‐chain‐branching (LCB) structures. The ring formation selectivity increased with decreasing ethene concentration in the polymerization reactor. Melt rheological properties of the diene copolymers resembled those of metallocene‐catalyzed LCB homopolyethenes and depended on the vinyl content, the catalyst, and the polymerization conditions. At high diene contents, all three catalysts produced crosslinked polyethene. This was especially pronounced with Et[Ind]2HfCl2, where only 0.2 mol % 1,7‐octadiene in the copolymer was required to achieve significantly modified rheological properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3805–3817, 2001 相似文献
2.
Robert T. Mathers Krishnan Damodaran 《Journal of polymer science. Part A, Polymer chemistry》2007,45(15):3150-3165
Monoterpenes were used as renewable chain transfer agents and polymerization solvents for metallocene/methylaluminoxane (MAO) catalysis. The polymerization of 1‐hexene, ethylene, and propylene in d‐limonene, hydrogenated d‐limonene and α‐pinene is reported. As detected by 1H NMR analysis of the alkene region, chain transfer to d‐limonene yielded a higher percentage of trisubstituted alkenes. Size exclusion chromatography detected a decrease in molecular weight values resulting from chain transfer to d‐limonene. The [mmmm] pentads for isotactic polypropylene were characterized by 13C NMR and FTIR spectroscopy. Propylene polymerizations with the Et(Ind)2ZrCl2/MAO and Me2Si(Ind)2ZrCl2/MAO catalyst systems in d‐limonene gave [mmmm] pentad values as high as 0.97. For the Et(Ind)2ZrCl2/MAO catalyst system at 0 °C, the mol fraction of [mmmm] pentads increased from 0.86 to 0.94 upon switching the solvent from toluene to d‐limonene. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3150–3165, 2007 相似文献
3.
Erkki Aitola Kimmo Hakala Hedvig Byman‐Fagerholm Markku Leskelä Timo Repo 《Journal of polymer science. Part A, Polymer chemistry》2008,46(1):373-382
The influence of ligand structure on copolymerization properties of metallocene catalysts was elucidated with three C1‐symmetric methylalumoxane (MAO) activated zirconocene dichlorides, ethylene(1‐(7, 9)‐diphenylcyclopenta‐[a]‐acenaphthadienyl‐2‐phenyl‐2‐cyclopentadienyl)ZrCl2 ( 1 ), ethylene(1‐(7, 9)‐diphenylcyclopenta‐[a]‐acenaphthadienyl‐2‐phenyl‐2‐fluorenyl)ZrCl2 ( 2 ), and ethylene(1‐(9)‐fluorenyl‐(R)1‐phenyl‐2‐(1‐indenyl)ZrCl2 ( 3 ). Polyethenes produced with 1 /MAO had considerable, ca. 10% amount of trans‐vinylene end groups, resulting from the chain end isomerization prior to the chain termination. When ethene was copolymerized with 1‐hexene or 1‐hexadecene using 1 /MAO, molar mass of the copolymers varied from high to moderate (531–116 kg/mol) depending on the comonomer feed. At 50% comonomer feed, ethene/1‐olefin copolymers with high hexene or hexadecene content (around 10%) were achievable. In the series of catalysts, polyethenes with highest molar mass, up to 985 kg/mol, were obtained with sterically most crowded 2 /MAO, but the catalyst was only moderately active to copolymerize higher olefins. Catalyst 3 /MAO produced polyethenes with extremely small amounts of trans‐vinylene end groups and relatively low molar mass 1‐hexene copolymers (from 157 to 38 kg/mol) with similar comonomer content as 1 . These results indicate that the catalyst structure, which favors chain end isomerization, is also capable to produce high molar mass 1‐olefin copolymers with high comonomer content. In addition, an exceptionally strong synergetic effect of the comonomer on the polymerization activity was observed with catalyst 3 /MAO. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 373–382, 2008 相似文献
4.
Naoya Kishi Cheol‐Hee Ahn Jizhu Jin Toshiya Uozumi Tsuneji Sano Kazuo Soga 《Macromolecular rapid communications》2000,21(11):775-778
Supported type cocatalysts using triphenylcarbenium perchlorate (Ph3CClO4) were prepared by impregnation on inorganic carrier, magnesium chloride (MgCl2) and applied to ethylene polymerizations with rac‐Et[Ind]2ZrCl2. Homogeneous polymerizations with Ph3CClO4 were also carried out for comparison. The activity of homogeneous polymerization was much lower than that obtained with methylaluminoxane (MAO). On the other hand, rac‐Et[Ind]2ZrCl2 activated by the supported type Ph3CClO4/MgCl2 system displayed high activity comparable to that obtained with MAO. From the results of fractionation and polymerization of the rac‐Et[Ind]2ZrCl2‐Ph3CClO4/MgCl2 catalyst system, it was found that the increased activity mainly came from the active species in the supernatant part. UV‐vis spectroscopic measurements combined with ICP analysis indicate that the active species in the supernatant fraction are composed of a stoichiometric amount of perchlorate and metallocene catalyst. 相似文献
5.
Eleonora Polo Simona Losio Maria Carmela Sacchi Maurizio Galimberti 《Journal of polymer science. Part A, Polymer chemistry》2013,51(6):1436-1447
New ω‐alkenyl‐substituted ansa‐bridged bisindenyl zirconium complexes are prepared and tested as self‐immobilized catalysts for ethene polymerization. But, even at very high concentration of the tethered complexes and low pressure of ethene, there is no evidence of their insertion into the polyethene chain. A “cross polymerization” test, performed by copolymerizing the tethered complexes with ethene using rac‐Me2Si(2‐MeBenzInd)2ZrCl2 ( MBI ), does not lead to their incorporation into the polyethene chain. However, the corresponding ligand proves to be a suitable comonomer for ethene, and, through copolymerization promoted by MBI, innovative poly(ethene‐co‐2,2′‐bis[(1H‐inden‐3′‐yl)‐hex‐5‐ene) copolymers are prepared and characterized by 13C NMR. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
6.
Tsuneji Sano Hitoshi Hagimoto Jizhu Jin Yasunori Oumi Toshiya Uozumi Kazuo Soga 《Macromolecular rapid communications》2000,21(17):1191-1195
Inorganic siliceous porous materials such as MFI type zeolite, mesoporous silica MCM‐41 and silica gel with different average pore diameters were applied to the adsorptive separation of methylaluminoxane (MAO) used as a cocatalyst in α‐olefin polymerizations. The separated MAOs combined with rac‐ethylene‐(bisindenyl)zirconium dichloride (rac‐Et(Ind)2ZrCl2) were introduced to propylene polymerization, and their influences on the polymerization activity and stereoregularity of the resulting polymers were investigated. The polymerization activity and isotactic [mmmm] pentad of the produced propylene were markedly dependent upon the pore size of the porous material used for adsorptive separation. From the results obtained from solvent extraction of the produced polymers, it was suggested that there are at least two kinds of active species with different stereospecificity in the rac‐Et(Ind)2ZrCl2/MAO catalyst system. 相似文献
7.
Junwei Zhang Bo‐Geng Li Hong Fan Shiping Zhu 《Journal of polymer science. Part A, Polymer chemistry》2007,45(16):3562-3569
In this work, ethylene‐1‐hexene copolymers were synthesized with a tandem catalysis system that consisted of a new trimerization catalyst bis(2‐dodecylsulfanyl‐ethyl) amine‐CrCl3/MAO ( 1 /MAO) and copolymerization catalyst Et(Ind)2ZrCl2/MAO ( 2 /MAO) at atmosphere pressure. Catalyst 1 trimerized ethylene with high activity and excellent selectivity in the presence of a relatively low amount of MAO. Catalyst 2 incorporated the 1‐hexene content and produced ethylene‐1‐hexene copolymer from an ethylene‐only stock in the same reactor. Adjusting the Cr/Zr ratio and reaction temperature yielded various branching densities and thus melting temperatures. However, broad DSC curves were observed when low temperatures and/or high Cr/Zr ratios were employed due to an accumulation of 1‐hexene component and composition drifting during the copolymerization. It was found that a short pretrimerization period resulted in more homogeneous materials that gave unimodal DSC curves. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3562–3569, 2007 相似文献
8.
Fernando Silveira Denise Santos de Sá Zênis Novais da Rocha João Henrique Zimnoch dos Santos 《大分子反应工程》2008,2(3):253-264
A series of metallocenes, namely [Cp2ZrCl2], [(MeCp)2ZrCl2], [(nBuCp)2ZrCl2], [(iBuCp)2ZrCl2], [(tBuCp)2ZrCl2], [Cp2TiCl2], [Et(Ind)2ZrCl2], [Et(IndH4)2ZrCl2] and [MeSi2(Ind)2ZrCl2)], were combined in a 1:1 molar ratio within a reactor for ethylene polymerization, with MAO as the cocatalyst. The catalysts were characterized by cyclic and differential pulse voltammetry. The combined systems that showed the highest and lowest activities were combined in 1:3 and 3:1 molar ratios. The catalyst activity in the ethylene polymerization reaction is discussed in terms of the estimated consumption rate, decomposition rate constant and half‐life of the metallocene species formed with MAO in an ethylene atmosphere.
9.
Christel Lehtinen Paul Starck Barbro Lfgren 《Journal of polymer science. Part A, Polymer chemistry》1997,35(2):307-318
The suitability of the (n-butCp)2ZrCl2/methylaluminoxane (MAO) catalyst system for the copolymerization of ethene with propene, hexene, and hexadecene was studied and Ind2ZrCl2/MAO was tested as a catalyst for ethene/propene and ethene/hexene copolymerizations. The synergistic effect of longer α-olefin on propene incorporation in ethene/propene/hexene and ethene/propene/hexadecene terpolymerizations was investigated with Et(Ind)2ZrCl2MAO and (n-butCp)2ZrCl2/MAO catalyst systems. The molar masses, molar mass distributions, melting points, and densities of the products were measured. The incorporation of comonomer in the chain was further studied by segregation fractionation techniques (SFT), by differential scanning calorimetry (DSC), studying the β relaxations by dynamic mechanical analysis (DMA) and by studying the microstructure of some copolymers by 13C-NMR. In this study (n-butCp)2ZrCl2 and Ind2ZrCl2 exhibited equal response in copolymerization of ethene and propene and both catalysts were more active towards propene than longer α-olefins. A nearly identical incorporation of propene in the chain was found for the two catalysts when a higher propene feed was used. A lower hexene feed gave a more homogeneous comonomer distribution curve than a higher hexene feed and also showed the presence of branching. In terpolymerizations catalyzed with (n-butCp)2ZrCl2, the hexadecene concentrations of the ethene/propene/hexadecene terpolymers were always very low, and only traces of hexene were detected in ethene/propene/hexene terpolymers. With hexene no clear synergistic effect on the propene incorporation in the terpolymer was detected and with hexadecene the effect of the longer α-olefin was even slightly negative. With an Et(Ind)2ZrCl2/MAO catalyst system both hexene and hexadecene were incorporated in the chain in the terpolymerizations. © 1997 John Wiley & Sons, Inc. 相似文献
10.
Guoqiang Fan Jin‐Yong Dong Zhigang Wang T. C. Chung 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):539-548
This paper discusses a new process of preparing borane‐terminated isotactic polypropylenes (i‐PPs) via in situ chain transfer reaction, which avoids the use of B‐H‐containing chain transfer agent and thus can be carried out with Al‐activated metallocene catalyst under mild reaction conditions. The chemistry centers on a consecutive chain transfer reaction, first to a trialkylborane‐containing styrene derivative, 4‐[B‐(n‐butylene)‐9‐BBN]styrene (B‐styrene), then to hydrogen in the isoselective polymerization of propylene catalyzed by rac‐Me2Si(2‐Me‐4‐Ph‐Ind)2ZrCl2/MAO. The borane‐terminated i‐PP thus obtained keeps the desired properties of a polymeric alkyl‐9‐BBN reagent and was used to initiate radical polymerization of methyl methacrylate (MMA) to prepare i‐PP‐b‐PMMA diblock copolymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 539–548, 2006 相似文献
11.
Johannes Carolus Jansen Raniero Mendichi Paolo Locatelli Incoronata Tritto 《Macromolecular rapid communications》2001,22(17):1394-1398
The kinetics of the ethylene‐norbornene copolymerization, catalyzed by rac‐Et(Ind)2ZrCl2/MAO, 90%rac/10%meso‐Et(4,7‐Me2Ind)2ZrCl2/MAO and rac‐H2C(3‐tert‐BuInd)2ZrCl2/MAO was followed by sampling from the reaction mixture at fixed time intervals. Catalyst activity, copolymer composition and molar mass were studied as a function of time. The polymers showed an unusually low polydispersity and a significant increase in their molar mass with time, suggesting a quasi‐living polymerization. 相似文献
12.
Random propene/4‐methyl‐1‐pentene copolymers synthesized with C2 symmetric highly isospecific metallocenes 下载免费PDF全文
Maria Carmela Sacchi Simona Losio Luigi Fantauzzi Paola Stagnaro Roberto Utzeri Maurizio Galimberti 《Journal of polymer science. Part A, Polymer chemistry》2015,53(22):2575-2585
Propene (P)/4‐methyl‐1‐pentene (Y) copolymers in a wide range of composition were prepared with isospecific single center catalysts, rac‐Et(IndH4)2ZrCl2 ( EBTHI ), rac‐Me2Si(2‐Me‐BenzInd)2ZrCl2 ( MBI ), and rac‐CH2(3‐tBuInd)2ZrCl2 ( TBI ). 13C NMR analysis of copolymers and statistical elaboration of microstructural data at triad level were performed. Unprecedented and surprising results are here reported. Random P/Y copolymers were prepared with the most isospecific catalyst, TBI , that is known to prepare ethene/propene and ethene/4‐methyl‐1‐pentene copolymers with long homosequences of both comonomers, whereas longer homosequences of both comonomers were observed in copolymers from the less enantioselective metallocenes EBTHI and MBI . These findings, which are against what is acknowledged in the field, can pave the way for the preparation on a large scale of random propene‐based copolymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2575–2585 相似文献
13.
I. N. Meshkova E. V. Kiseleva V. G. Krasheninnikov A. N. Shchegolikhin 《Polymer Science Series B》2017,59(1):62-68
Polar groups are introduced into polyolefin chains via the postpolymerization polymer-analogous transformations using the ozonolysis of side ethylidene groups of ethylene (propylene) copolymers with the cyclic comonomer 5-ethylidene-2-norbornene. The copolymers are synthesized using ansa-zirconocene catalysts Me2Si[Ind]2ZrCl2/MAO, Et[Ind]2ZrCl2/MAO and Et[IndH4]2ZrCl2/MAO, which provide insersion of the cyclic monomer into the polymer chain without ring opening. The study of number-average molecular mass and compositions of homo- and copolymers of ethylene and propylene with 5-ethylidene-2-norbornene confirms a high selectivity of the ozonolysis of unsaturated double bonds of polyolefins. The formation of polar groups in the ozonized ethylene and propylene copolymers with 5-ethylidene-2-norbornene is proved by IR and Raman spectroscopy. The thermophysical characteristics of the initial and ozonized copolymers are compared. 相似文献
14.
The incorporation of 5‐vinyl‐2‐norbornene (VNB) into ethylene‐norbornene copolymer was investigated with catalysts [Ph2C(Fluo)(Cp)]ZrCl2 ( 1 ), rac‐[Et(Ind)2]ZrCl2 ( 2 ), and [Me2Si(Me4Cp)tBuN]TiCl2 ( 3 ) in the presence of MAO by terpolymerizing different amounts of 5‐vinyl‐2‐norbornene with constant amounts of ethylene and norbornene at 60°C. The highest cycloolefin incorporations and highest activity in terpolymerizations were achieved with 1 . The distribution of the monomers in the terpolymer chain was determined by NMR spectroscopy. As confirmed by XRD and DSC analysis, catalysts 1 and 3 produced amorphous terpolymer, whereas 2 yielded terpolymer with crystalline fragments of long ethylene sequences. When compared with poly‐(ethylene‐co‐norbornene), VNB increased both the glass transition temperatures and molar masses of terpolymers produced with the constrained geometry catalyst whereas decreased those for the metallocenes. 相似文献
15.
Jung Dae Kim Joo B. P. Soares Garry L. Rempel 《Journal of polymer science. Part A, Polymer chemistry》1999,37(3):331-339
Tailoring of the molecular weight distribution (MWD) in ethylene polymerization was attempted by selectively combining different types of metallocene catalysts onto a single support. The catalyst produced by supporting Et[Ind]2ZrCl2 and Cp2HfCl2 onto a single MAO pretreated silica support was able to produce polymers with unimodal or bimodal MWD's. This approach permits the synthesis of polyethylene with different MWD's using the same catalyst as a function of the polymerization conditions. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 331–339, 1999 相似文献
16.
Marco Antnio da Silva Griselda Barrera Galland 《Journal of polymer science. Part A, Polymer chemistry》2008,46(3):947-957
Ethylene (E), propylene (P), and 1‐pentene (A) terpolymers differing in monomer composition ratio were produced, using the metallocenes rac‐ethylene bis(indenyl) zirconium dichloride/methylaluminoxane (rac‐Et(Ind)2ZrCl2/MAO), isopropyl bis(cyclopentadienyl)fluorenyl zirconium dichloride/methylaluminoxane (Me2C(Cp)(Flu)ZrCl2/MAO, and bis(cyclopentadienyl)zirconium dichloride, supported on silica impregnated with MAO (Cp2ZrCl2/MAO/SiO2/MAO) as catalytic systems. The catalytic activities at 25 °C and normal pressure were compared. The best result was obtained with the first catalyst. A detailed study of 13C NMR chemical shifts, triad sequences distributions, monomer‐average sequence lengths, and reactivity ratios for the terpolymers is presented. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 947–957, 2008 相似文献
17.
Ilpo Mustonen Terttu Hukka Tuula Pakkanen 《Macromolecular rapid communications》2000,21(18):1286-1290
Synthesis and characterization of a novel carbazole‐based monomer, 9‐(bicyclo[2.2.1]hept‐5‐en‐2‐ylmethyl)‐9H‐carbazole (BHMCZ) and its copolymerization with ethylene by using two metallocene/MAO catalyst systems are presented. The monomer was characterized by means of NMR spectroscopy, MS and elementary analysis. Copolymerization studies were conducted using [Ph2C(Ind)(Cp)ZrCl2] and [Ph2C(Flu)(Cp)ZrCl2] catalysts. The [Ph2C(Ind)(Cp)ZrCl2] catalyst gave a copolymer containing as much as 4.6 mol‐% of BHMCZ. Polymers were characterized using NMR spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). 相似文献
18.
J. O. Liimatta B. Lfgren M. Miettinen M. Ahlgren M. Haukka T. T. Pakkanen 《Journal of polymer science. Part A, Polymer chemistry》2001,39(9):1426-1434
Dynamic mechanical thermoanalysis showed that polyethene, prepared under suitable polymerization conditions with the Brookhart‐type catalyst dibromo‐N,N′‐1,2‐acenaphthylenediylidenebis[2,6‐bis(1‐methylethyl)benzeneamine]Ni(II)/methylaluminoxane (MAO), behaved like an elastomer, even though no comonomer was added. A structural characterization showed that the polymers contained methyl to hexyl branches and some longer branches. The effect of the polymerization conditions on branching was investigated through variations in the pressure and temperature of the polymerization. Depending on the degree and type of branching, polyethene was either quite amorphous or highly crystalline with a high melting temperature. The solid‐state structure of the catalyst dibromo‐N,N′‐1,2‐acenaphthylenediylidenebis[2,6‐bis(1‐methylethyl)benzeneamine]Ni(II) consisted of two centrosymmetrically related monomeric moieties, where Ni atoms were bridged by two bromide ligands. The Ni atom was five‐coordinated, with a square pyramidal coordination polyhedron. The sixth coordination site of the octahedral geometry was effectively blocked by the isopropyl groups of the 2,6‐C6H3(i‐Pr) substituents of the diimine ligand. In solution in the presence of MAO, the longer bridging Ni? Br bonds broke, and the complex dissociated to a monomeric species. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1426–1434, 2001 相似文献
19.
Mariagrazia Napoli Chiara Costabile Gabriella Cavallo Pasquale Longo 《Journal of polymer science. Part A, Polymer chemistry》2006,44(19):5525-5532
The behaviors of rac‐[CH2(3‐tert‐butyl‐1‐indenyl)2]ZrCl2 ( 1 ) and Cp2ZrCl2 ( 2 ) activated by methylaluminoxane in ethene/1,4‐pentadiene copolymerization are compared. In the presence of 1 , inserted methylene‐1,3‐cyclobutane units, a large number of crosslinks, and a small number of methylene‐1,3‐cyclohexane units are obtained. Differently, a polyethene containing only 1,3‐cyclohexane rings is achieved with 2 as the catalytic precursor. Polymer microstructures are compared with those obtained with 1 and 2 in ethene/1,6‐heptadiene copolymerization, which leads only to polyethene containing cyclohexane rings. A tentative rationalization of the experimental data is reported. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5525–5532, 2006 相似文献
20.
Daryoosh Beigzadeh Joo B. P. Soares Thomas A. Duever 《Macromolecular rapid communications》1999,20(10):541-545
The solution polymerization of ethylene in Isopar E in a semi-batch reactor using combined CGC-Ti and Et[Ind]2ZrCl2 catalysts was studied. Methylaluminoxane (MAO) and tris(pentafluorophenyl)borane were used as co-catalysts. Samples were analyzed by 13C NMR and gel permeation chromatography (GPC) for their branching content and molecular weight distribution. It was shown that there was an optimum ratio of CGC-Ti/Et[Ind]2ZrCl2 that maximizes the number of long-chain branches of the formed polyethylene. 相似文献