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  • 1
    Electronic Resource
    Electronic Resource
    Free-radical reactions of high molecular weight isoalkanes (1987)
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 26 (1987), S. 1633-1638 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie00068a023
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  • 2
    Electronic Resource
    Electronic Resource
    13C NMR spectra of propylene/1-hexene copolymers (1991)
    s.l. : American Chemical Society
    Macromolecules 24 (1991), S. 2632-2633 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00009a075
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  • 3
    Electronic Resource
    Electronic Resource
    Relative reactivities of alkanes in multi-component catalytic cracking reactions (1993)
    Springer
    Catalysis letters 19 (1993), S. 181-187 
    Details
    ISSN: 1572-879X
    Keywords: Catalytic cracking ; alkane cracking ; isoalkane cracking ; alkane reactivities in catalytic cracking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An experimental technique is discussed for measuring relative reactivities of alkanes in the catalytic cracking of multi-component hydrocarbon mixtures over a heterogeneous, Y-zeolitebased catalyst at 250–350 °C. With the technique, ca. 0.1 μl of an alkane mixture is evaporated and contacted with a catalyst, after which the mixture of reaction products and the unreacted feed enters the chromatographic column and is immediately analyzed. The technique is used to measure relative reactivities of 21 alkanes in a single experiment. The principal results of these experiments are similar to the results of single-component cracking: alkane reactivity rapidly increases with the increase of the carbon number, and methyl-branched alkanes are more reactive than linear alkanes. However, the variations in alkane reactivities as a function of their molecular weight and skeleton structure differ very significantly between single- and multicomponent experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00771753
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of ethylene homopolymerization and copolymerization reactions with heterogeneous Ti-based Ziegler–Natta catalysts (1999)
    Springer
    Topics in catalysis 7 (1999), S. 69-88 
    Details
    ISSN: 1572-9028
    Keywords: Ziegler–Natta catalysts ; titanium-based polymerization catalysts ; ethylene polymerization reactions ; polymerization kinetics ; deuterium effect on ethylene polymerization ; α-olefin effect on ethylene polymerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A detailed kinetic analysis of ethylene homopolymerization reactions and its copolymerization reactions with 1-hexene with a supported Ti-based Ziegler–Natta catalyst (reactions in the absence and the presence of hydrogen) shows a number of distinct kinetic features which are interpreted as a manifestation of multi-site catalysis; the catalyst contains several types of polymerization centers which differ in stability and formation rates, the molecular weight of polymers they produce, and in their response to the presence of α-olefins and hydrogen. All these effects require introduction of a special kinetic mechanism which postulates an unusually low activity of growing polymer chains containing one ethylene unit, the Ti–C2H5 group, in the ethylene insertion reaction into the Ti–C bond. This peculiarity of the Ti–C2H5 group, which is probably caused by its β-agostic stabilization, predicts two kinetic/chemical features of ethylene polymerization reactions which have not been described yet, the deuterium effect on the homopolymer structure and the activation effect of α-olefins on chain initiation. Both effects were confirmed experimentally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019199330327
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  • 5
    Electronic Resource
    Electronic Resource
    Dual-functional catalysis for ethylene polymerization to branched polyethylene. II. Kinetics of ethylene polymerization with a mixed homogeneous-heterogeneous Ziegler-Natta catalyst system (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1069-1084 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The previous paper in this series described several catalytic systems which can be used for simultaneous ethylene dimerization to 1-butene and copolymerization of the in situ-formed olefin with ethylene to form branched polyethylene. Such catalytic systems allow the synthesis of linear low-density polyethylene from a single monomer source. This article presents a more detailed description of one of the dual-functional catalyst systems studied, a mixed homogeneous-heterogeneous Ziegler-Natta catalyst, Al(C2H2)3-Ti(Oi-C3H7)4-TiCl4/MgCl2/polyethylene, at 90°C. Discussed are kinetics of ethylene dimerization with the soluble component, Al(C2H5)3-Ti(Oi-C3H7)4, and the effects of aluminum alkoxides on the system. Addition of the ethylene dimerization catalyst to the solid component, Al(C2H5)3-TiCl4/MgCl2/polyethylene, results in a partial decrease in polymerization activity. Some of the decrease can be attributed to the presence of 1-butene in the reaction medium. Measurement of the reactivity ratio kEE/kEB for two catalytic systems, the solid component and the title dual-functional catalyst, demonstrated that the presence of the dimerization component results in a twofold increase in the reactivity ratio, from 20 to ca. 40.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240601
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  • 6
    Electronic Resource
    Electronic Resource
    Oligomerization of ethylene with a homogeneous sulfonated nickel ylide-aluminum alkoxide catalyst (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 147-155 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various organoaluminum compounds strongly affect reactivity of a sulfonated nickel ylide complex in its reactions with ethylene. The complex, if used alone, is an active single-component catalyst for ethylene oligomerization to linear 1-alkenes. Al(C2H5)3 and tetraethylaluminoxane completely deactivate the catalyst by reducing it to Ni(O). Alkylaluminum halides, such as Al(C2H5)2Cl and Al(C2H5)Cl2, convert the nickel complex into a very active catalyst for ethylene dimerization to mixtures of butenes. Aluminum alkoxides, e.g., Al(C2H5)2OC2H5, AlC2H5(OC2H5)2, and Al(OC2H5)3, significantly increase oligomerization activity by a factor of 20-100. The distribution of 1-alkenes (in the C4—C40 + range) produced with the sulfonated nickel ylide-aluminum alkoxide catalyst follows the Flory molecular weight distribution law. The ratio of the chain termination to chain propagation rate constants is ca. 0.3 and is not temperature-sensitive in the 50-120°C range. Kinetic analysis of the ethylene oligomerization reaction with the binary catalytic system showed that the number of active centers is proportional to the nickel complex concentration. The effective activation energy of ethylene oligomerization with the catalyst is ca. 27 kJ/mol. The oligomerization catalysts loose their activity in time. The activity decay follows the first-order kinetic law. The rate of the decay increases with increasing temperature and is caused mainly by the intrinsic instability of active species.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080270113
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  • 7
    Electronic Resource
    Electronic Resource
    Dual functional catalysis for ethylene polymerization to branched polyethylene. I. Evaluation of catalytic systems (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 3027-3042 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of low-density polyethylene, that is, a density of less than 0.925 g/cm3, has traditionally been accomplished by the use of free-radical initiators at high ethylene pressures or of an alpha olefin comonomer such as 1-butene at lower pressures. We investigated an alternative route to branched, low-density polyethylene with a single monomer, ethylene, as the feed in conjunction with multicomponent catalyst systems capable of in situ dimerization of ethylene and subsequent copolymerization to produce low-density polyethylene. This article discusses the details of the evaluation of a number of dual-functional systems based on Ziegler-Natta catalysts. Specific, well defined, dual-functional catalyst systems which could easily produce branched, low-density polyethylene with levels of 20-30 branches per 1000 carbon atoms were developed. Variations in the relative number of component catalysts resulted in systematic, predictable changes in the properties of the polyethylene produced, which demonstrated the utility of the dual-functional catalyst concept.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.170221125
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