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  • 1
    Electronic Resource
    Electronic Resource
    13C-NMR study of ethylene/1-hexene and ethylene/1-octene copolymers obtained using homogeneous catalysts (1995)
    Springer
    Polymer bulletin 34 (1995), S. 599-604 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary This study employed the 13C-NMR spectroscopy to investigate the influence of the increase of the comonomer concentration on the microstruture of ethylene/1-hexene and ethylene/1-octene copolymers obtained by the use of MeSiCp2ZrCl2, Cp2ZrCl2, Et[Ind]2ZrCl2 and [Ind]2ZrCl2 catalysts. For both comonomers butyl or hexyl branches were isolated between ethylene blocks. As the α-olefin concentration in the copolymer increased, butyl or hexyl branches became closer, some of them, separated by only one or two ethylene units. Incorporation of α-olefin in the copolymer was higher for the bridged catalysts, MeSiCp2ZrCl2, and Et[Ind]2ZrCl2 than for the unbridged ones. The α-olefin size did not seem to effect its reactivity towards ethylene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423357
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetic study of the reaction between hydroxylated polybutadienes and isocyanates. 1. Reaction with tolylene diisocyanate (TDI) (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 727-735 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A comparative kinetic study of the reaction of three different hydroxylated liquid polybutadienes (Mn ⋍ 3000)  -  R - 45M, R-45HT, and H-034 - and tolylene diisocyanate (TDI), was carried out in toluene solution. An analytical method was used to follow the kinetics of the reactions at four different temperatures. The reactions presented an apparent second-order rate law. In the second-order plots, a discontinuity was observed. The R-45M polybutadiene was about twice more reactive than R-45HT and H-034; these latter two polybutadienes presented similar reactivities.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240416
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  • 3
    Electronic Resource
    Electronic Resource
    Polymerization of styrene by diphenylzinc-additive systems (1996)
    Springer
    Polymer bulletin 37 (1996), S. 13-19 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Styrene was polymerized using combined systems of diphenylzinc, Ph2Zn, and metallocene compounds activated by methylaluminoxane, MAO. From the various metallocenes employed bis (indenyl) zirconium dichloride, Ind2ZrCl2, [isopropyl (cyclopentadienyl) (1-fluorenyl)] zirconiumdichloride, i-Pr (Flu) (Cp) ZrCl2, and bis (cyclopentadienyl) titanium dichloride, Cp2TiCl2, produced the larger amounts of polymer. Ph2Zn-Cp2TiCl2-MAO system gave polystyrene, PSt, whose DSC analysis indicated a major endotherm peak at 256°C. A butanone insoluble fraction of the polymer was separated from the crude PSt. The proportion of insoluble polymer depends on the metallocene employed and on the conversion to polymer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313813
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of the ethylene pressure on its reaction with 1-hexene, 1-octene and 4-methyl-1-pentene (1996)
    Springer
    Polymer bulletin 37 (1996), S. 469-474 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Copolymers of ethylene and 1-hexexe, 1-octene and 4-methyl-1-pentene were obtained using Et[In]2ZrCl2/MAO catalyst at various pressures. The increase of 1-hexene and 1-octene concentration in the feed increases catalyst activity(g/nZr.h.bar) and productivity(g/nZr.h). For 4-methyl-1-pentene the activity is independent on comonomer concentration. Increasing the ethylene pressure the productivity of the copolymerization increases and the activity shows a weak decay. Characterization of the copolymer shows that at higher pressure the cristallinity of the copolymers is higher due to lower comonomer incorporation. There is a good linear correlation of cristallinity with comonomer concentration in the feed for 1-hexene and 1-octene at a fixed pressure, but not for 4-methyl-1-pentene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00556807
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  • 5
    Electronic Resource
    Electronic Resource
    Optimization of olefin copolymerization: effects of reaction parameters on catalytic activity and properties (1998)
    Springer
    Polymer bulletin 40 (1998), S. 103-109 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. The copolymerization of ethylene with 1-hexene using Et[Ind]2ZrCl2/MAO as catalyst was studied by multivariate methods. Three complete factorial designs were performed to study the influence of 1-hexene concentration, reaction temperature and [Al]/[Zr] ratio on catalytic activity, copolymer viscosity, crystallinity and melting point. Since the [Al]/[Zr] ratio has a small effect on the catalytic activity, a fourth design with 1-hexene and temperature was developed, giving higher catalytic activities. Temperature and 1-hexene concentration were the main effects found in the system. A second order effect arising from 1-hexene versus [Al]/[Zr] ratio was also detected. Polymer viscosity, crystallinity and melting points decreased with 1-hexene concentration. Viscosity decreased with temperature whereas crystallinity increased when the temperature was raised from 30 to 60 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002890050230
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of ethylene-1-hexene copolymers using homogeneous Ziegler-Natta catalysts (1995)
    Springer
    Polymer bulletin 35 (1995), S. 299-306 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary This study investigated the copolymerization of ethylene with 1-hexene using the homogeneous Et[Ind]2ZrCl2 and [Ind]2ZrCl2 catalysts. The Et[Ind]2ZrCl2 catalyst gave a higher catalytic activity than the [Ind]2ZrCl2 and also showed a better incorporation of 1-hexene for the same comonomer concentration in the feed. Thermal analysis (DSC) and viscosity measurements showed that an increase of the 1-hexene incorporated in the copolymer results in a decrease of the melting point, crystallinity and molecular weight of the polymer formed. The reactivity ratios for ethylene and 1-hexene confirmed the more successful incorporation of the comonomer for the polymerization catalyzed by Et[Ind]2ZrCl2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00963127
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  • 7
    Electronic Resource
    Electronic Resource
    Modification of poly(propylene) through grafting with dimethyl itaconate in solution (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 2495-2500 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Functionalization of isotactic poly(propylene) (PP) with dimethyl itaconate (DMI) as functional polar monomer using 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (L101) as radical initiator was carried out in both boiling xylene and decalin as solvent media. The effect of DMI and the initiator concentration on the extent of grafting was studied by varying reaction time and temperature. It was found that temperature affects the percentage of DMI grafted onto PP, which is slightly higher for reactions carried out in xylene than in decalin. The results also show that the amount of DMI incorporated is proportional to the initial DMI and initiator concentrations used in the grafting reaction up to certain concentrations, and thereafter a decrease in the percentage of grafting (G in wt.-%) was found. The maximum value of grafting obtained was 0.7 wt.-%. The melt flow index (MFI) values increase with increasing initial amount of initiator used in the grafting reaction. The degradation of the PP chain is higher when xylene is used as solvent. MFI values of 20-100 were found for modified PP compared with 11.4 for the unmodified polymer.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Functionalization of polypropylene by grafting with itaconic acid (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 17 (1996), S. 577-582 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Grafting of polypropylene was carried out in both boiling xylene and decalin as solvent medium with itaconic acid (2-methylenesuccinic acid) as functional polar monomer using 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (Lupersol 101) as radical initiator. It was found that the temperature influenced the percentage of monomer grafted onto polypropylene and that the amount of monomer incorporated was practically constant after 5 min. The results also show that the amount of monomer incorporated is proportional to the initial monomer concentration used in the grafting reaction, although for higher initiator concentrations a reduction in the percentage of grafting was found.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1996.030170811
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  • 9
    Electronic Resource
    Electronic Resource
    The influence of the comonomer in the copolymerization of ethylene with α-olefins using C2H4[ind]2ZrCl2/methylaluminoxane as catalyst system (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 3091-3098 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolymers based on ethylene with different incorporations of 1-hexene, 1-octene and 1-decene were obtained. There is not any marked variation of activity when different metallocenes were tested. The type and the concentration of the comonomer in the feed do not have a strong influence on the catalytic activity of the system, but the presence of the comonomer increases the activity compared with that in the absence of it. From 13C NMR it was found that below 8% of comonomer incorporated the comonomer units appear isolated between polyethylene blocks, sequences of the type ethylene-comonomer-ethylene-comonomer appear only above 8% of comonomer incorporated for all the systems studied. The reactivity of the comonomers for this particular system shows that the size of the lateral chain influences the percentage of comonomer incorporated, 1-hexene being the highest one incorporated. The crystallinity of the copolymers exerts a linear relation with the amount of comonomer incorporated, and it is independent of lateral chain lengths. The molecular weight of the copolymers obtained was found to be dependent on the comonomer concentration in the feed, showing that there is a transfer reaction with the comonomer. The polydispersity (M̄w/M̄n) of the copolymers is rather narrow and dependent on the concentration of the comonomer incorporated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1996.021971003
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  • 10
    Electronic Resource
    Electronic Resource
    The influence of the transition metal and the heteroatomic-bridge on the action of metallocene/methyl aluminoxane catalysts in ethylene polymerization and on the properties of the polymer (1995)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 16 (1995), S. 357-362 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This work reports a comparative study of the catalytic behaviour for a series of metallocenes derived from Ti, Zr, Hf and Nb, which after activation with methylaluminoxane can polymerize ethylene. Results show that the Zr metallocene with a —(CH3)2Si—Bridge presents the highest activity, and the metallocenes based on Hf and Nb do not show any significant activity under the tested conditions.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1995.030160503
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