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  • 1990-1994  (2)
  • 1990  (2)
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  • 1990-1994  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Direct monitoring of cationic polymerization by temperature, conductivity and permittivity measurements (1990)
    Springer
    Polymer bulletin 23 (1990), S. 75-82 
    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 Direct monitoring of cationic polymerization was accomplished by simultaneous measurement of the average dielectric constant, representing the dipoles, of the conductivity, produced by unpaired ions, and of the temperature, characteristic for reaction rate. The ionogenic equilibria during the living polymerization of isobutylene by 1, 3, 5-tris(2-methoxy-2-propyl)benzen/BCl3 in CH2Cl2 at-25°C were demonstrated. Temperature, resistance and capacitance were measured directly in the reaction mixture by a specially designed instrument. Both the conductivity and the average dielectric constant change characteristically during the living polymerization, indicating the presence and simultaneous change of unpaired ions and strongly polarized species. The differences between the AMI, and the aging technique were demonstrated and explained. In the latter case slow initiation was observed due to the methoxy-chlorine exchange caused by a reaction with BCl3. The applied direct monitoring method helps to understand the role of polarized and ionic species in polymerizations and related processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00983967
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Investigation of 1,3,5-tris(2-metoxypropane)benzene/BCl3 initiated living isobutylene polymerization by C13 and B11 NMR spectroscopy (1990)
    Springer
    Polymer bulletin 23 (1990), S. 335-340 
    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 The living carbocationic polymerization of isobutylene initiated by 1,3,5-tris(2-methoxypropane) benzene (TriCumOMe)/BCl3 system was investigated by C13 and B11 NMR spectroscopy. The reaction between the TriCumOMe and BCl3 at-30°C in CH2Cl2 after 15 mins reaction time resulted in 1,3,5-tris(2-chloropropane) benzene (TriCumCl) and methyl-dichloroboronite (BCl2OMe). The same system in the presence of isobutylene yielded three-arm star, chlorine terminated telechelic polyisobutylene and BCl2OMe. No counterions, i.e., BCl3OMe⊝, BCl 4 ⊝ , or neutral boron complexes, e.g., TriCumOMe, 3BCl3 could be detected. The simultaneous measurement of static permittivity (direct monitoring method) showed different reaction rate patterns in the case of AMI method, and when the TriCumOMe+BCl3 mixture was aged and the polymerization was started by isobutylene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01032450
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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