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  • 1960-1964  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 56 (1962), S. 27-32 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Isotactic polyvinyl isobutyl ether was obtained using chromium trioxide as catalyst at elevated temperatures, even at 80°C. Polymerization was carried out in a heterogeneous system. A stirring device to mill the catalyst is necessary to obtain polymer which has a high crystalline fraction. The crystalline fraction, whose melting point is over 140°C., was separated by extracting the amorphous portion with methyl ethyl ketone, and was between 20 and 30% weight of the total polymer. In this connection, other transition metal oxides were examined but chromium oxides of lower valence than 6 had little activity toward polymerization. Moreover, molybdenum trioxide, vanadium pentoxide, and nickel monoxide showed activity toward polymerization, but the polymers obtained with these catalysts had no crystalline fraction.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 1 (1963), S. 2371-2381 
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Magnesium compounds, especially Grignard reagents were studied as catalysts in the polymerization of vinyl ethers. The Grignard reagent and diethyl magnesium possessed no activity for polymerization of vinyl ether. However, if the Grignard reagent is combined with some sort of third substances, it shows good activity. For these substances, oxygen, aldehydes, some metal oxides, and halogenated hydrocarbons seemed to be effective. The molecular weight of the polyvinyl ether obtained from this combined catalyst system is markedly higher than those of polymers obtained with the Friedel-Crafts type of catalyst, but the polymer of vinyl ether obtained from this mixed catalyst possesses little crystalline structure. The possible mechanism of the polymerization with this mixed catalyst is thought to be a cationic initiation type, because the true active species are regarded to be intermediate compounds which are analogous to magnesium halides or alkoxymagnesium halides. In this connection, alkoxymagnesium halides and magnesium oxide were examined. They had a good activity for polymerization but did not yield a high polymer.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 1 (1963), S. 3277-3288 
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Stereospecific polymerization of vinyl alkyl ether was studied; various kinds of compounds, such as metal oxides, metal halides, metal oxyhalides, metal sulfate complexes and organometallic compounds-Lewis acid complexes, being used at low temperature or room temperature. The relationship between the structures of catalysts and the stereoregularities of polymers is discussed, and it is found that tetrahedral compounds which have one active edge are especially useful for making the stereoregular polymers at room temperature. Also, the shorter the length of active edge, the more suitable the catalyst is for stereospecific polymerization. On the basis of these experimental results, a mechanism of stereospecific polymerization of vinyl alkyl ether is proposed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 1 (1963), S. 1937-1946 
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An attempt was made to summarize the activity of magnesium halides in the polymerization of vinyl ethers. Bulk polymerization was carried out at temperatures of 0-80°C. Methyl, ethyl, isopropyl, and isobutyl vinyl ethers were used as monomers, and the relative reactivities of these monomers were compared. Except for the fluoride, magnesium halides had mild activity. Within a given group, the overall activation energies of polymerization decrease with increasing weight of halogen. On the other hand, the molecular weight of polyvinyl ethers obtained from this group of catalysts increases with decreasing weight of halogen. In addition, some differences were observed between the diethyl ether complex and the dioxane complex of magnesium bromide.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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