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  • 1
    Electronic Resource
    Electronic Resource
    An experimental study of the unperturbed chain dimensions of poly(tetramethyl-p-silphenylene-siloxane) (1993)
    Springer
    Polymer bulletin 31 (1993), S. 205-211 
    Details
    ISSN: 1436-2449
    Keywords: Intrinsic viscosities ; osmotic pressures ; unperturbed dimensions ; characteristic ratio ; chain stiffness ; poly(tetramethyl-p-silphenylene-siloxane)
    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 Experimental values of the characteristic ratio of the unperturbed dimensions of poly (tetramethyl-p-silphenylene-siloxane) were obtained from intrinsic viscosities and osmotic pressures. It was found that the characteristic ratio of this polymer is 1.55±0.30 when the phenylene group is treated as a virtual bond, and 4.51±0.40 when the individual bonds in the phenylene group are taken into account separately. This value is unexpectedly low, considering the usual stiffening effect of the p-phenylene group. Apparently this group can also have a “buffering” effect which decreases stiffness, by reducing interactions among the atoms or groups preceding it and succeeding it along the chain backbone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329967
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  • 2
    Electronic Resource
    Electronic Resource
    A polyamide-silica composite prepared by the sol-gel process (1993)
    Springer
    Polymer bulletin 31 (1993), S. 323-330 
    Details
    ISSN: 1436-2449
    Keywords: aromatic polyamides ; silica ; sol-gel process ; organic-inorganic hybrid materials ; gelation ; thermogravimetric analysis
    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 A new kind of organic-inorganic hybrid composite was prepared by means of the sol-gel process. The polymer employed was a mixed-isomer aromatic polyamide having good solubility and thermal stability. The silica constituting the inorganic phase was produced by the hydrolysis and condensation of tetramethoxysilane. The bonding between the phases involved aminophenyl-trimethoxysilane, in which the amino group can react with the phthaloyl chloride end-capped polymer, and the methoxysilane groups undergo hydrolysis. The composition of these composites was varied by changing the linear polymer chain length and relative amount of tetramethoxysilane. The gelation time was found to range from a few minutes to several days. Thermogravimetric analyses showed that decomposition starts at approximately 450 °C. Thin films cast from materials having a relatively high silica content were opaque and rigid, but those with low silica content were flexible and transparent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692959
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    Paper (German National Licenses)
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