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  • Chemistry  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Polymerization reaction with diphenylphosphoryl azide. Preparation of polyamides, polyureas and polyurethanes (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 1811-1820 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The preparation of various polyamides, polyureas and polyurethanes by polymerization reactions with diphenylphosphoryl azide (DPPA) was investigated. Various polyamides were obtained very conveniently by polymerization of aminocarboxylic acids or copolymerization of dicarboxylic acids and diamines. Polyureas were mainly obtained by conversion of dicarboxylic acids to acyl azides with DPPA and then to isocyanates, followed by copolymerization of these diisocyanates with diamines. Further, the polymerization of some aminocarboxylic acids that have an amino group of low nucleophilicity (such as p-aminobenzoic acid) was found to give polyureas instead of polyamides by direct polymerization. Polyurethanes were also obtained from dicarboxylic acids and diols through the Curtius rearrangement of acyl azides, similarly as in the polyurea preparations. The products were identified with the help of IR spectra and elemental analyses, and their molecular weights were evaluated viscometrically.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920815
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanical properties of solvolysis lignin-derived polyurethanes (1991)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 2 (1991), S. 41-47 
    Details
    ISSN: 1042-7147
    Keywords: Polyurethane ; Solvolysis lignin ; Tensile properties ; Diphenylmethane diisocyanate ; Crosslinking ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In order to study the tensile properties of solvolysis lignin polyurethanes, polyurethane (PU) films were prepared from the solvolysis lignin (SL)-polyethylene glycol (PEG)-diphenylmethane diisocyanate (MDI) system, and in addition to this further PU films were also prepared from the SL-MDI system. In the SL-PEG-MDI system, the SL content, the molecular weight of PEG and the NCO:OH ratio were varied in order to control the physical properties. The tensile stress and Young's modulus of the PUs of the SL-PEG-MDI type increased with increasing SL content and NCO:OH ratio. The tensile properties of the PUs from the SL-MDI system showed no NCO:OH ratio dependency; i.e. the mechanical properties of PUs are not influenced by the change in crosslinking. It is possible to control the tensile properties of PUs of the SL-PEG-MDI type by changing the content of PEG and SL at a constant NCO:OH ratio.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1991.220020106
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