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  • 1965-1969  (2)
  • 1965  (2)
Material
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  • 1965-1969  (2)
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 9 (1965), S. 2965-2983 
    ISSN: 0021-8995
    Keywords: 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 , Physics
    Notes: Stress relaxation and swelling measurements were carried out and the data used for determination of the effective crosslink densities of one- and two-component urethane sealants. These crosslink densities were compared with calculated values. The results were correlated with the structure of the urethane sealants. Two sealant structures were evaluated: one based on mixtures of triol prepolymers and diol adducts, and the other on triol adducts. Both one- and two-component sealants were investigated. The two-component sealants had a tendency to be undercured even when quite effective catalysts were used. The one-component sealants, because of moisture cure and of biuret or allophanate formation, produced in most cases a higher crosslink density than the calculated triol crosslink density. It was also observed that curing efficiencies of the two-component sealants decreased with increasing molecular weight per crosslink. Deviations from these correlations were noted when a short poly(oxypropylene)glycol of 400 molecular weight was used for curing purposes. These anomalies were detected by stress relaxation and by swelling techniques as well as by measurement of torsional modulus. Stress relaxation studies were carried out to determine the influence of temperature, catalysts, and strain on stress decay. The results again indicated that the two-component sealants did not cure completely, and that the type of catalyst had a significant influence on degradation of urethane sealants at elevated temperatures.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0021-8995
    Keywords: 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 , Physics
    Notes: A study has been conducted of the kinetics of the reactions of primary and secondary alcohols with phenyl isocyanate in the presence of metal catalysts. It has been determined that the type and concentration of metal catalyst, the structure of the alcohols, and the type of solvent play an important role in the reaction rates and ratios of rate constants. Catalysis by lead naphthenate increased the reaction rates of 2-methoxy-l-propanol and 1-methoxy-2-propanol more than 3-methoxy-1-propanol, whereas catalysis by dibutyltin dilaurate enhanced the reaction rates of 3-methoxy-1-propanol more than those of 2-methoxy-1-propanol and of 1-methoxy-2-propanol. Dibutyltin dilaurate has been found to impart a high ratio of Kprimary/Ksecondary, where the primary alcohol was 3-methoxy-1-propanol and the secondary alcohol was 1-methoxy-2-propanol. Determinations of mixtures in toluene solutions containing up to 75%, of 3-methoxy-1-propanol were made with good accuracy.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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