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  • Polymer and Materials Science  (2)
  • thermal stability  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Evaluation of the thermal stability of some nonlinear optical chromophores (1996)
    Springer
    Journal of thermal analysis and calorimetry 46 (1996), S. 1133-1150 
    Details
    ISSN: 1572-8943
    Keywords: NLO chromophores ; photorefractive materials ; TGA/MS ; thermal stability ; thermogravimetric analysis-mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Optical data storage is poised to benefit from a new class of advanced polymeric materials engineered to exhibit photorefractivity. Likewise, the transmission and processing of data will also benefit from a related class of materials with electro-optic activity. Organic chromophores are critical constituents of these materials which function due to a change of index of refraction in response to an electric field. However, a number of materials and processing problems remain to be solved before devices incorporating these optically nonlinear chromophores are practical. For example, for electrooptical applications the NLO waveguide should be able to withstand short duration processing temperatures in excess of 300°C and long duration use temperatures of at least 80°C. The requirement for thermochemical stability follows from the need to implement highT g matrices to provide stability of the orientational or polar order required for long-term device performance and reliability. As a result, the thermal stability of chromophores is now more closely evaluated in addition to their transparency and optical nonlinearity properties. Some chromophore classes, such as the azo dyes studied here, have attractive properties for these applications but further enhancements in overall properties are needed. Identification of the fundamental chemical processes in thermal decomposition of these dyes should lead to introduction of structural changes which provide better stability. Here thermogravimetric analysis (TGA) coupled with mass spectrometry (TGA/MS) is used to provide an assay of thermochemical stability with an added benefit that insight into the mechanisms of thermal decomposition may by identified. In this initial study diaryl substitution of the amine in derivatives of 4-amino-4′-nitroazobenzene was observed to greatly enhance thermal stability relative to dialkyl substitution. Substitution of phenyl for alkyl eliminates structural features involved in the most facile degradation mechanism available to the alkyl derivative.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01983625
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The pyrolytic characterization of a surfactant/polymer/ceramic composite system using combined thermogravimetric analysis-mass spectrometry (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 301-309 
    Details
    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: An experimental technique of combined thermogravimetric analysis (TGA)-mass spectrometry (MS) was used to study the pyrolysis process during binder removal from a ceramic/binder system. The effect of a fluorocarbon surfactant on the pyrolysis process was also investigated and it was discovered that the surfactant had no significant effect on pyrolysis. A simple paraffin binder system was implemented so as to enhance the effects of the surfactant. The identification of the fragments created during pyrolysis is also discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410122
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A methodology for characterizing reactive coatings: Time-temperature-transformation (TTT) analysis of the competition between cure, evaporation, and thermal degradation for an epoxy-phenolic system (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 803-816 
    Details
    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 methodology, in terms of a macroscopic isothermal time-temperature-transformation (TTT) diagram, is presented for characterizing the changes that occur isothermally in a reactive thermosetting system in which evaporation, cure, and thermal degradation occur. Iso-weight loss contours show the progress of the loss of volatile material (mostly solvent). The gelation contour corresponds to the macroscopic viscosity rising to a definite level. The vitrification contour corresponds to the glass transition temperature (Tg) rising to the temperature of cure (Tcure). Iso-Tg contours show the progress of cure in terms of the easily measured Tg (rather than chemical conversion). The iso-Tg contours also show the influence of thermal degradation competing with cure. Degradation is responsible for difficulties in assigning the glass transition temperature of the fully cured material (i.e., Tg∞).
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070370316
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    Paper (German National Licenses)
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