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  • Polymer and Materials Science  (3)
  • decomposition of solids  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 863-877 
    ISSN: 1572-8943
    Keywords: Arrhenius parameters ; crystolysis ; decomposition of solids ; isothermal kinetics ; non-isothermal kinetics ; reaction mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An appraisal of the trends discerned in the recent literature concerned with solid-state decompositions suggests that this research area lacks a general theoretical framework and, hence, order in the subject is difficult to recognize. There have been surprisingly few reviews of the field. Many of the continuing flow of research publications may be of individual value, but most do not contribute to the overall development of the topic. For example, in many studies of reversible dissociations the sensitivity of rate characteristics to prevailing conditions is not discussed so that the fit of data to rate equations and the magnitudes of calculated Arrhenius parameters may be of empirical value only. Some studies report kinetic results without mechanistic discussions supported by complementary observations. Progress forward from an apparent state of stagnation depends upon more critical examination of the existing literature, coupled with better designed experiments to establish the reproducibility and reliability of kinetic conclusions. Techniques capable of providing insights into the bond redistribution steps that occur during reactions in crystals are also urgently needed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 1493-1503 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystals of the trans-octahedral complex Co(4-Vpy)4(NCS)2 on being heated below the melting point decompose with liberation of 4-vinylpyridine (Vpy) and concurrent polymerization of the free monomer. The two reactions have been followed by differential scanning calorimetry, thermogravimetry, and optical microscopy. Polymerization is inhibited by inclusion of hydroquinone during recrystallization of the complex. This has allowed the kinetic analysis of the decomposition and polymerization to be simplified. Isothermal mass-loss determinations under reduced pressure (10-2 torr), at various temperatures in the range 120-160°C, on hydroquinone-inhibited crystals corresponded to the loss of up to three molecules of vinylpyridine per molecule of starting complex. With uninhibited crystals over the same temperature range the total number of ligands lost was approximately two with a marked decrease near 175°C owing to rapid polymerization. Isothermal decomposition curves for inhibited and uninhibited crystals approximated to the Avrami-Erofeev equation. Values of n varied with temperature. Activation energies for decomposition and polymerization for both types of crystal were estimated from Arrhenius plots.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Propellants, Explosives, Pyrotechnics 14 (1989), S. 69-75 
    ISSN: 0721-3115
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An earlier thermo-analytical study of black powder, using small sample masses and slow heating rates, has been extended to an examination of the behaviour of black powder under the less-controlled conditions of ignition and combustion, by simultaneous measurement of temperature profiles and burning rates.Burning-rate against composition curves for various charcoal/KNO3, mixtures (sulphurless black powder) and for charcoal/KNO3, mixtures with various proportions of sulphur, were concave-down-type curves. The compositions of mixtures with maximum burning rates did not correspond with the compositions of mixtures with maximum enthalpy-of-reaction. Maximum temperatures of ∼1400°C were recorded. Burning rates were found to decrease with increasing particle size of the constituents: with increasing compaction of the mixtures, or when inert diluents or subsidiary fuels were added to the mixtures. Burning rates were also affected by moisture contents above 276, and failure of burning occurred at 〉15% moisture.
    Additional Material: 8 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-1: Polymer Chemistry 9 (1971), S. 2561-2574 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A survey of the solid-state polymerizability of 2- and 4-vinylpyridine (Vpy) complexes of divalent cobalt, nickel, copper, and zinc chlorides has been carried out. The influence of metal ion, ligand, coordination stereochemistry, and crystal structure is discussed. The tetrahedral modification of the complex Co(4-Vpy)2Cl2 has been found to undergo a particularly facile thermal polymerization below its melting point to yield high molecular weight poly-4-vinylpyridine. The polymer is shown to be conventional atactic head-to-tail poly-4-vinylpyridine. Thermogravimetric methods and optical microscopy have been used to study the thermal polymerization of single crystals of the complex. Results indicate a diffusion-controlled mechanism in which defective regions in the crystal act as nuclei for the polymerization.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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