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  • 2020-2024
  • 1965-1969  (4)
  • 1935-1939
  • 1920-1924
  • Physics  (4)
  • 1
    Digitale Medien
    Digitale Medien
    Polymer reactions. II. Thermal decomposition of polyethylene hydroperoxide (1968)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 6 (1968), S. 375-379 
    Details
    ISSN: 0449-296X
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Polyethylene hydroperoxide (PEH) was prepared by low-temperature autoxidation initiated by AIBN. Over 85% of the total hydroperoxyl groups decompose by a rapid process, the remainder dissociate at about one-tenth of that rate. The results are the same whether PEH is decomposed in solution or in the solid state. Large amounts of scavenger have no effect on these decompositions; there is no radical-induced processes. The results suggest mechanisms of decomposition involving neighboring group assistance.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1968.150060207
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  • 2
    Digitale Medien
    Digitale Medien
    Polymer reactions. V. Kinetics of autoxidation of polypropylene (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 3091-3101 
    Details
    ISSN: 0449-296X
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate constants for the autoxidation of polypropylene were determined by a combined ESR, volumetric, and chemical method. The values of ki, kp, and kt at 110°C. are 3 × 10-4 sec.-1, 1.9 l./mole-sec., and 3 × 106 l./mole-sec., respectively. The values of ki and its activation energy are the same as those for the decomposition of polypropylene hydroperoxide, thus identifying the latter as the principal initiation process. The values of the temperature-independent kt suggest that secondary peroxy radicals are the terminating species. The rate constants are compared with rate constant ratios for initiated autoxidations of squalane and other related systems.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1967.150051210
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  • 3
    Digitale Medien
    Digitale Medien
    Polymer reactions. IV. Thermal decomposition of polypropylene hydroperoxides (1968)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 6 (1968), S. 393-402 
    Details
    ISSN: 0449-296X
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The thermal decomposition of polypropylene hydroperoxide (PPH) consists of two consecutive reactions. The initial, faster reaction has rates up to 60 times that of the slower process. The former is largely suppressed by the addition of an excess of 2,6-di-tert-butyl-p-cresol. The course of reaction is the same in either solid state or in solution. The results are consistent with an intramolecular radical-induced mechanism for the initial reaction. This faster reaction consumes about 70-95% of the total hydroperoxides. The decomposition of PPH yields a maximum of about 1.8 radicals. Samples prepared from crystalline and amorphous polypropylenes have identical decomposition kinetics.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1968.150060209
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  • 4
    Digitale Medien
    Digitale Medien
    Polymer reactions. III. Structure of polypropylene hydroperoxide (1968)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 6 (1968), S. 381-392 
    Details
    ISSN: 0449-296X
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Oxidation of polypropylene introduces hydroperoxide groups into the polymer. Infrared spectroscopy has determined that more than 90% of these groups are intramolecularly hydrogen bonded. The sequential lengths and sequence distributions of these neighboring hydroperoxides were estimated from the electronic spectra of the polyenes derived from the polypropylene hydroperoxide by two methods: (1) reduction, acetylation, and pyrolysis, and (2) reduction and dehydration. The results indicate that all the hydroperoxide groups are present in sequences of length two and greater. Intramolecular hydrogen abstraction during oxidation could account for the formation of these neighboring hydroperoxides.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1968.150060208
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