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  • 1975-1979  (11)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 256 (1978), S. 1152-1152 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 107 (1976), S. 1315-1326 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reactivity ratios for the vinyl acetate-divinyl adipate system are determined. Both valuesr V Ac andr DV A are near to unity. The reactivity of the pendent double bond is very low and soluble polymers are formed far over the critical conversion calculated with anr-value of the pendent double bonds equal to unity. Contrary to this a high portion of intramolecular cyclization occurs, presumably leading to chain units of the type amounting to 10% of the total number of divinyl adipate units in the chain in systems with an initial monomer concentration of 95% and to 23% in systems with a monomer concentration of 50%. The reactivity ratio of the pendent double bond is estimated. The main reason for the high conversion for gel formation is the low rate of intermolecular reaction of pendent double bonds. In this respect cyclization plays a minor role.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 109 (1978), S. 215-219 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The weight average degree of polymerization of vinyl acetate-divinyl adipate copolymers (low content of divinyl adipate) is measured at conversions up to 22%. From thisk 13/k 12 (rate constants of reaction of growing radicals with pendent double bonds and divinyl adipate double bonds, respectively) is calculated to be 0.28. A quantitative relation for the gel point (critical conversion) is given.
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  • 4
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 73-77 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The products of the reaction of 2-cyano-2-propyl radicals with 1,4-benzoquinone in toluene solution have been investigated by 1H NMR spectroscopy and mass spectroscopy. In agreement with the findings of Bickel and Waters the main reaction products are the hydroquinone monoether 1 and the hydroquinone diether 2. In addition two ringsubstituted products, 5 and 6, have been obtained. The structures 3 and 4, which have been proposed for the main products by Yassin and Rizk, are shown to be in error.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The reaction of 1-phenylethyl radicals (originating from the thermal decomposition of 1,1′-diphenylazoethane) with 1,4-benzoquinone (3) and tetrachloro-1,4-benzoquinone (8), respectively, in either case yields the mono(1-phenylethyl) ether of the corresponding hydroquinone as the main product. In addition, in the reaction with 3, the diether of the hydroquinone [1,4-bis(1-phenylethyloxy)benzene], and in the reaction with 8a small amount of a ring substituted product, 2-(1-phenylethyl)-3,5,6-trichlorobenzoquinone, occur as side products. The formation of larger amounts of further ring-substituted products can be excluded in both cases. These results complete and support earlier conclusions from the interaction of quinones with polymerizing styrene which suggested that the C=O double bond is the site of attack of the polystyryl radicals. Furthermore, the formation and function of tetrachlorohydroquinone during the polymerization of styrene in presence of 8 is elucidated.
    Notes: Bei der Reaktion von 1-Phenyläthylradikalen (aus dem thermischen Zerfall von 1,1′-Diphenylazoäthan) mit 1,4-Benzochinon (3) bzw. Tetrachlor-1,4-benzochinon (8) ist das Hauptprodukt in jedem Fall der Mono (1-phenyläthyl)äther des entsprechenden Hydrochinons. Zusätzlich treten bei der Reaktion mit 3 noch der Diäther [1,4-Bis(1-phenyläthyloxy)-benzol] und bei der Reaktion mit 8 in geringem Ausmaß ein Kernsubstitutionsprodukt, das 2-(1-Phenyläthyl)-3,5,6-trichlorbenzochinon, als Nebenprodukte auf. Die Bildung größerer Anteile an sonstigen Kernsubstitutionsprodukten läßt sich in beiden Fällen mit Sicherheit ausschließen. Diese Ergebnisse ergänzen und unterstützen die aus den Ergebnissen bei der Einwirkung von Chinonen auf polymerisierendes Styrol gezogene Schlußfolgerung, daß der Angriff der Polystyrylradikale auf die C=O-Doppelbindungen erfolgt. Darüber hinaus wurde Bildungsweise und Funktion des bei der Polymerisation von Styrol in Gegenwart von 8 auftretenden Tetrachlorhydrochinons geklärt.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 2249-2255 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The constant of chain transfer to carbon tetrabromide in the polymerization of styrene has been redetermined by directly measuring the consumption of the chain transfer agent using a GC-technique and simultaneously evaluating the conversion of monomer to polymer. Values of 250 (at 60°C) and 185 (at 95°C) have been obtained by this method. These values agree in order of magnitude with those recently obtained by Thomson and Walters from the determination of polymer molecular weights and, accordingly, exceed the values previously reported by approximately two powers of ten. An analysis of the limiting viscosity numbers of the polymers prepared in presence of carbon tetrabromide shows an excellent agreement with these new high values of the chain transfer constant of carbon tetrabromide. For the constant of chain transfer to carbon tetrabromide in the polymerization of vinyl acetate a value of 6·103 has been obtained at 60°C, which again is two to three orders of magnitude higher than those values given previously.
    Additional Material: 3 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 2929-2935 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In free radical polymerization the polymers usually represent a mixture consisting of molecules from one (degree of coupling k = 1) and two (k = 2) independently grown chains. In case the chain lengths at the moment of stabilization obey the same most probable Schulz-Flory distribution over the total conversion interval (as e.g. at low conversions) the molecular weight distribution (m. w. d.) is a superposition of two Schulz distributions with degrees of coupling k = 1, and k = 2, respectively. Frequently, however, this m. w. d. has been described by a Schulz distribution with a non-integer k. It is pointed out that the deviations of such a representation of the m. w. d. from the correct one may not always be negligible. Furthermore, there is no unique way to ascribe a degree of coupling k to such an m. w. d. Thus, the use of a non-integer k should be avoided for the characterization of these polymers, especially when the interrelations between the m. w. d. and the kinetic parameters are to be discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanism of the bimolecular reaction between the model radicals for polystyryl: 1-phenylethyl, 1-phenylpropyl, and 1,3-diphenylpropyl radical is investigated by means of gas chromatography. The radicals are generated either at 80°C by thermal or at 20°C by photochemical decomposition of the corresponding azoalkanes in benzene solution. At 80°C 7,5% of the 1-phenylethyl radicals, 12,9% of the 1-phenylpropyl radicals, and 13,5% of the 1,3-diphenylpropyl radicals undergo disproportionation. Since the structure of these model radicals approaches that of the growing polystyrene chain in this order one may expect polystyryl radicals to disproportionate to about the same extent as 1,3-diphenylpropyl radicals. In photolysis experiments evidence for ortho coupling of 1-phenylalkyl radicals is found. Photoisomerisation of this ortho coupling product leads to the formation of a small amount of a thermally stable unsymmetrical dimer.
    Additional Material: 1 Ill.
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  • 10
    Publication Date: 1978-11-01
    Print ISSN: 0372-820X
    Electronic ISSN: 1435-1536
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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