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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1341-1355 
    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: Diphenylguanidine acceleration of sulfuration of natural rubber both in the presence and absence of dicumyl peroxide (DCP) has been studied. DPG enhances the rate of decomposition of DCP, and the crosslinking maxima due to DCP are lowered by DPG to some extent, which increases with the concentration up to a limiting value. The rate of sulfur decrease is very high and is dependent on DPG concentration but practically independent of the presence of ZnO and stearic acid. It is observed that with constant level of DCP and sulfur, crosslinking increases with the increase of DPG concentration and finally becomes additive when the molar proportion of DPG: S8 approximately equals 1:1. In presence of ZnO and stearic acid, with each increment of DCP concentration crosslinking is retarded for both systems. Mechanisms have been suggested in terms of polar and radical process.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 97 (1966), S. 174-188 
    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: In der vorliegenden Abhandlung wird über die Abhängigkeit der Beschleunigung der Vulkanisation von gebleichtem Krepp (Naturgummi) und von nichtpigmentiertem Styrol-Butadien-Gummi von der Konzentration an 2-Mercapto-benzthiazol (MTB) als Beschleuniger berichtet. Es wurde gefunden, daß die Menge der Abnahme an freiem Schwefel und die Zunahme der Vernetzungsdichte annähernd proportional der 0,8 ten bzw. 0,9ten Potenz der Konzentration des Beschleunigers sind. Es wurde weiter gefunden, daß die Abnahme an freiem 2-Mercapto-benzthiazol (MBT) dem Gesetz der ersten Reaktionsordnung gehorcht und daß sich bereits während des Zusammenmischens ungefähr 6-10% des MBT mit dem Gummi verbinden. Die optimalen Vulkanisationszeiten, die nach verschiedenen Methoden erhalten wurden (aus dem Abfallen der Menge des freien Schwefels, der Zunahme der Vernetzungsdichte, der Zugfestigkeit und Messungen des Moduls), stimmen annähernd überein.
    Notes: The dependence of the rate of accelerated vulcanization of pale crepe and non-pigmented styrene-butadiene rubber on the concentration of 2-mercaptobenzothiazole (MBT) accelerator has been reported in this paper. The rate of decrease of free sulfur and increase of cross-linking density have been found to be approximately proportional to the (concentration of accelerator)n where n is 0.8 and 0.9. The decrease of free MBT is found to follow a first order reaction with respect to time of cure and about 6-10% of MBT is found to combine with rubber during mixing. The optimum times of cure as obtained from decrease of free sulphur, increase of cross-linking density, tensile strength, and modulus plots against time of cure fall within agreeable range.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 109 (1967), S. 217-230 
    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: Die Vernetzerwirksamkeit von Dicumylperoxid bei Styrol-Butadiengummi (SBR-1507) wurde mit Hilfe von Quellungsmessungen erfaßt. Die erhaltenen Werte sind 2,5 bzw. 5 für ungereinigten bzw. gereinigten SBR. Der niedrigere Wert im ersten Fall wurde der Vernichtung von Peroxyradikalen durch Antioxydantien im Gummi zugeschrieben. Die physikalischen Vernetzungen, die beim gereinigten SBR auf Kettenverknäuelungen zurückzuführen sind, betragen 0,14.10-4 Mol/g Gummi (oder 0,07.10-4 Vernetzungsstellen der Kettenverknäuelungen/g Gummi). Die Löslichkeitsparameter für gereinigten SBR aus Quellungs- und Viskositätsmessungen betragen 8.45 (kcal/ml)1/2 bzw. als Kohäsionsenergiedichte 71,403 kcal/ml. Mit diesem Wert des Löslichkeitsparameters wird der Lösungsmittel-Polymer-Wechselwirkungsparameter berechnet und durch die Methode von HUMMEL bestätigt. Der Durchschnittswert beträgt 0,37.
    Notes: The cross-linking efficiency of dicumyl peroxide with styrene-butadiene rubber (SBR-1507) has been measured by the swelling method. The values are found to be 2.5 and 5.0 for unpurified and purified SBR, respectively. The lower value in the former case has been ascribed to the destruction of peroxy radicals by the antioxidants present in the rubber. The physical cross-links due to chain entanglement for purified SBR are found to be 0.14 . 10-4 mole/g of rubber (0-07.10-4 cross-links due to chain entanglement/g of rubber). The solubility parameter for purified SBR as determined from both swelling and viscosity measurements is found to be 8.45 (kcal/ml)1/2 or cohesive energy density as 71.403 kcal/ml. Using this value of the solubility parameter, the solvent-polymer interaction parameter is calculated and is further verified by HUMMEL'S method. The average value is found to be 0.37.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 35 (1959), S. 292-295 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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