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  • Polymer and Materials Science  (80)
  • 550 - Earth sciences
  • Chemical Engineering
  • 1950-1954  (80)
  • 1
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The study of the rate of polymerization per particle in emulsion systems has been extended to include the following monomers and initiator systems: TextMonomerInitiator SystemStyrenePersulfateStyreneCHP-TETAIsopreneDIBHP-TEPAIn all cases, linear rates of polymerization were obtained in the region where the number of particles can be considered as remaining constant (30-60% conversion). Furthermore, the addition of catalyst in this region did not affect the rate of polymerization, so that a rate per particle could be calculated. From the rates per particle, the following absolute propagation rates were calculated for styrene and isoprene, and are compared with values obtained for styrene from photoinitiation studies: TextMonomerCatalyst systemEact.Akp at 60°C.StyrenePersulfate7.44.1 × 107277StyreneCHP-TETA8.43.3 × 107221StyrenePhotoinitiation7.82.2 × 107176IsopreneDIBHP-TEPA9.81.2 × 10850
    Additional Material: 3 Ill.
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  • 2
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been carried out on the emulsion polymerization of butadiene, using the “peroxamine” recipe at low temperatures in an attempt to evaluate the absolute propagation rate, according to the theory of Smith and Ewart, from a determination of the rate of polymerization per particle of latex. Unlike the persulfate-mercaptan system previously reported, the hydroperoxide-polyamine systems show a polymerization rate per particle which is independent of all variables other than temperature. Hence this system behaves according to case 2 of the Smith-Ewart treatment, where the number of free radicals per particle is approximately 1/2. On this basis it is possible to calculate a value for the absolute propagation rate constant for butadiene, as follows: kp = 1.2 × 108 e-9300/RT l./mole/sec. This value in turn leads to an evaluation of the absolute rates of some other reactions involving the butadiene radical, such as cross-linking, chain transfer, and copolymerization. It agrees with the current data on absolute rates for other monomers and with present-day theories concerning the effect of conjugation on radical-monomer interaction.
    Additional Material: 4 Ill.
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  • 3
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The small angle scattering of ramie and of 25 highly oriented rayon samples of widely different prehistory has been examined in both the air-dry and the water-swollen condition with monochromatic radiation in a vacuum camera. All intensity curves are given. For some rayons the curves show distinct maxima or inflection points in either the swollen or the dry condition which seem to be indicative of the existence of a maximum of relatively low intensity superimposed on a normally descending small angle intensity curve. The Bragg spacing corresponding to these maxima lies close to 80 A. for the swollen and to 50 A. for the dry fibers. Other specimens either do not show these superimposed maxima or show only faint indications of their occurrence. The existence of maxima (particularly pronounced in Fortisan, Fiber G, Super Cordura, and Celanese K 36) seems to demonstrate that in some rayons a part of the fiber substance has a micellar structure of unexpectedly high regularity and with average interparticle distances given by the Bragg spacings indicated. The intensity curves of those swollen specimens which did not exhibit a maximum, when evaluated by the Guinier method for dilute systems, assuming parallel cylinders as the basic structure, yield figures between 35-55 A. for the diameter of the cylinders. Evaluation of the intensity curves according to an approximation suggested by Kratky (based on the picture of closely packed lamellae) points to the existence of a preferred spacing of the same order of magnitude (∼40 A.) for the dry and of ∼60 A. for the swollen fibers. No clear correlation between small angle scattering features and other known properties of the rayons has been detected.
    Additional Material: 7 Ill.
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  • 4
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been carried out on the emulsion polymerization of butadiene, using the Mutual Recipe, in an attempt to evaluate the absolute propagation rate, according to the theory of Smith and Ewart, from a determination of the rate of polymerization per particle of latex. It was found, as expected, that the number of particles formed is a function of the temperature of initiation, almost doubling in number for a 10°C. rise in temperature. This number is also a function of the soap charge, being approximately proportional to the square root of the soap concentration. Unlike the case of styrene polymerization, the rate of polymerization per particle was found to be affected by the amount of soap adsorbed on the particle, hence it cannot be considered as representing the true propagation rate for butadiene. However, the rate of polymerization, when calculated per mole of soap present, was found to be a function of temperature only, yielding an activation energy value of ca. 14 kcal.
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 5 (1954), S. 178-182 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 5 (1954), S. 241-243 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: On the Building-up of the Double Layer on Iron and Lead Electrodes in SoilsThe building-up of the double layer on Iron and Lead electrodes was followed by means of the Hickling method. The results obtained from the present series of experiments were in agreement with results obtained from previous experiments on the corrosion of Iron and Lead when buried in soils. This applied particularly to the type of corrosion obtained when the water content of the soil was below the saturation point. Only the first part of the Helmholtz double layer was formed on an Iron elctrode buried in a sandy soil of low water content. When the saturation point was exceeded, the building-up took place in exactly the same manner as in distilled water. A Lead elctrode buried in a clay soil was found to have a double layer similar to that obtained when the electode is immersed in electrolytes. In this case the capacity of the differents parts of the double layer is greater than that of the Helmholtz double layer.
    Notes: Der Aufbau der Doppelschicht an der Fe- und Pb-Elektrode wurde mit Hilfe der Hicklingschen Methode verfolgt. Im Einklang mit den Ergebnissen, die bei früheren Korrosionsversuchen mit Eisen und Blei im Erdreich erhalten wurden, ergab sich bei den Untersuchungen, die völlige übereinstimmung bezüglich der Entstehung der Korrosionstype, wenn sich der Boden hinsichtlich seines Wassergehaltes unter seiner Sättigungsgrenze befindet. Auf einer Fe-Elektrode bildet sich in sandhaltigem Boden bei niedrigen Wassergehalten nur der erste Teil der Helmholtz-Doppelschicht aus, nach Überschreiten der Sättigungsgrenze weist diese die gleiche Ausbildung auf wie in destilliertem Wasser. Eine Pb-Elektrode weist dagegen in tonhaltigem Boden eine Doppelschicht auf, die der ähnelt, die sich in einem Elektrolyt ausbildet. In diesem Fall ist die Kapazität des diffusen Teils der Doppelschicht größer als die der Helmholtz-Doppelschicht.
    Additional Material: 12 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 2 (1951), S. 9-14 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Aufgabe und Bedeutung der Zahnradgetriebe im chemischen Apparatebau  -  Ausführungsformen, deren Vorteile und Anwendungsbereich (Schneckengetriebe, Stirnradgetriebe, Kegelgetriebe und stufenlose Flüssigkeitsgetriebe).
    Additional Material: 12 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 5 (1950), S. 375-375 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 5 (1950), S. 565-568 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 5 (1950), S. 615-632 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
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