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  • Polymer and Materials Science  (2)
  • D63
  • 1960-1964  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 8 (1964), S. 119-140 
    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: The standardization of notched Izod impact test data to normalized values of foot pounds per inch of notch is based on the assumption of a 1:1 increase in breaking strength with increasing notch width. This assumed relation is not supported by experimental tests on commercial thermoplastics. As notch width was increased from 1/8 to 1/4 to 3/8 to 1/2 in., nine of ten thermoplastics tested showed a decrease in normalized impact strength. Each material appears to show a characteristic loss in breaking strengths as the notch width increases. A technique developed for calibration of pendulum impact testers has been used to examine the variation of impact breaking strength in relation to the total kinetic energy of the hammer. Experimental tests show practically no change in impact strengths up to values that take 2/3 of the available hammer energy. Experimental work on the comparison of the impulse transferred by the hammer during breaking with impulse curves photographed by the Autographic Impact test show very good agreement for catastrophic breaks and fair agreement for plastic type breaks. The reduction in recorded impulse is attributed to the degrading of the sample during the plastic portion of the breaking cycle. The peak force of thermoplastics as measured by the Autographic Impact test increases as the temperature decreases from 100°C. or above to 0°C. Over the same temperature range flexural tests on small cantilever samples of these thermoplastics show the same thermal dependence for the flexural yield or permanent distortion stress. Plots of the impact peak forces and flexural yield stress at corresponding temperatures give a linear correlation. Each thermoplastic material exhibits a unique relation for this correlation between impact yielding and flexural yielding. This correlation between the impact and flexural tests over the range of temperatures is the first known experimental indication of a direct relation between impact properties and standard physical tests.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 2
    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: Der Einfluß der sterischen Anordnung der Epoxydgruppe auf den Härtungsverlauf und auf andere Eigenschaften von Epoxydharzen, die 3-Oxatricyclo[3,2,1,02,4]oct-(6)-yl- oder 4-Oxatetracyclo [6,2,1,02,7,03,5]undec-(9 oder 10)-yl-reste enthalten, wurde untersucht. Die Gasbildung, die während der Härtung gewisser Verbindungen der erstgenannten Klasse mit Anhydriden beobachtet wurde, ist durch eine intramolekulare Reaktion der Epoxydgruppe mit der Brückengruppe zwischen den cyclischen Resten erklärbar. Die Epoxydierung der Tricyclo[5,2,1,02,6]undec-(3)-en-(8 oder 9)-yl-Derivate ist durch eine starke Stereoselektivität gekennzeichnet, und die beiden möglichen sterischen Isomertypen wurden einerseits durch Epoxydierung mit Peressigsäure und andererseits durch Bildung der Chlorohydrin-Acetate und ihre Verseifung und Dehydrochlorierung erhalten. Die relative Reaktivität der beiden stereo-isomeren Reihen wurde untersucht. Das Chlorhydrinverfahren läßt sich wegen der dabei auftretenden Umlagerungsreaktionen nicht für die Epoxydierung von Bicyclo[2,2,1]hept-(5)-en-(2)-yl-derivaten anwenden.Bei Epoxydharzen, die auf der Basis des Cyclohexanrings aufgebaut sind, wurden keine analogen stereochemischen Erscheinungen beobachtet.
    Notes: The effects of the steric environment of the epoxy group on the curing and other properties of epoxy resins containing 3-oxatricyclo [3,2,1,02,4]oct-6-yl and 4-oxatetracyclo[6,2,1,02,7,03,5]undec-9(or 10)-yl residues were examined. During the anhydride cure of certain members of the former class, evolution gas was observed. This is attributed to intramolecular reaction between the epoxide group and the linkage between the two ring systems. Stereoselectivity in epoxidation of tricyclo[5,2,1,02,6]undec-3-en-8(or 9)-yl derivatives is high, and the two possible series of stereoisomers were obtained, by epoxidation with peracetic acid and by formation and saponification-dehydrochlorination of chlorohydrin-acetates, respectively. The relative reactivities of the two stereoisomeric series were examined. The route via the chlorohydrin is not applicable to epoxidation of dehydronorbornyl derivatives, owing to the occurrence of rearrangements.No analogous stereochemical effects were observed with cyclohexane-based epoxy resins.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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