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  • 1
    ISSN: 1573-8922
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Conclusion 1. It has been established that, as the chain of polyphenylquinoxalines becomes more rigid by addition of aromatic nuclei of the naphthylimide group to the macromolecule part, the wear resistance of graphite-filled polymer systems increases. 2. It has been demonstrated that during friction with filled polyphenylquinoxalines in the polymer binder there occur complex destructive-structurizing processes whose penetration depth is determined by the chemical constitution of the selected polymers. 3. It has been established that in the rigid-chain polyphenylquinoxaline during friction at high temperatures, just below the glass-transition point but within the range of faster relaxation processes, the destructive-structurizing processes abate and then at temperatures above 250°C active gelling occurs.
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  • 2
    ISSN: 1573-8922
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Conclusions 1. The process of friction of antifrictional self-lubricating plastics based on F-1 polyarylate and various fillers has been studied. It has been shown that a distinctive feature of this process is the formation of a film of the same composition as that of the antifrictional plastic on the steel surface. 2. It has been shown that during the process of friction of antifrictional self-lubricating plastics both structural changes in the mobybdenum disulfide and also tribochemical transformations of molybdenum disulfide and copper, plus reaction of these with the counterbody material, take place in the surface films. 3. It has been found that the nature of the tribochemical transformations depends on the chemical composition of the antifrictional self-lubricating plastic and affects the temperature limits of the friction zones.
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  • 3
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyalkane imides based on 3,3′,4,4′-diphenyloxidetetracarboxylic, pyromellitic and 1,4,5,8-naphthalenetetracaboxylic acids, and aliphatic diamines containing 4, 6, 8, 10, or 12 methylene groups have been studied. Relations governing the effect of structure on solubility, heat resistance, density, and crystallizability have been established. Conformation analysis has been carried out and models of the macromolecules have been constructed. The morphology of the crystalline polymers has been studied. For the polymers of the given class, crystallization capability is shown to be associated with the conformational flexibility of the macromolecular unit determining a given acid moiety by the number of methylene groups in the diamine unit.
    Additional Material: 10 Ill.
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  • 4
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Scattering by extruded polyethylene films has been used to analyze in detail the small-angle scattering of x-rays by strained spherulitic samples. It is shown that the basic small-angle patterns in spherulitic specimens can be obtained by summing small-angle reflections from films drawn both parallel and normal to the direction of extrusion. The representation of a complex pattern by superposition of simpler reflection makes it possible to calculate local strains in various regions of spherulites in bulk specimens.
    Additional Material: 9 Ill.
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  • 5
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of crystallization and structure formation of polycaproamide (PCA) during anionic adiabatic polymerization of ε-caprolactam was studied. The adiabatic crystallization was shown to comprise three successive stages. In the first stage PCA forms dendritelike structures, the space between which is filled with the monomer. In the second stage rather rapid crystallization proceeds to give large loose spherulites. The dendritic structures serve as nuclei for development of spherulites. In the third stage slow secondary crystallization occurs. It is accomplished by crystallization of the residual amorphous substance located both in the dendritic nucleus and throughout the volume of the spherulites. This process is followed by the partial disappearance of the dendritic nuclei and by thickening of lamellae, which results in a substantial densification of initial structures and appearance of fine spherulites. As a result, a fine spherulitic structure with 50% crystallinity is formed.
    Additional Material: 6 Ill.
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  • 6
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. Crystalline complexes of the phenylacetylide of copper and triphenylphosphine with Cu-to-P ratios of 1∶1 and 2∶3 have been prepared and characterized. 2. The 1∶1 complex has been shown to exist in two isomeric forms.
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  • 7
    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
    Description / Table of Contents: Zusammenfassung Die Röntgen-Beugung eines Systems aus linearen Kristalliten wurde berechnet, um verschiedene Formen von Kleinwinkelreflexionen zu erklären. Die Berechnungen zeigen, daß die beobachteten verschiedenen SAX-Beugungsbilder theoretisch erhalten werden können, wenn die Form der verschiedenen Kristallite in geeigneter Weise gewählt wird. Verschiedene Beugung kann im wesentlichen mit Änderungen von Kristallitgestalt und -große gedeutet werden. Strich-, 2-Punkt- und 4-Punkt-Beugung sind mit rechteckigen und plättchenförmigen Kristalliten von kleinen lateralen Dimensionen verknüpft. Im Fall von radialen Reflektionen ist der einzelne Kristallit ein Plättchen, und eine Fibrille ist ein Stapel von Plättchen. Strukturänderungen in orientierten Proben mit planarer Kristallittextur, erzeugt durch Schrumpfung, wurden studiert. Der Hauptvorgang bei Schrumpfung besteht im Wachsen der lateralen (mit Hinblick auf die Texturachse) Kristallit-dimensionen und in ihrer Überführung in Plättchen. Gleichzeitig findet eine Drehung der Achsen der Makromoleküle statt. Im 2. Stadium der Schrumpfung schrauben sich die Schichten um eine Achse senkrecht zur Filmebene. Dann bildet sich die isotrope Struktur. Der Übergang zwischen den beiden Arten von Beugungen ist für die verschiedenen Prozesse typisch, die im Laufe einer Deformation und einer Schrumpfung von Polymeren stattfinden.
    Notes: Summary Diffraction by a linear crystallite system was calculated to explain different shapes of small-angle reflections. The calculations show that various SAXS patterns observed can be obtained theoretically if the shape of certain crystallites are accounted for. Various reflection shapes can be explained chiefly by the changes in the crystallite shape and size. Dash, four-point and two-point reflections are associated with rectangular and oblique crystallite of small lateral dimensions. In the case of radial reflections the crystallite represents a plate and the fibril — a stack of plates. Structural changes in oriented samples with planar crystallite texture caused by shrinkage were studied. The principal process of shrinkage consists in the growth of lateral (with respect to the texture axis) crystallite dimensions and in their transformation into plates. Simultaneously the rotation of the macromolecule axis takes place. At the second stage of the shrinkage the layers twist around an axis perpendicular to the film plane. Then isotropic structure is formed. Transition between the two kinds of reflections are typical of various processes taking place in the course of polymer deformation and shrinkage.
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