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  • 1
    Electronic Resource
    Electronic Resource
    Cyanated liquid crystals with trans-stilbene structure: Syntheses and their cyclotrimerizations (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 313-321 
    Details
    ISSN: 0887-624X
    Keywords: liquid crystals ; cyanate ; cyclotrimerization ; liquid crystalline thermoset ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid crystalline aromatic monocyanate (M) and dicyanates (D1 and D2) with trans-stilbene (—Ph—CH=CH—Ph—) structure were synthesized and their cyclotrimerization reactions were studied by differential scanning calorimetry and infrared spectroscopy. Monocyanate M underwent cyclotrimerization to yield a trimerized material with discotic properties. Dicyanate D2 and its cured product failed to exhibit any mesophase. In contrast, polycyclotrimerization of dicyanate D1 obtained a liquid crystalline thermoset with its schlieren texture prolonged over a wide temperature range. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330213
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  • 2
    Electronic Resource
    Electronic Resource
    Cure kinetics of a flexible aromatic dicyanate with schiff base structure (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 1585-1592 
    Details
    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: Polycyclotrimerization of a flexible aromatic dicyanate with a Schiff base structure was studied by means of differential scanning calorimetry (DSC). The study on dynamic DSC evaluated an apparent activation energy (Ea) of 75.8 kJ/mol and autocatalytic first-order kinetics with rate expression Af(α) = 1.96 X 105 (1 + 4.39 α) (1 - α) min-1. The kinetic feature can be explained by a proposed mechanism consisting of hydroxyl-catalyzed and autocatalytic paths. The lower value of Ea compared with other aromatic dicyanates is due to the electron-withdrawing linkage of the inherent imine ( - CH=N) structure. The kinetic feature is affected by the content of the residual impurities (e.g., phenols or absorbed water) in the corresponding sample. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580922
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  • 3
    Electronic Resource
    Electronic Resource
    Modification of poly(acrylonitrile) via reaction with ti, zr, and hf dicyclopentadiene dichloridesPortions presented at the 162nd National American Chemical Society meeting in Washington, D. C. (1972)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 25 (1972), S. 121-129 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Modifizierung von Polyacrylnitril wurde durch Bildung von Polyacrylamidoxim und nachfolgende Kondensation mit Ti-, Zr- und Hf-Verbindungen durch Anwendung der Grenzflächentechnik erzielt.Die thermischen Eigenschaften dieser Produkte werden angegeben. Der anfänglich bei 200 bis 350 °C erfolgende Abbau verläuft wahrscheinlich über cyclische Produkte, während der Abbau oberhalb 500°C in Luft durch Oxydation des verbliebenen Produktes erfolgt.
    Notes: The modification of poly(acrylonitrile) was effected via formation of poly(acrylamideoxime) followed by condensation with Ti, Zr and Hf compounds. Modification was effected utilizing generally the interfacial technique.Thermal properties are reported. Initial degradation in the 200 to 350°C region probably occurs via the formation of cyclic products whereas at temperatures 〉500°C degradation in air occurs via oxidation of the remaining product.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1972.050250112
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of the motion of spin probes and spin labels in amorphous polymers with two-dimensional field-step ELDOR (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 1093-1104 
    Details
    ISSN: 0887-6266
    Keywords: EPR ; spin label ; spin probe ; spin relaxation ; correlation time distributions ; electron double resonance ; amorphous polymers ; side group liquid crystalline polymer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The motion of nitroxide spin probes and spin labels in amorphous polymers is studied below the glass transition temperature with a two-dimensional pulsed electron double-resonance experiment. Polystyrene and a liquid crystalline side group polymer are studied using both spin probes and spin labels covalently bound to specific sites along the polymer chain. Two methyl acrylic polymers differing only in their side group structure and polyvinylacetate are compared and large differences in the molecular dynamics deduced from both the nuclear and the electron spin relaxation rates are observed as the glass transition is approached. The results demonstrate the complexity of small amplitude motion in simple polymers below the glass transition temperature and show that it is very sensitive to the packing in the polymer. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Rate of sorption of organic vapors by films of cellulose acetatePresented before the High Polymer Forum at the 116th meeting of the American Chemical Society, Atlantic City, New Jersey, September 20, 1949. (1951)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 6 (1951), S. 457-469 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A detailed study has been made of the rate of take-up of vapors of methylene chloride and acetone by thin films of cellulose acetate (37.9% acetyl) as a function of vapor pressure, film thickness, and temperature. It was found that the method of film preparation and conditioning greatly influenced the kinetics of the take-up. Films, which were not completely dry, exhibit a much faster rate of take-up than dry films. Dry films could he obtained by either long treatment in a vacuum oven, or by water leaching followed by vacuum drying for five days. In either case, identical kinetic results are obtained. The mercury cast films used in this work give reproducible results and show a much slower rate of take-up than a comparable glass cast film.It was found that there was no fundamental difference in the rate of take-up for the vapors of methylene chloride and acetone, although in the liquid state the former is a limited swelling agent, while the latter is a solvent. For both these yapors there is a characteristic pressure above which several anomalies appear, which make a complete quantitative explanation of the data rather difficult. The most important of these anomalies is that, if one plots the amount of vapor taken up as a function of time, an inversion of slope is observed. This inversian is very marked and is a function of film thickness. Another anomaly that appears is that the absolute amount of vapor sorbed for thinner films is greater than that for thicker films for an appreciable time interval. The effect of temperature is complex. Above the pressures where the inversion of a slope occurs, the rate is lower a t higher temperatures for a considerable range of the sorption. These effects cannot be explained on the basis of a generalized diffusion equation with the boundary conditions which have been considered so far, i.e., assuming that the outer film surface is always in equilibrium with the vapor.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1951.120060406
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  • 6
    Electronic Resource
    Electronic Resource
    Diffusion of acetone into cellulose nitrate films and study of the accompanying orientationPresented before the Division of Physical and Inorganic Chemistry, meeting of American Chemical Society, Cleveland, Ohio, April, 1951. (1953)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 10 (1953), S. 241-252 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Studies have been made of sorption and desorption of acetone by films of cellulose nitrate (11 and 12% N) at 30°C. by following the weight of vapor takeup or loss as a function of time. The takeup-time curves show marked inflections and plots of takeup versus \documentclass{article}\pagestyle{empty}\begin{document}$\sqrt t$\end{document} are initially nonlinear for both sorption and desorption, indicating that Fick's law with the usual boundary conditions is not obeyed. The rate of vapor takeup is also considerably more rapid and different in character for films cast on glass than for films cast on mercury. A striking result is that for successive sorption-desorption cycles the rate of sorption decreases markedly, e.g., by a factor of 16 for five cycles. Studies of the optical anisotropy of the films show that the orientation of the polymer molecules normal to the plane of the film is increased by the diffusion process and it is concluded that this accounts for the decreased rate for successive sorption-desorption cycles and provides an explanation for the diffusion anomalies. A possible cause of this orientation is the observed anisotropic swelling combined with slow movement of the polymer segments.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1953.120100212
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  • 7
    Electronic Resource
    Electronic Resource
    Concentration gradients during sorption of vapor into polymers in the glassy stateWork sponsored by Office of Ordnance Research, U.S. Army. (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 21 (1956), S. 554-557 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.120219922
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  • 8
    Electronic Resource
    Electronic Resource
    Water induced acceleration of the diffusion of organic vapors in polymersPresented in part at the 123rd meeting of the American Chemical Society, Los Angeles, California, March, 1953. Work supported by a grant from Office of Ordnance Research, U.S. Army. (1954)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 14 (1954), S. 321-327 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of water vapor on the rate of diffusion of organic molecules has been studied at 40°C. by the sorption method for the systems water-acetone-polyvinyl acetate, water-carbon tetrachloride-polyvinyl acetate, water-acetone-cellulose acetate (37.9% acetyl) and water-benzene-polystyrene. For the first three systems the rate of diffusion of the organic vapor is markedly faster for the mixture of water and organic vapor than for the pure organic vapor. With polyvinyl acetate, the rate of diffusion of 80 mm. of acetone is increased about 25-fold if 36 mm. of water vapor is mixed with the acetone. Diffusion of the larger carbon tetrachloride molecule is accelerated by water even more than is acetone. Water vapor at a pressure of 36 mm. causes about a 30-fold increase in the rate of diffusion of 80 mm. of acetone into cellulose acetate even though the diffusion of acetone itself into cellulose acetate is anomalous. With polystyrene the presence of water vapor causes no acceleration of the diffusion of benzene which is the expected result since, in contrast to the other two polymers, polystyrene sorbs only very small amounts of water. It is concluded that the marked effect of water vapor on the diffusion of organic vapors into polyvinyl acetate and cellulose acetate involves (a) a rapid diffusion of water into the polymer and (b) more rapid diffusion of the organic vapor into the “water plasticized” polymer than into the dry polymer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1954.120147601
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  • 9
    Electronic Resource
    Electronic Resource
    Viscosity of dilute solutions of linear and branched polyvinyl acetateA preliminary account of this work was presented at the Ann Arbor High Polymer Research Conference, July 25, 1955. (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 22 (1956), S. 123-135 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dilute solution viscosity properties of fractions of two linear and one branched sample of polyvinyl acetate in benzene and of two linear and one branched fraction in several solvents were measured at 35°C. Values of total slope, b (from plots of ηsp/c vs. c), and intrinsic viscosities were obtained under the requirement that k′ + β = 0.500 ± 0.002. Empirical plots of log b vs. log [η] gave lines which were straight within the limits of accuracy of the data. For the linear fractions in benzene, Huggins' k′ was constant and the slope of the log b vs. log [η] line was 2; for the branched fractions in benzene, k′ increased with [η] and the slope of the log b vs. log [η] line was greater than 2. The log b vs. log [η] plots form the basis for a “one-point” method for determining [η]. Consideration of these data along with results reported in the literature indicates that k′ is measurably sensitive to branching only for fractions possessing a certain minimum combination of size and complexity. However, in some cases where the variations of k′ are inconclusive, use of the slope of the log b vs. log [η] line may provide a reliable indication of branching. It was found that a comparison between the branched and linear series could also be made at constant values of [η] or b. Two linear fractions in different solvents obeyed a type of Huggins relationship in which k′ did not vary with solvent and the slope of the log b vs. log [η] line was 2. For a higher molecular weight branched fraction, however, k′ varied from solvent to solvent and the slope of the log-log plot was about 1.7. These data do not support a reference point concept of “true” intrinsic viscosity based on a simple linear relationship between b and [η]. Preliminary results dealing with the effects of the shear rate indicated that the measured viscosity properties of branched fractions may be more seriously affected by changes in shear rate than those of linear fractions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.1202210014
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  • 10
    Electronic Resource
    Electronic Resource
    The concentration-dependent diffusion of styrene in ethyl cellulosePresented at the 138th Meeting of the American Chemical Society, New York, N. Y., September 11-16, 1960. (1962)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 56 (1962), S. 57-68 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The diffusion of styrene vapor in ethyl cellulose film has been studied as a function of styrene solubility in the film at 50°C. Methods and data are presented for determining the equilibrium solubility of styrene in ethyl cellulose as a function of vapor pressure at 50°C. The permeation rates of styrene vapor through 3-mil film were determined under steady state conditions for various pressures of pure styrene vapor on one side of the film and vacuum on the other side. From a plot of permeation rates versus styrene solubility the diffusion coefficient was calculated as a function of concentration. Measurements made over a concentration range of 0 to 0.7 g. styrene/cm.3 of unswollen film show that the diffusion coefficient first increases rapidly with concentration, then goes through a maximum, and finally levels off at 10-7 cm.2/sec. In the limited range of 0.06 to 0.10 g./cm.3 the diffusion coefficient varies exponentially with concentration as has been reported for other systems in a similar range. However, such a functionality does not represent the present system over a broad concentration range. These results, if generally applicable to other systems, indicate that the nature of the diffusion process for organic vapors in polymers may be considerably more complicated than formerly supposed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1962.1205616307
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