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  • 1
    Electronic Resource
    Electronic Resource
    Temperature dependence of copolymerization parameters in ethene/1-octene copolymerization using homogeneous rac-Me2Si(2-MeBenz[e]Ind)2ZrCl2/MAO catalyst (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 735-740 
    Details
    ISSN: 0887-624X
    Keywords: homogeneous Ziegler-Natta polymerization ; metallocenes ; ethene/1-octene copolymerization ; copolymerization parameters ; influence of the temperature and solvent ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethene was copolymerized with 1-octene using homogeneous MAO-activated rac-Me2Si(2-MeBenz[e]Ind)2ZrCl2 at constant ethene concentration with temperature varying between 0 and 60°C to determine a temperature dependence of copolymerization parameters. At constant 1-octene and ethene concentration (constant ethene/1-octene feed molar ratio) 1-octene incorporation decreased with increasing temperature. Furthermore, when ethene/1-octene molar ratio was varied by varying the temperature keeping 1-octene concentration and ethene pressure constant, increasing temperature accounted for lower molecular masses without affecting 1-octene incorporation. An explanation for the observed temperature dependence of the copolymerization parameters is presented, considering the solution-enthalpy of the gaseous ethene in the solvent. In all cases amorphous poly(ethene-co-1-octene) with 1-octene content varying between 20 and 40 mol % was obtained. © 1997 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Estimation of sphere-size distributions in two-phase polymeric materials from transmission electron microscopy data (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 39-50 
    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: The blending of two immiscible polymer samples can lead to spherical inclusions of one component in a matrix of the other component. The mechanical solid-state properties as well as the flow behavior of the m+lt depend on the size of the spheres in the blend. For that reason, the sphere-size distribution is of major interest. Information about this distribution is often obtained by analyzing thin slices of the blend with transmission electron microscopy. In that way, however, the sphere-size distribution itself is not obtained. The reconstruction of the sphere-size distribution is introduced as a stereological problem, well known in fields as metallurgy, biology, geology, and medicine. It is shown that the sphere-size distribution can be reconstructed using a regularization method as implemented in the program FTIKREG. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070530105
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Transverse NMR relaxation of water in wood (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 3147-3154 
    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: The transverse NMR relaxation times of hydrogen nuclei of water absorbed in white spruce sapwood [Picea glauca (Meunch) Voss] were measured for moisture contents in the range from 5 to 176%. The spin echo amplitudes resulting from the Carr-Purcell sequence decay nonexponentially suggesting the possibility of at least two different relaxation times for water in wood. A simplified structural model of the wood-water mixture is used to estimate the rates of chemical exchange at room temperature of hydrogen nuclei between various sites in the system. The high-resolution NMR line shape is discussed briefly in terms of this proposed model.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070231101
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  • 4
    Electronic Resource
    Electronic Resource
    Computerunterstützte akustische Auslegung verfahrenstechnischer Anlagen (1992)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 64 (1992), S. 783-783 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330640926
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  • 5
    Electronic Resource
    Electronic Resource
    Model of partial crystallization and melting derived from small-angle X-ray scattering and electron microscopic studies on low-density polyethylene (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 1361-1381 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A temperature-dependent small-angle x-ray scattering and electron microscopic study on a sample of low-density polyethylene affords a determination of the structure changes in a heating and cooling cycle and suggests a new model of partial crystallization and melting. The analysis of SAXS data is based upon some general properties of the electron-density correlation function. Electron micrographs are obtained from stained sections γ irradiated at elevated temperatures and are analyzed quantitatively by statistical means. According to the model proposed here the thickness distribution in the amorphous layers, rather than that of the crystalline regions, is the essential factor governing the crystallization and melting behavior. The temperature-dependent changes in this thickness distribution provide a natural explanation for the large reversible changes in long-spacing.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180180615
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  • 6
    Electronic Resource
    Electronic Resource
    Direct evaluation of the electron density correlation function of partially crystalline polymers (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 1343-1359 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A discussion of the general properties of the one-dimensional electron density correlation function K(z) of a partially crystalline polymer with lamellar structure shows that application of a graphical extrapolation procedure permits direct determination of the crystallinity, the specific inner surface, and the electron density difference ηc - ηa. The procedure is based upon the occurrence of a straight section in the “self-correlation” range of K(z). Curved and nonparallel lamellae do not invalidate the concept. In the case of heterogeneous samples composed of partially crystalline and totally amorphous regions, some of the parameters of the experimentally obtained correlation function, as for example the invariant K(0), are affected and may lose their definiteness. Use of the method is demonstrated in a detailed discussion of the correlation functions measured for a sample of lowdensity polyethylene at 25 and 100°C.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180180614
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