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  • 1
    Electronic Resource
    Electronic Resource
    Information on Polydispersity and Branching from Combined Quasi-Elastic and Intergrated Scattering (1980)
    s.l. : American Chemical Society
    Macromolecules 13 (1980), S. 1265-1272 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma60077a045
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of Hydrodynamic Preaveraging on Quasi-Elastic Scattering from Flexible Linear and Star-Branched Macromolecules (1980)
    s.l. : American Chemical Society
    Macromolecules 13 (1980), S. 580-587 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma60075a020
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Structural properties of fibrinogen and intermediate fibrins (1980)
    Springer
    European biophysics journal 6 (1980), S. 48-48 
    Details
    ISSN: 1432-1017
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00647521
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  • 4
    Electronic Resource
    Electronic Resource
    Pulse Induced Critical Scattering from solutions of randomly crosslinked polystyrene in cyclohexane (1982)
    Springer
    Polymer bulletin 7 (1982), S. 191-195 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The spinodal decomposition was observed by the Pulse Induced Critical Scattering technique for the three branched polystyrenes in cyclohexane. Branched polystyrenes were prepared by γ-irradiation on linear polystyrene of narrow molar-mass distribution for various periods. The location of the spinodals was hardly affected with regard to temperature though the crosslinking has increased the molar mass by a factor 10.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00255314
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamic light scattering from spherical particles (1983)
    Springer
    Colloid & polymer science 261 (1983), S. 635-644 
    Details
    ISSN: 1435-1536
    Keywords: Dynamic light scattering ; latex particles ; microgels ; hydrodynamic radius ; internal motions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The dynamic light scattering behavior of poly(butylmethacrylate) PBMA microgels and of kappa-casein micelles is compared with that from hard sphere latex particles. The latex particles and the kappa-casein micelles exhibited a single exponential decay of the time correlation function (TCF). For the microgels, progessively stronger deviations from a single exponential were observed as the scattering angle was made larger. These deviations are interpreted as being the result of internal modes of motion. From measurement of the first cumulant of the TCF, extrapolated towards zero angle, the translational diffusion coefficients D were determined, and the hydrodynamically effective radii were calculated via the Stokes-Einstein relationship. The ratio of the radius of gyration to the hydrodynamic radius was found to beϱ=0.775+0.012 for the latex particles, in good agreement with theory. The microgels, however, exhibit much lowerϱ-parameters of 0.49 to 0.58, while the kappa-casein micelles showed the opposite behavior with values between 1.1 and 2.5. The results are interpreted on the basis of the DebyeBueche and Deutsch-Felderhof theory for porous spheres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415033
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  • 6
    Electronic Resource
    Electronic Resource
    Quasi-elastic light scattering from polymethylmethacrylate in a good and a theta solvent (1980)
    Springer
    Colloid & polymer science 258 (1980), S. 675-684 
    Details
    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 translatorische Diffusionskoeffizienten von 9 verschiedenen PMMA Proben wurden in Aceton bei 20 °C und in Butylchlorid bei 34.5 °C (Thetatemperatur)|durch quasielastische Lichtstreuung bestimmt. Die durch das ausgeschlossene Volumen verursachte Knäuelexpansion wurde durch einen Expansionsfaktor ah des hydrodynamischen RadiusR h beschrieben. α h erreicht beiM w →M o (MonomerMolekulargewicht) Werte deutlich unterhalb von 1.0. Aus der Cowie-Bywater Auftragung wurden andererseits keine unterschiedlichen ungestörten Dimensionen in den beiden Lösungsmitteln erhalten. Hieraus wird der Schluß gezogen, daß α h 〈 1.0 eine Folge unterschiedlicher hydrodynamischer Radien der Segmente ist. Das VerhältnisS/R =S 2〉 1/2/R h erwies sich nach den Messungen kleiner als die Theorie erwarten ließ. Mögliche Gründe für dieses Verhalten werden diskutiert. Die Konzentrationsabhängigkeit der Diffusionskoeffizienten wurde anhand der Theorie vonPyun undFixman ausgewertet. Es wurde eine zufriedenstellende Übereinstimmung mit den von den Autoren verwendeten einfachen Modellen der harten bzw. weichen Kugel in dem guten bzw. schlechten Lösungsmittel gefunden.
    Notes: Summary Translational diffusion coefficients of 9 PMMA samples have been measured by quasi-elastic light scattering in acetone at 20 °C and butylchloride at 34.5 °C (theta solvent). The coil expansion due to excluded volume effects has been characterized by the expansion factor α h of the hydrodynamic radiusR h . αh has been found to reach avalue well below 1.0 atM w →M o (the monomer). By means of CowieBywater plots on the other hand the unperturbed chain dimensions are shown being virtually identical in both solvents. Thus, the α h 〈 1.0 values is the result of differences in the hydrodynamic radii of the segments in the two solvents. The ratioS/R =S 2 =1/2/R b is found being lower than predicted by theory. Reasons for this behaviour are discussed. The concentration dependence ofD has been evaluated on the basis of a theory by Pyun and Fixman. A reasonably good agreement with the simple models of a hard and a soft sphere in a good and a poor solvent, respectively, is observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01384359
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  • 7
    Electronic Resource
    Electronic Resource
    Untersuchungen zum Einfluß von Topographie und Korngröße von Pulvern bei der energiedispersiven Elektronenstrahlmikroanalyse (1981)
    Springer
    Microchimica acta 76 (1981), S. 483-498 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary In the present contribution, the action of the application of powder on the energy-dispersive X-ray microanalysis was investigated. Of the systems MgO-Al2O3 and SiO2-MnO, both powder preparations and powders pressed to tablets were prepared with various granule sizes. For comparison, microsections of melted mixed crystals and fluxes were used. Compared with smooth surfaces, the topography of scattered powders only leads to a greater range of variation of the results necessitating a very much larger number of surface analysis to attain the same accuracy. Preparations which consist of two powders with different granule sizes lead to a disproportionate yield for the elements of the finer powder. This is caused by fulling of the spaces between the larger granules by the finer powder at the surface of the sample. In addition, an envelopment of the coarse particles by the finer particles contributes to intensification of this effect. With the same granule size of both powders, the absolute size of the particles does not influence the yield conditions. To attain a smaller variation, small granule sizes of the powder are desirable. Tablets from ground mixtures of the powder show only slightly greater analysis errors than mixed crystals and fluxes, and indeed as a rule a smaller standard deviation due to the good homogenization.
    Notes: Zusammenfassung Im vorliegenden Beitrag wurde untersucht, welche Auswirkung die Anwendung von Pulvern auf die energiedispersive Röntgenmikroanalyse hat. Von den Systemen MgO-Al2O3 und SiO2-MnO wurden sowohl aufgestreute als auch zu Tabletten verpreßte Pulverpräparate mit verschiedenen Korngrößen hergestellt. Zum Vergleich wurden Schliffe aufgeschmolzener Mischkristalle und Aufschlüsse benutzt. Die Topographie aufgestreuter Pulver führt im Vergleich mit glatten Oberflächen nur zu einer größeren Streuung der Ergebnisse, die zur Erzielung gleicher Genauigkeit wie bei diesen eine wesentlich größere Zahl von Flächenanalysen erfordert. Präparate, die aus zwei Pulvern mit unterschiedlicher Korngröße zusammengesetzt sind, führen zu einer verstärkten Ausbeute für die Elemente des feineren Pulvers. Dies wird durch Auffüllung der Zwischenräume zwischen den größeren Körnern an der Oberfläche der Probe durch das feinere Pulver verursacht. Außerdem trägt eine Umhüllung der groben durch die feineren Partikel zur Verstärkung dieses Effektes bei. Bei gleicher Korngröße beider Pulver hat die absolute Größe der Partikel keinen Einfluß auf die Ausbeutenverhältnisse. Zur Erzielung einer geringen Streuung sind kleine Korngrößen der Pulver wünschenswert. Tabletten aus aufgemahlenen Mischungen der Pulver zeigen nur unwesentlich größere Analysenfehler als Mischkristalle und Aufschlüsse, in der Regel sogar durch die gute Homogenisierung eine geringere Standardabweichung.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01196966
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