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  • 1975-1979  (3)
  • Polymer and Materials Science  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Experimenteller nachweis des molekulardispersen charakters der mischung von zwei polymeren und bestimmung des chemischen potentials in diesen mischungenHerrn Prof. Dr. G. V. Schulz zum 70. Geburtstag gewidmet (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 1145-1160 
    Details
    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: With the aid of small-angle neutron scattering the molecularly disperse character of a clear mixture of two polymers in the absence of a low molecular weight compound is proved in one case and disproved in the other. If the mixture is molecularly disperse the chemical potential and the coil dimensions can be determined. Poly(methyl methacrylate) and styrene-acrylonitrile copolymers for certain compositions of the copolymer form molecularly disperse mixtures. They are exothermic, have a negative excess entropy of mixing and the coils are expanded as compared with the unperturbed coil dimensions. The theory of solubility parameters of Hildebrand and Scott enables one to find the miscible system, but the experimental second osmotic virial coefficients differ by an order of magnitude from those which could be estimated from this theory.
    Notes: Mit Hilfe der Neutronenkleinwinkelstreuung wird der molekulardisperse Charakter einer glasklaren Mischung von zwei Polymeren bei Abwesenheit eines niedermolekularen Lösungsmittels in einem Fall nachgewiesen, im anderen widerlegt. Falls eine molekulardisperse Mischung vorliegt, können das chemische Potential und die Knäueldimensionen bestimmt werden. Polymethylmethacrylat und Styrol-Acrylnitril-Copolymere bilden für gewisse Zusammensetzungen des Copolymeren molekulardisperse Mischungen. Sie sind exotherm, besitzen eine negative Exzeßentropie und die Molekülknäuel sind gegenüber den ungestörten Knäueldimensionen expandiert. Die Theorie der Löslichkeitsparameter von Hildebrand und Scott ermöglichte zwar die Auffindung des mischbaren Systems, aber die gemessenen zweiten osmotischen Virialkoeffizienten sind in der Größenordnung verschieden von denen, die nach dieser Theorie vorausberechnet werden können.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770415
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Die bestimmung des chemischen potentials und des expansionskoeffizienten in mischungen von polydimethylsiloxanen unterschiedlichen molekulargewichtsHerrn Professor Dr. G. V. Schulz zum 70. Geburtstag gewidmet (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 1137-1143 
    Details
    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: If a polymer molecule is solved within a polymer melt of the same chemical nature but of different molecular weight, the solved polymer molecule in general is expanded as compared with the unperturbed statistical coil. The expansion coefficient and the second osmotic virial coefficient depend on the molecular weights of both polymers. The experimental results follow the lattice theory for athermic solutions of polymers.
    Notes: Wird ein Polymermolekül in einer Polymerschmelze von gleicher chemischer Art aber anderem Molekulargewicht gelöst, so ist das gelöste Polymermolekül im allgemeinen relativ zum ungestörten statistischen Knäuel expandiert. Der Expansionskoeffizient und der zweite osmotische Virialkoeffizient hängen von den Molekulargewichten der beiden Polymeren ab. Die experimentellen Befunde werden durch die Gittertheorie für athermische Lösungen von Polymeren richtig beschrieben.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770414
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Herstellung, charakterisierung und lösungseigenschaften von einheitlichen styrol-α-methylstyrol block-copolymeren (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 1793-1810 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An improved anionic polymerization technique for the preparation of highly uniform styrene/α-methylstyrene linear two-block copolymers is described. Three sets of samples with molecular weights M were prepared under equal experimental conditions, namely polystyrenes (2 · 105 〈 M 〈 3 · 106), poly(α-methylstyrene)s (7 · 104 〈 M 〈 4 · 106), and block copolymers (2 · 105 〈 M 〈 2,5 · 106). Ultracentrifugation in a density-gradient does not show any chemical heterogeneities in the block copolymers. The molecular polydispersity U = Mw/Mn-1 is U = 0,03 or less as estimated from GPC-measurements. The high molecular and chemical homogeneity of the block copolymers and the optical similarity of the two segment types yield light scattering measurements which give molecular weights Mw, radii of gyration 〈r2〉1/2 and second virial coefficients A2 with almost the same accuracy as in the case of homopolymers. The radii of gyration and the intrinsic viscosities of the block copolymers give no evidence for any “intramolecular phase separation” in the good solvent toluene. The coil conformation corresponds closely to that of the homopolymers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021780620
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    Paper (German National Licenses)
    Fulltext
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