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  • 11
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 46 (1960), S. 3-17 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A viscometric polydispersity index may be calculated by forming the ratio of the viscosity-average molecular weights of a polymer in a relatively good solvent and in a relatively poor solvent and subtracting 1. This index has been examined by measuring dilute solution viscosities of a polydisperse polystyrene and a polydisperse methyl methacrylate in a variety of solvents, calculating viscosity-average molecular weights using Mark-Staudinger-Houwink equations, and forming the viscometric polydispersity indices. These are compared to Schulz parameters, weight-average-number-average molecular weight ratios minus 1, determined from osmotic pressure and light scattering. Viscometric polydispersity indices are more sensitive to polydispersities than expected when compared to Schulz parameters if account is taken of the differences in the powers of molecular weight in the various molecular weight sums. Viscometric polydispersity indices are examined for other polymers, including an almost monodisperse polystyrene. From these measurements it is concluded that the viscometric polydispersity index is valuable for characterizing the polydispersity of polydisperse linear polymers and rough fractions. The weight-average-viscosity-average polydispersity index is more sensitive than the viscometric polydispersity index and may be used to characterize relatively monodisperse linear polymers.
    Additional Material: 2 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 42 (1960), S. 383-390 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerization of the dichlorophosphinic nitride trimer, catalyzed by benzoic acid, ether, ethanol, or methanol, is first order in the trimer. With methanol and benzoic acid as catalysts, but not with ether, the first-order rate constants increase linearly with catalyst concentration. Solution polymerization in benzene is somewhat slower than bulk polymerization.
    Additional Material: 5 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 51 (1961), S. S14 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 57 (1962), S. 1-11 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The solvent power of a variety of diluents with polyvinyl chloride was evaluated in terms of the polymer - diluent interaction parameter χ and heat of mixing parameter B by means of a micromethod reported in the first part of this series. Among the diluents investigated are esters of phthalic, fumaric and maleic acids, alkyl-substituted benzenes, and condensed and conjugated aromatic ring systems. Relationships between solvency and diluent structure were sought in terms of the intermolecular forces involved in polymer - diluent associations. A condition found necessary for good solvency is that both the dispersion and dipolar forces acting between solvent molecules be similar in strength to the corresponding forces acting between polymer macromolecules. Steric hindrance of the carbonyl dipoles in the ester molecules, or of the aromatic nuclei in the hydrocarbon molecules, has a pronounced effect on the values of B. The extent of resonance interactions in the hydrocarbon molecules influence their solvent power. Where such interactions are reduced due to steric effects, solvency is also reduced.
    Additional Material: 2 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 57 (1962), S. 13-23 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The interactions between polyethylene and a number of hydrocarbon diluents were characterized on the basis of the Flory-Huggins interaction parameter χ and the closely related heat of mixing parameter B. The evaluations of these parameters were based on Flory's statistical-thermodynamic treatment of the effect of diluents on the melting points of crystalline polymers. Necessary for each evaluation was a single microscopic determination of the depressed melting point of polyethylene in its mixture with a given diluent as indicated by the disappearance of the last visible traces of crystallinity upon slow heating. Each mixture was diluted to an extent that the volume fraction of diluent approximated unity. This permitted the use of a simplified form of the Flory equation. The data obtained from the study of thirty diluents were utilized in an attempt to correlate diluent structure with solvency. Generally, the various types of hydrocarbon diluents can be rated in the following order of increasing solvency: aromatic, alkylaromatic, aliphatic, alicyclic. In addition, it was demonstrated that the value of B for a given diluent can be reliably estimated as a function of a new parameter which is calculated from the diluent structure, density, and an estimated value of the ionization energy. This new parameter also correlates well with the solubility parameter δT.
    Additional Material: 5 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 59 (1962), S. 357-378 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Oriented films of 4-O-methylglucuronoxylan from several sources were prepared by hot stretching acetyl derivatives. The resulting oriented samples could be converted to crystalline xylans without destroying the orientation. Infrared spectra of the oriented samples were recorded using polarized radiation. Band assignments were made on the basis of empirically known group frequencies, the spectra of the deuterated analogs (OH → OD), and comparison with the spectra of small molecule model compounds. The dichroic ratios observed for the carbon hydrogen modes in the polarized spectrum along with the observed 15 A. fiber repeat of crystalline xylan “hydrate” are interpreted in terms of a threefold screw polymer conformation. Finally, by comparison of the polarized spectrum of an oriented hardwood xylan with that derived from a radial section of hardwood it was deduced that the xylan is oriented in the fiber direction in the tree.
    Additional Material: 17 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 62 (1962), S. S62 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Tab.
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  • 18
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 62 (1962), S. 153-157 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of solvents on the molecular weight of polyacrylonitrile obtained by anionic polymerization with butyllithium was investigated. The molecular weight was found to decrease with increase in the dielectric constant of the solvents or their solvating power in the following order: petroleum ether « dimethylaniline 〉 diethyl ether 〉 tetrahydrofuran 〉 dimethylformamide. The termination step of the polymerization is by chain transfer to monomer. The rate of propagation increases with increase in the dielectric constant, and the decrease in molecular weight seems to be due to a greater increase in the rate of termination. This lowering in molecular weight in anionic polymerization with increase in the dielectric constant is contrary to what is generally known in cationic polymerization, where, due to termination by the gegenion, the molecular weight increases.
    Additional Material: 1 Tab.
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  • 19
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 62 (1962), S. S5 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 20
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 44 (1960), S. 549-551 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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