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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of meningococcal polysaccharides by optical mixing spectroscopy. II. Effects of temperature, EDTA, and ionic strength on aggregation of group C polysaccharides in solutionWork supported by FDA. (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 945-963 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied the effects of temperature, EDTA, and ionic strength on C-polysaccharides in solution by examining the details of the time-correlation function using a 96-channel single-clipped photon correlation spectrometer. Our linewidth results have shown that the C-polysaccharides in buffer solution form aggregates of very broad distributions. Thus, fractionation by gel-filtration chromatography is only mildly effective. Although the aggregate sizes seem to remain relatively constant from 4 to 25°C, a fraction of those aggregates break up to form smaller fragments or monomers at higher temperatures. However, the dissolution-association process is quite slow and takes days even at room temperatures before the equilibrium is reached. We have also shown that by adding an excess amoutn of EDTA, the aggregates can be broken up. Again the dramatic changes occur only at short delay times suggesting that a protion of the larger aggregates remains. Finally, the amount and size of aggregates depend upon the ionic strength which exhibit a maximum ΓT/sin2 (θ/2) around 0.1-0.2 M KCl.If the activities of polysaccharides in solution depend upon molecular size, the standard techniques such as gel-permeation chromatography and ultracentrifugation cannot properly characterize the detailed size distribution. Quasielastic laser light scattering can provide us with a qualitative model. The quantitative details must necessarily await more extensive investigations using a combination of the techniques and better fractionation procedures in an appropriate buffer solution.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160502
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of entrance geometry on the capillary flow of cellulose acetate-acetone solution (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 2175-2184 
    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: Capillary flow data were obtained for a 27.5% solution of cellulose acetate in acetone. The solution temperature was 50°C, and the range of apparent shear rates investigated was 1.7 × 105 to 1.7 × 106 sec-1. Capillaries having tapered entrance angles of 37.88° to 120.63° were used. A power-law model was adequate to describe the shear stress at the wall (τw) and the corrected shear rate \documentclass{article}\pagestyle{empty}\begin{document}$(\dot \gamma )$\end{document} relationship. Entrance angle affected the entrance pressure drop corrected for kinetic energy, (ΔP0,c); ΔP0,c increased as the angle widened. Treating the entrance flow as an elongational flow situation facilitated superposition of the Delta;P0,c data on a single curve. Estimated elongational viscosities decreased with increasing applied stress.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160902
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  • 3
    Electronic Resource
    Electronic Resource
    Measurement of diffusion coefficients of meningococcal polysaccharide by optical mixing spectroscopy. I. A preliminary characterization on the aggregation of the Group C polysaccharide (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 2281-2292 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The angular distribution of scattered intensity and decay times of concentration fluctuations have been measured by means of digital photon counting and single-clipped photon correlation for solutions of Group C meningococcal polysaccharides at 31°C. The z-average diffusion coefficient 〈D〉z and its second moment 〈D2〉z have been determined from the time-dependent correlation function using the cumulant expansion technique. Very low observed values of 〈D〉z and the tremendous width of the polydispersity index, which is the z-average normalized variance, suggest a higher degree of aggregation than the monomer-dimer type self-association at finite concentrations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360131110
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  • 4
    Electronic Resource
    Electronic Resource
    Self-association of β-lactoglobulin A in acid solution. I. Translational diffusion coefficients (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 93-109 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report measurements of the diffusion coefficient of β-lactoglobulin A (βLG-A) at pH = 5.60 and 4.58 in 0.10 ionic strength acetate buffer by the techniques of analog photocurrent signal correlation and digital single-clipped photon correlation. At a concentration of 21 mg/ml and a pH of 4.58, the self-association of β-lactoglobulin can be represented by a simple dimer-octamer equilibrium model. We determined the translational diffusion coefficient of the dimer and that of the octamer using the scattering results of Kumosinski and Timasheff in a dimer-octamer mixture. Our analysis shows that the dimer βLG-A does not change its size if the pH is varied from 5.60 to 4.58 and both species remain constant in size for temperature changes from 3.5° to 25°C Hydrodynamically, the octamers behave like closed-packed spheres with an effective radius of about 45 Å according to the Stokes-Einstein relation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140108
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal diffusivity and conductivity of crystalline polymers (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 2325-2335 
    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 thermal diffusivity and conductivity of the isotropic and drawn samples of five semicrystalline polymers - nylon 6, poly(ethylene terephthalate), poly(butylene terephthalate), polybutene-1, and poly(4-methylpentene-1) - were measured by the flash method over the temperature range 100-350 K. The temperature dependence of the thermal diffusivity was found to follow a simple phenomenological pattern, while a more detailed understanding of the temperature dependence and the effect of orientation on thermal conductivity was obtained by using the modified Maxwell model.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260719
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  • 6
    Electronic Resource
    Electronic Resource
    Negative thermal expansion of polymer crystals: Lattice model (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 2313-2322 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The lateral thermal motion of atoms in an inextensible polymer chain would cause a shortening along the chain direction. This effect could explain the observed negative thermal expansivity α along the chain direction of a polymer crystal. Using this idea, the expansivity α is calculated for a lattice of parallel linear chains. A value of -1.3 × 10-5 K is obtained for chains with a carbon backbone, in good agreement with data for polyethylene.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180181201
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  • 7
    Electronic Resource
    Electronic Resource
    Thermal conductivity of oriented crystalline polymers (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 1187-1207 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal conductivities of six oriented semicrystalline polymers which range from 0.37 to 0.63 in crystallinity and 1 to 5 in draw ratio λ (up to about 15 for two polymers) have been measured between 100 and 340 K. It was found that for increasing λ the conductivity K∥ (along the draw direction n̂) increases rapidly while K⊥ (normal to n̂) decreases slightly; K∥ also increases with temperature, but K⊥ shows no simple pattern in temperature dependence. These general features can be reproduced reasonably well at low draw ratio (λ 〈 5) by the modified Maxwell model, and the discrepancy in details may be attributed to the fact that the model does not take into account the possible anisotropy of the amorphous phase of the oriented polymers. At high draw ratio the intercrystalline bridge effect becomes important, and one must resort to the Takayanagi model, but the lack of corroborating x-ray data has rendered a detailed comparison impossible.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180180603
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  • 8
    Electronic Resource
    Electronic Resource
    Negative thermal expansion in oriented crystalline polymers (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 335-352 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements on the thermal expansivity α∥ and α⊥ (along and normal to the draw direction, respectively) have been carried out for a series of oriented polymers with widely different crystallinities (0.36-0.81) and draw ratios (1-20) and over large temperature ranges covering the major amorphous transitions in each case. While α⊥ increases with temperature, α∥ tends to decrease sharply above the transition temperature. For highly crystalline polymers, α∥ decreases to values typical of polymer crystals (-1 × 10-5 K-1) and this can be attributed to the constraining effect of the crystalline bridges connecting the crystalline blocks. However, for polymers of lower crystallinity, α∥ may become an order of magnitude more negative and this remarkable phenomenon is attributed to the rubber-elastic contraction of taut tie-moleucles. Since taut tie-molecules and bridges have drastically different effects on α∥ at high temperatures, this allows a rough determination of their relative fractions.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.180190213
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  • 9
    Electronic Resource
    Electronic Resource
    Heat capacity of poly(vinylidene fluoride) and polytetrafluoroethylene between 5 and 200°K (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 87-94 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Heat capacities of poly(vinylidene fluoride) (PVF2) and polytetrafluoroethylene (PTFE) have been measured between 5 and 100°K with an accuracy of (1-5)% by adiabatic calorimetry. Calculations based on contributions from known optical lines and the Tarasov continuum model are in good agreement with experimental results down to 30°K for PVF2 and 10°K for PTFE, and yield characteristic temperatures θ1 and θ3 which are consistent with previous values determined from high-temperature (100 - 350°K) data. At lower temperature the measured heat capacity is significantly higher [(30-100)%] than the model prediction, and can be satisfactorily accounted for by the introduction of localized vibrators at a concentration of about 1% as compared to acoustical oscillators and at a characteristic temperature of about 20°K. Using established data on polyethylene for comparison, the principle of additivity for heat capacities is found to be valid down to at least 20°K, convering the region (〈60°K) where interchain vibrations contribute significantly to the heat capacity. Possible reasons for this unexpected behavior are discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.180170108
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  • 10
    Electronic Resource
    Electronic Resource
    Negative thermal expansivity of polymer crystals: Planar zig-zag chain model (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 971-981 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal expansivity of polymer crystals in the direction parallel to the chain axis α∥ is studied in a planar zig-zag chain model. Using values of force constants for polyethylene, it was found that α∥ = -1.3 × 10-5 K-1, in good agreement with experimental results. Torsional modes are found to contribute slightly more than half α∥. The expansivity is independent of the mass of the atomic groups on the chain and only weakly dependent on the interchain van der Waals interaction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.180190606
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