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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of α-Methyl Styrene Oxide initiated by trityl hexachloroantimonate is reported upon. Data is presented on side reactions, percent yield and molecular weight of polymer produced in the polymerization.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The peak separation in gel-permeation chromatography (GPC) is attributed to the contributions of the steric exclusion and the lateral diffusion processes. The advantage of using the distribution coefficient KGPC of the solute molecule in interpreting the GPC separation mechanism is assessed. The physical significance of KGPC and its relation to measurable GPC parameters are examined in detail. A simple mixing experiment for determining the exclusion effect is described. The results of this experiment, as well as those of the flow rate study, show that the exclusion effect plays the primary role in GPC peak separation. For a column packed with Bio-Rad porous glass of 200 Å designation, the diffusion effect does not contribute significantly to peak separation. However, for the case of a Waters Associates column packed with polystyrene gel of 104 Å designation, both the exclusion and the diffusion effects are shown to be important. A diffusion theory which includes the concept of a restricted diffusion coefficient is proposed to interpret the diffusion effect observed in the polystyrene gel column. The results of the theoretical calculation are found to agree with the observed flow rate dependence of the calibration curve.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0887-6266
    Keywords: polyimides ; reflectivity ; moisture absorption ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Water absorption in thin films (〈1000 Å) of a commercial polyimide was evaluated by monitoring dimensional changes induced by a humid environment. Film thickness was measured using x-ray reflectivity, which is a nondestructive technique offering angstrom resolution in the measurements of thin film or multilayer thickness. The effect of several variables on the absorption of moisture were monitored in polyimide films adhered to polished silicon substrates, including total dry film thickness, exposure time, and the contribution of a coupling agent. The percentage increase in film thickness due to moisture uptake is found to be a weak function of dry film thickness, decreasing as dry film thickness increases, and to be somewhat affected by the use of an interfacial coupling agent. The observed behavior points to the polymer/substrate interface as a strong factor controlling the absorption of moisture in the polyimide/silicon system, and is believed to reflect the presence of a highly moisture-saturated interfacial layer. A bilayer model is proposed, and the feasibility of using this model to describe the observed behavior is considered. Published 1998 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America. J Polym Sci B: Polym Phys 36: 155-162, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1040-0397
    Keywords: Microelectrode ; Array electrode ; Conducting polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An individually addressable microelectrode array system has been developed in the course of this work. The performance of this system was investigated using conventional electrochemistry (oxidation/reduction or ferrocene carboxylic acid) to demonstrate that independent potential control and current measurement at each of the array components was possible. The practical utility of this system has been demonstrated using a conducting polymer based microarray detection system subsequent to Ion Chromatography. The detection of simple electroinactive ions (e.g., Cl-, SO42-, K+, NH4+) using the array system was achieved and the response at each of the array components was studied as a function of polymer composition.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Previously, the angular positions of the extrema of the polarization ratio have been utilized in light-scattering studies as a method of particle-size analysis under the assumption of monodisperse, spherical particles. Since the consequences of the existing finite polydispersity on this method of analysis was not assessed, the results are questionable. This work is concerned with (1) reporting the quantitative effects of a finite polydispersity on the method of analysis, (2) pointing out previous misuse of the method, and (3) revising the method of analysis to include polydispersity and the exact Mie calculations. The method will then permit the characterization of a scattering system in terms of a modal diameter and a distribution-width parameter by utilizing prepared diagrams for a particular relative refractive index.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The glass transition temperature Tg of partially sulfonated polystyrene has been measured dilatometrically as a function of degree of sulfonation. A semitheoretical relationship between Tg and degree of sulfonation has been derived by treating the strong-acid polymer as a highly polar copolymer of styrene and styrenesulfonic acid. The Tg of copolymer has been found to increase linearly up to 0.15 weight fraction of styrene-sulfonic acid wA as given by: \documentclass{article}\pagestyle{empty}\begin{document}$ T_g = T_{gB} + 200w_A $\end{document} where TgB is the glass transition temperature of loosely crosslined (1%) polystyrene matrix. Our experimental results agree well with theoretical relations developed on the basis of the iso-free-volume state of glass transition applied to sulfonated polystyrene. The marked linear increase in copolymer Tg with the styrenesulfonic acid is accounted for by the effect of progressively higher intermolecular forces due to the highly polar sulfonic acid substituents.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Recent literature reports from three laboratories have treated the refraction correction for the Sofica and a noncommercial light scattering photometer. Our re-evaluation of the data contained in these reports, as well as our experiments, indicate that the usually cited n2 refraction correction has not been unquestionably established for these instruments. In some cases, imprecise experimental techniques have been used to support this particular form of the correction. In addition, we find the optical system of the Sofica instrument results in the detector seeing vertically past the horizontal edge of the illuminated volume in violation of a basic assumption in the deduction of the n2 correction. Our experiments, as well as our interpretation of recent literature data, support an exponent of less than 2.0 for the Sofica apparatus, which is consistent with an instrument whose detector views outside the illuminated volume. However, the experimental methods available to evaluate the exponent lack the desired precision.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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