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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 347-355 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Light scattering has been used to investigate the structure of human tracheobronchial mucin glycoproteins (HTBM) from the sputum of cystic fibrosis patients. The specimen was extracted using 6M guanidinium hydrochloride solution and fractionated by gel exclusion chromatography on Sephacryl S-1000. The fractionated HTBM was purified by density gradient ultracentrifugation. Purity of the resulting material was confirmed by SDS polyacrylamide gel electrophoresis and uv spectroscopy. Light scattering measurements on the fractionated mucins yield weight-average molecular weights Mw, and z-average radii of gyration Rg, z. The native cystic fibrosis HTBM consisted of a high molecular weight fraction with Mw = 9.3 × 106 daltons and a lower molecular weight fraction contanining partly degraded mucins. After reduction and carboxymethylation of the high molecular weight native fraction, the resulting material was separated into three pools with Mw values of 5.1 × 106, 1.6 × 106, and 400,000. The derived molecular weights for the protein cores Mp,w, and the experimental radii of gyration are found to be consistent with the Mp,w - Rg relation established previously for submaxillary, cervical, and gastric mucins. These results imply that HTBM has the same extended-coil conformation reported for other mucins and has a molecular structure consisting of subunits, linked into linear chains via covalent (disulfide) bonds.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 1293-1299 
    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 individual, competitive, and displacement adsorption of polyvinyl alcohol (PVOH), hydroxyethyl cellulose (HEC), and hydroxypropylmethyl cellulose (HPMC) in aqueous solution onto an attapulgite clay has been systematically studied. For the individual adsorption experiments, the amount of polymer adsorbed at equilibrium decreased in the order PVOH, HEC, HPMC. In the competitive adsorption experiments, the adsorption level of each polymer is diminished by the presence of a competing polymeric species. Binary mixtures of a cellulosic polymer (HEC or HPMC) with PVOH result in a substantial reduction in the amount of cellulosic polymer adsorbed. In the displacement adsorption studies, the sequential addition of HEC or HPMC is not able to displace previously adsorbed PVOH molecules to any appreciable extent. However, the addition of PVOH to previously equilibrated HEC/clay or HPMC/clay suspensions results in a large amount of the adsorbed cellulosic polymer being displaced by PVOH, especially under conditions of high surface coverage. These results indicate that PVOH is preferentially adsorbed on the clay surface and the strength of attachment to the surface is greater for PVOH than for either cellulosic polymer.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 49 (1993), S. 1131-1144 
    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 structural properties of epoxy can be retained and thermal stability improved by blending epoxy with bismaleimide (BMI) and curing them simultaneously. Depending on the curing agent, the overall viscoelastic properties of the cured material can be varied. In the present work, diaminodiphenylmethane and diaminodiphenyl sulfone have been used as curing agents to prepare blends of epoxy and BMI. The blends were characterized by DSC, TG, DMA, and SEM. Results indicate that an excellent interpenetrating network forms in both the cases and that the DDM-cured system gives better thermal stability than that of the DDS-cured system. © 1993 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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