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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of epoxy-surfactant interactions (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2781-2792 
    Details
    ISSN: 0887-6266
    Keywords: waterborne epoxy ; surfactant ; cooperativity ; Fox equation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We have investigated epoxies based on the diglycidyl ether of bisphenol A (DGEBA) cured with 2-ethyl-4-methylimidazole (EMI-24) in the presence of the nonionic surfactant Triton X-100. A goal was to determine if the viscoelastic properties of the epoxy-surfactant system differed when prepared in bulk form, as opposed to being cast as a thin film on the surface of E-glass cloth. Such a combination of materials has generated great interest for potential use in the construction of laminated circuit boards. Using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and atomic force microscopy (AFM), it was determined that the surfactant acts as a plasticizer and is miscible with the epoxy system in concentrations up to 15% by weight. The glass transition temperature (Tg) depression of the epoxy due to the surfactant was accurately described by the Fox equation. DMA master curves were constructed in the frequency domain. The temperature dependence of the shift factors was used to determine the fragility of each of the samples studied. It was found that the fragility (cooperativity) of the epoxy decreased as the concentration of surfactant increased, presumably due to a reduction of intermolecular constraints. The fragility of the combined epoxy-surfactant system increased when cast on the surface of the E-glass cloth. Results for our model epoxy-surfactant resin were in excellent agreement with those obtained using a commercially available aqueous waterborne epoxy resin. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2781-2792, 1998
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Synthesis of hydroxyl-terminated polycarbonates of controlled number-average molecular weight (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 2289-2301 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydroxyl-terminated polycarbonates are important starting materials for the synthesis of multiblock copolymers. Earlier papers from our laboratory and elsewhere have demonstrated their utility in siloxane, aryl ether, and ester systems. One synthesis problem that must be addressed is the control of the number-average molecular weight and hence block size of the polycarbonate oligomeric precursor. The facile phosgene-hydroxyl reaction is often difficult to monitor precisely. The present article describes a novel, simple, and convenient technique for the synthesis of hydroxyl-terminated polycarbonates of well-controlled number-average molecular weight. The approach involves an in situ blocking of some of the phenolic groups either prior to or during phosgenation. The protecting groups are easily removed after the polymerization is complete. In a practical laboratory experiment the technique does not require any additional step beyond that necessary for the preparation of nonfunctional polycarbonates of controlled molecular weight. The method is demonstrated in this article with the polycarbonate of bisphenol-A via the use of trimethylchlorosilane, trifluoroacetic anhydride, and trifluoroacetic acid as blocking groups. Ultraviolet, 19F-NMR, and 1H-NMR measurements as well as vapor-pressure osmometry were used to characterize the oligomers.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170200831
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