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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 19 (1981), S. 1329-1336 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of pentaerythritol (1) or dipentaerythritol with caprolactone yields prepolymers of the general structure \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C} { \left( {\rm CH}_2 {\rm OH} \right)_4 } \hbox{--} {\rm i} \left [ {\rm CH}_2 {\rm O} \left( {\rm COCH}_2 {\rm CH}_2 {\rm CH}_2 {\rm CH}_2 {\rm CH}_2 {\rm O} \right)_{\rm n} {\rm H} \right]_{\rm i}$$\end{document} for i = 1, 2, 3, and 4 (2)-(5). The 13C chemical shifts of the quaternary carbons in (1)-(5) differ by more than 0.5 ppm. Conditions were determined to obtain quantitative intensity ratios of these carbons. The relative intensities give the distribution of the various branched structures and permit calculations of the average number of caprolactones per branch. Results are reported for caprolactone/polyol mole ratics of 3-66.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2006-06-11
    Description: Microgravity offers a unique environment for studying polymer diffusion and polymer polymerization reactions. The absence of convection currents, which are the major mode of mixing at the molecular level on Earth, are eliminated or reduced in the microgravity environment. More importantly, the prediction of unique copolymer composition development in microgravity allows controlled formation of new compositions of matter. The absence of mixing at the molecular level should produce unique short block copolymers available for the first time for comonomer compositions which normally lead to random or long block copolymer under good mixing. The investigation of fundamental polymer diffusion and polymer polymerization processes in microgravity is proposed. This effort will involve fundamental studies of monomer and polymer diffusion; their effects on initiation, propagation, and especially termination kinetics rate constant; and the accurate evaluation of copolymerization reactivity ratios in microgravity. The experimental design is presented for these studies along with an evaluation technique for in situ monitoring of polymer diffusion and polymerization kinetics.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Lewis Research Center, NASA Laser Light Scattering Advanced Technology Development Workshop, 1988; p 215-227
    Format: text
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