INVESTIGATION OF TRANS-1,4 POLYISOPRENE CRYSTALS FROM SOLUTION: MORPHOLOGIES AND QUANTITATIVE CHARACTERIZATION.
Item
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Title
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INVESTIGATION OF TRANS-1,4 POLYISOPRENE CRYSTALS FROM SOLUTION: MORPHOLOGIES AND QUANTITATIVE CHARACTERIZATION.
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Identifier
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AAI8801777
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identifier
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8801777
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Creator
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XU, JIA-RUI.
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Contributor
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Arthur E. Woodward
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Polymer
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Abstract
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Trans-1,4 polyisoprene (TPI) structures in the {dollar}\alpha{dollar} and {dollar}\beta{dollar} crystalline forms with various morphologies were prepared using different crystallization procedures. Optical microscopy and scanning electron microscopy were used to investigate these preparations after treatment in suspension with OsO{dollar}\sb4{dollar}. Changes in morphology with molecular weight, crystallization temperature and time were followed; curved lamellae, lamellar stacks and spherulites were found. Scanning electron microscopy revealed features, such as lamellar interpenetration and curvature, branching, and twisting, either not seen or not seen clearly with optical microscopy. The effects of molecular weight, crystallization temperature and annealing treatment on the length of the crystalline stem and the non-crystalline traverse for these TPI structures were quantitatively characterized using epoxidation followed by {dollar}\sp{13}{dollar}C NMR analysis in solution. Preliminary studies were carried out to determine the optimum conditions for quantitative reaction of the double bonds at the lamellar surfaces. Results were obtained suggesting that for many liquids penetration of partially reacted lamellae can take place from the lateral surfaces; reactant concentration and time were also shown to be important and conditions were found that gave agreement between the fraction reacted and the noncrystalline content from infrared and density measurements. An epoxidation mechanism based on the experimental results was proposed. The results of {dollar}\sp{13}{dollar}C NMR analysis showed that the fold surfaces of these TPI lamellae were loose with an average fold length of 9 monomer units. For the multilamellar structures, interlamellar traverses were detected with the amount increasing with increasing molecular weight. The nature of chain folding in these structures and in the trans polydienes is discussed.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
