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  • NONMETALLIC MATERIALS  (3)
  • crosslinked domains  (1)
  • emulsifier-free  (1)
  • emulsion copolymerization, divinylbenzene  (1)
  • 1
    Publication Date: 2016-06-07
    Description: Large-particle-size monodisperse latexes were prepared on four STS missions of the space shuttles Columbia and Challenger using flight hardware comprising four automated 100 cm(3) polymerization reactors. Seven polymerizations carried out on the March 1982 STS-3 mission of the Columbia, and the April 1983 STS-6 and June 1983 STS-7 missions of the Challenger, gave monodisperse latexes of 5 to 18 micron diameter with narrower particle size distributions than the corresponding ground-based control polymerizations. The rates of polymerization in microgravity were the same as on Earth. The results of these experiments are reviewed, and the prospects of the development of a space production process are discussed.
    Keywords: NONMETALLIC MATERIALS
    Type: 2nd Symp. on Space Industrialization; p 75
    Format: text
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  • 2
    Publication Date: 2019-06-28
    Description: The research program achieved two objectives: (1) it has refined and extended the experimental techniques for preparing monodisperse latexes in quantity on the ground up to a particle diameter of 10 microns; and (2) it has demonstrated that a microgravity environment can be used to grow monodisperse latexes to larger sizes, where the limitations in size have yet to be defined. The experimental development of the monodisperse latex reactor (MLR) and the seeded emulsion polymerizations carried out in the laboratory prototype of the flight hardware, as a function of the operational parameters is discussed. The emphasis is directed towards the measurement, interpretation, and modeling of the kinetics of seeded emulsion polymerization and successive seeded emulsion polymerization. The recipe development of seeded emulsion polymerization as a function of particle size is discussed. The equilibrium swelling of latex particles with monomers was investigated both theoretically and experimentally. Extensive studies are reported on both the type and concentration of initiators, surfactants, and inhibitors, which eventually led to the development of the flight recipes. The experimental results of the flight experiments are discussed, as well as the experimental development of inhibition of seeded emulsion polymerization in terms of time of inhibition and the effect of inhibitors on the kinetics of polymerization.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-171267 , NAS 1.26:171267
    Format: application/pdf
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  • 3
    Publication Date: 2019-07-13
    Description: The objectives of this program are to apply ground-based emulsion polymerization reactor technology to improve the production of: monodisperse latex particles for calibration standards, chromatographic separation column packing, and medical research; and commercial latexes such as those used for coatings, foams, and adhesives.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-179179 , NAS 1.26:179179
    Format: application/pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 171-183 
    ISSN: 0887-624X
    Keywords: latex ; sulfonate functional groups ; poly(styrene-sodium styrene sulfonate) ; emulsion copolymerization ; emulsifier-free ; enhanced gel effect ; ion association ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the emulsifier-free emulsion copolymerization of styrene and sodium styrene sulfonate have been examined over a range of comonomer compositions. The rate of polymerization was found to increase dramatically in the presence of small amounts of sodium styrene sulfonate. This increase is attributed to the increased number of particles formed when sodium styrene sulfonate was present and to a gel effect enhanced by ion association. At low concentrations of functional comonomer, where a monodisperse product was obtained, a homogeneous nucleation mechanism of particle generation is proposed. At higher concentrations, broader and then bimodal size distributions were obtained, and this is ascribed to significant aqueous phase polymerization of sodium styrene sulfonate. The water-soluble homopolymer is supposed to act as a locus of polymerization. The occurrence of this aqueous phase side reaction and the generation of secondary particles makes impossible the preparation of highly sulfonated polystyrene latexes by batch or seeded batch emulsion copolymerization.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 235-244 
    ISSN: 0887-624X
    Keywords: monodisperse particles ; emulsion copolymerization, divinylbenzene ; porous particles ; macroporous structure ; linear polymer, diluent ; crosslinked domains ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monodisperse porous polymer particles in the size range of 10 μm in diameter were prepared via seeded emulsion polymerization. Linear polymer (polystyrene seed) or a mixture of linear polymer and solvent or nonsolvent were used as inert diluents. The pore diameters of these porous polymer particles were on the order of 1000 Å with pore volumes up to 0.9 mL/g and specific surface areas up to 200 m2/g. The physical features of the porous polymer particles depended on the diluent type and the crosslinker content, as well as the molecular weight of polymer seed particles. By varying the molecular weight of the linear polymer, monodisperse porous polymer particles with different pore size distribution could be synthesized. Polymer seed with a low degree of crosslinking instead of linear polymer could also be used to prepare monodisperse porous polymer particles with smaller pore volume and pore size.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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