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  • Polymer and Materials Science  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 677-695 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Liquid phase pairs were found in which polystyrene (PS) and styrene-acrylonitrile (SAN)-copolymers with an AN-content up to 13 wt.-% can be partitioned. They could be used for the fractionation of the copolymers according to chemical composition. The phase pairs are composed of 4 solvents, cyclohexane and nitromethane to form the phases and two solvents for the polymers. The partition ratio was measured as a function of the composition of the phase pairs, the molecular weight of PS, and of the AN-content of the copolymers. The phase composition at which a polymer is equally distributed into both phases depends on the chemical composition of the polymer but not on its molecular weight. With other phase compositions the partition equilibrium is shifted to one phase or the other the more the degree of polymerisation increases. Based on the partition equilibrium, fractionation methods are proposed to separate the SAN-copolymers according to their chemical composition if their molecular weight is high enough (〉about 105). The conditions which determine fractionation more by molecular weight or more by chemical composition are discussed.
    Additional Material: 5 Tab.
    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 25 (1980), S. 783-794 
    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: Graft copolymerization of acrylonitrile onto a soluble wool keratin derivative was studied with the reduced and carboxymethylated low-sulfur protein fraction from wool. Copolymerization was carried out under a variety of conditions with a redox system of (NH4)2S2O8-Na2SO3 in 60% (w/w) aqueous ZnCl2 solution at 10°C. Monomer conversions higher than 90% were obtained by the stepwise addition of initiator. The graft products were successfully separated into grafted copolymer and homopolyacrylonitrile (PAN) by fractional precipitation or solvent extraction with DMF. Grafted PAN were isolated by acid hydrolysis of the keratin backbone. Characterization of grafted and homo-PAN was carried out by IR spectroscopy, amino acid endgroup analysis, and viscometry. On the basis of the results, effects of polymerization conditions on grafting parameters were discussed. Membranes were prepared from 60% aqueous ZnCl2 solution by using ice-cold water as the regenerating medium. All the membranes formed from the graft products were transparent. Observation by scanning electron microscopy showed that the surface consisted of rather spherical keratin domains regularly distributed in the PAN matrix. Selective hydrolysis of the keratin domains allowed a new type of porous PAN membrane to be obtained, with the inner walls of the pores being charged with amino acid residues attached to PAN chains as the endgroup.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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