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  • Polymer and Materials Science  (6)
  • ddc:650
  • 1975-1979  (6)
Collection
Keywords
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Graft polymerization of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid onto starch (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 2015-2023 
    Details
    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: Mixtures of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid (AASO3H) were graft polymerized onto starch by cobalt-60 irradiation, and the water absorbency and water solubility of the resulting products were determined. The conversion of monomers to polymer was nearly quantitative when pregelatinized wheat starch and a water solution of the two monomers were simultaneously irradiated (simultaneous irradiation conditions). Products with high water absorbency were obtained with equal weights of starch and total monomers when acrylamide:AASO3H ratios ranged from 9:1 to 1:3. Water solubility of these polymers was over 50%. Neither of the two monomers gave absorbent polymers when graft polymerized individually onto starch. Although highly absorbent products were also obtained at a total monomer:starch ratio of 2:5, ratios of 1:5 and lower gave products with poor absorbency. Neutralization of AASO3H with sodium hydroxide before graft polymerization drastically reduced both the water solubility and absorbency of the final products. A reaction with granular starch was also carried out under simultaneous irradiation with a total monomer:starch ratio of 2:5 and with equal weights of the two monomers. Conversion of monomers to polymer was once again nearly quantitative. To obtain good water absorbency from this granular product, it was necessary to first neutralize the AASO3H portion with alkali, then disperse the polymer in hot water, and finally dry the resulting water dispersion. Graft copolymers with good water absorbency were also obtained by adding preirradiated starch to a water solution of acrylamide and AASO3H, although only partial conversions of monomers to polymer were realized. Selected products from the various graft polymerizations were fractionated by extraction with either water or a 1% solution of sodium chloride. The synthetic polymer content of the resulting fractions and the percentage of AASO3H in the synthetic portion of each polymer were determined. The Mn of some of the synthetic polymers was also determined after removal of carbohydrate by enzymatic hydrolysis.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240909
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  • 2
    Electronic Resource
    Electronic Resource
    Graft copolymers of starch and mixtures of acrylamide and acrylic acid (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 3201-3204 
    Details
    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
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1976.070201123
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  • 3
    Electronic Resource
    Electronic Resource
    Graft polymerization of vinyl acetate onto starch. Saponification to starch-g-poly(vinyl alcohol) (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 229-240 
    Details
    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 polymerizations of vinyl acetate onto granular corn starch were initiated by cobalt-60 irradiation of starch-monomer-water mixtures, and ungrafted poly(vinylacetate) was separated from the graft copolymer by benzene extraction. Conversions of monomer to polymer were quantitative at a radiation dose of 1.0 Mrad. However, over half of the polymer was present as ungrafted poly-(vinyl acetate) (grafting efficiency less than 50%), and the graft copolymer contained only 34% grafted synthetic polymer (34% add-on). Lower irradiation doses produced lower conversions of monomer to polymer and gave graft copolymers with lower % add-on. Addition of minor amounts of acrylamide, methyl acrylate, and methacrylic acid as comonomers produced only small increases in % add-on and grafting efficiency. However, grafting efficiency was increased to 70% when a monomer mixture containing about 10% methyl methacrylate was used. Grafting efficiency could be increased to over 90% if the graft polymerization of vinyl acetate-methyl methacrylate was carried out near 0°C, although conversion of monomers to polymer was low and grafted polymer contained 40-50% poly(methyl methacrylate). Selected graft copolymers were treated with methanolic sodium hydroxide to convert starch-g-poly(vinyl acetate) to starch-g-poly(vinyl alcohol). The molecular weight of the poly(vinyl alcohol) moiety was about 30,000. The solubility of starch-g-poly(vinyl alcohol) in hot water was less than 50%; however, solubility could be increased by substituting either acid-modified or hypochlorite-oxidized starch for unmodified starch in the graft polymerization reaction. Vinyl acetate was also graft polymerized onto acid-modified starch which had been dispersed and partially solubilized by heating in water. A total irradiation dose of either 1.0 or 0.5 Mrad gave starch-g-poly(vinyl acetate) with about 35% add-on, and a grafting efficiency of about 40% was obtained. A film cast from a starch-g-poly(vinyl alcohol) copolymer in which homopolymer was not removed exhibited a higher ultimate tensile strength than a comparable physical mixture of starch and poly(vinyl alcohol).
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230121
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  • 4
    Electronic Resource
    Electronic Resource
    Graft polymerization of starch with mixtures of acrylonitrile and 2-acrylamido-2-methylpropanesulfonic acid (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 1387-1390 
    Details
    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
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240522
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  • 5
    Electronic Resource
    Electronic Resource
    Graft polymerization of styrene onto starch by simultaneous cobalt-60 irradiation (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 425-433 
    Details
    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: Starch-g-polystyrene copolymers have been prepared by the simultaneous 60Co-irradiation of starch-styrene mixtures, and copolymers have been characterized with respect to weight per cent polystyrene (% add-on) and also the molecular weight and molecular weight distribution of polystyrene grafts. In a typical polymerization, 4 g each of starch and styrene were blended with 1 ml water and 1.5 ml of an organic solvent; the resulting semisolid paste was irradiated to a total dose of 1 Mrad. With ethylene glycol, acetonitrile, ethanol, methanol, acetone, and dimethylformamide as the organic solvent, values for % add-on ranged from 24% to 29%. The highest % add-on (43%) and the highest conversion of styrene to grafted polymer (76%) were obtained when the organic solvent was omitted, and water alone was used. When water was also omitted, polymerization of styrene was negligible; however, graft copolymer was formed in the absence of water when either ethylene glycol or ethanol was added. Attempts were unsuccessful to achieve a % add-on greater than 43% by doubling the amount of styrene in the polymerization recipe. Mixtures of equal weights of starch and styrene are relatively nonvicious, but these mixtures thicken when either water or ethylene glycol is blended in. Reasons for this thickening action and the possible influence of thickening on the graft polymerization reaction were explored.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210209
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  • 6
    Electronic Resource
    Electronic Resource
    The binding of adenosine to polyuridylic acid in which uracil residues are chemically altered (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1065-1079 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of adenosine-14C to polyuridylic acid (poly(U)) and several modified poly(U)s has been studied by equilibrium dialysis. The poly(U) was modified by addition of appropriate reagents across the 5,6-double bond of the uracil ring to form the photohydrate, photodimer, dihydrouracil, the HOBr addition product and the HSO3- addition product. Modification of the uracil rings decreases the amount of adenosine which can be bound to the poly(U); the decrease in binding is a function of the fraction of uracil rings which have been changed. Using the expression S = S0(1 - αr)2 to relate the fraction of uracil rings modified (r) to the number of binding “sites” remaining (S), it is found that α is about 1 for all the modifications except photodimer where it is about 2. These observations are taken to mean that the loss of binding capacity of the poly(U) resulting from modifications of the uracil ring is caused by loss of planarity of the uracil rings caused by the modifications, and consequent loss of double helix structure, but that for all modifications except photodimer there is no disruption of the poly(U) double helix on either side of the leison. There does appear to be local melting on either side of the photodimer lesion. The sigmoidal binding isotherms (Ab versus Ca) of modified and unmodified poly(U) can be approximated closely by the following equation: (1)\documentclass{article}\pagestyle{empty}\begin{document}$$ \theta = \frac{{A_{\rm b} }}{S} = \frac{{(K_1 C_{\rm a} )^n \left[ {\frac{n}{{1 - K_1 C_{\rm a} }}} \right] + \frac{{K_1 C_{\rm a} }}{{(1 - K_1 C_{\rm a} )^2 }}}}{{1 + (K_1 C_{\rm a} )^n \left[ {\frac{n}{{1 - K_1 C_{\rm a} }}} \right] + \frac{{K_1 C_{\rm a} }}{{(1 - K_1 C_{\rm a} )^2 }}}} $$\end{document} (1) where Ab = bound A, Ca = free A, n = minimum number of adjacent A′s in complex, S = concentration of sites on poly(U), and K1 = (Km)1/m for all m ≥ n.The stacking energy of adenosine (w) can be calculated accurately using the following equation, where dθ/d ln Ca is obtained from Eq. (1). (2)\documentclass{article}\pagestyle{empty}\begin{document}$$ {{d\theta } \mathord{\left/ {\vphantom {{d\theta } d}} \right. \kern-\nulldelimiterspace} d}\begin{array}{*{20}c} {{\rm }\ln {\rm }C_{\rm a} {\rm } = {\rm }{1 \mathord{\left/ {\vphantom {1 {re^{ - {w \mathord{\left/ {\vphantom {w {2RT}}} \right. \kern-\nulldelimiterspace} {2RT}}} }}} \right. \kern-\nulldelimiterspace} {re^{ - {w \mathord{\left/ {\vphantom {w {2RT}}} \right. \kern-\nulldelimiterspace} {2RT}}} }}12RT} & {at{\rm }\theta {\rm } = {\rm }0.5} \\\end{array} $$\end{document} (2) For unmodified poly(U), w is -2.0 kcal/mole and ΔG° (-;RT ln K1) is -3.2 kcal/mole. The difference (-1.2 kcal/mole) is attributed to hydrogen bonding. Heavily photohydrated poly(U) does not bind guanosine or guanosine-5′-phosphate.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140514
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