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  • 1
    Electronic Resource
    Electronic Resource
    The stability of poly(ether urethane)/polydimethylsiloxane interpenetrating polymer networks (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 733-740 
    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: Interpenetrating polymer networks (IPNs) are a special type of polymer blend consisting of two polymer networks synthesized and/or cross-linked independently within each other. One potential approach for the preparation of composite materials from polymers having desirable physical characteristics obtained by modifying their surfaces with physiologically acceptable polymers involves IPN technology. An IPN based on a poly(ether urethane) and polydimethylsiloxane has been synthesized and charaterized using optical microscopy, dynamic mechanical analysis, and scanning electron microscopy. The stability of poly(ether urethane)/polydimethylsiloxane composites were studied in hydroxyl radical aqueous solutions over 30 weeks. The data suggest that these composites have good potential for biomedical applications. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070550509
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of radiation on mechanical properties of polybutadiene/polystyrene blends (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 85-94 
    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: Blends containing 3 wt % low molecular weight polybutadiene (PB) in a polystyrene (PS) matrix were prepared via a precipitation technique that yielded spherical, submicron pools of PB. Tensile specimens made from these blends were then irradiated with high energy electrons in air at dose levels from 0 to 70 Mrads. The blends, which previously showed high levels of toughness approaching that of high impact PS, lost all enhanced toughness when irradiated above 10 Mrads. Analysis of pure PS specimens irradiated over the dose range from 0 to 45 Mrads showed no appreciable dependence of mechanical behavior on dose level. Molecular weight studies of the polybutadiene demonstrated only a very modest increase in molecular weight in the dose range studied here; therefore, reduced mobility of the PB in the blends was not the reason for the dramatic drop in toughness with radiation dose. It was concluded that radiation-induced scission of the PS near the surface of the blends resulted in a significant local reduction in molecular weight. This degraded layer led to premature craze failure and hence a low level of toughness. It was demonstrated that the absence of oxygen during the irradiation process or the removal of the scissioned surface layer via mechanical abrasion resulted in a recovery of toughness. © 1995 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580109
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Cyclopolymerization studies of diallyl-and tetraallylpiperazinium salts (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 1077-1085 
    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: The quaternary ammonium salt 1,1-diallyl-4-formylpiperazinium chloride (7) was synthesized in good yields. The monomer (7) on cyclopolymerization in the presence of ammonium persulfate in water solution at 90°C afforded water-soluble polymer (8) having excellent rheological properties. The synthesis of the polymer (8) paves the way for the preparation of a novel class of polymers: dicationic polyelectrolytes (9) and cationic polymer (10) with a basic nitrogen as well as a quaternary nitrogen. Effects of monomer, initiator, and additives concentration were studied. Cyclopolymerization of (7) with 1,1,4,4-tetraallylpiperazinium dichloride (12) gave ion-exchange resins with excellent swelling coefficients. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetic and mechanistic studies on the complexation and anation of dioxotetracyanomolybdate (IV) with 2,2′-bipyridyl in aqueous solution (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 28 (1996), S. 705-711 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dioxotetracyanomolybdate(IV) has been found to form a 1 : 2 complex with 2,2′-bipyridyl. The kinetics of the reaction has been studied over the pH range 5.3-8.7 by visible spectrophotometry under pseudo conditions. The effect of the 2,2′-bipyridyl and dioxotetracyanomolybdate(IV), temperature, ionic strength, and pH on the reaction rate was determined. The reaction follows first-order kinetics with respect to dioxotetracyanomolybdate(IV) ion and fractional-order kinetics with respect to 2,2′-bipyridyl. Values for the outer-sphere complex formation constant (Kos2) and rate constants (k2) were also calculated from the kinetic data. It was found that rate of the reaction increases with the decreasing pH. The following rate equation based on the outersphere complexation equilibrium preceding the associative interchange has been derived.\documentclass{article}\pagestyle{empty}\begin{document}$$\rm {{1}\over{{\it k}_{obs}}}={{1+K_{a2}[H^+]}\over{B_1[2,2\prime-bipyridyl]}}+B_2$$ ${\rm where}$ $\rm B_1={\it k}_1K_{os1}+{\it k}_2K_{os2}[H^+]K_{a2}$ ${\rm and}$ $\rm B_2={{K_{os1}+K_{a2}K_{os2}[H^+]}\over {{\it k}_1K_{os1}+{\it k}_2K_{os2}[H^+]K_{a2}}}.$\end{document}On the basis of the observed results probable mechanism has been proposed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.9
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  • 5
    Electronic Resource
    Electronic Resource
    Photoreactivity of diethanolamine with octacyanomolybdate(IV) and -tungstate(IV) (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 29 (1997), S. 819-824 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An investigation is presented on the kinetics of complexation of aqueous solution of octacyanomolybdate (IV) and -tungstate (IV) after photoinitiation with one of the mixed group ligands containing both N and O, diethanolamine (DEOA), [NH(CH2CH2OH)2]. Under the steady state conditions and with approximation k3 〉 k4 over a range of concentrations, the observed rate law is:\documentclass{article}\pagestyle{empty}\begin{document}$$ \cal{k}_{\rm obs.}={\cal{k}_{2}\cal{k}_{4}\rm {I}_{a}[\rm {OH}^{-}][\rm {NH}(\rm{CH}_{2}\rm{CH}_{2}\rm{OH})_{2}]\over \rm{I}+\it \cal{k}_{2}[\rm {OH}^{-}]} $$\end{document}The complexes show shift in electronic transition supporting the mechanism of association of the ligand followed by the abstraction of some small molecules and then substitution by the ligand. The presence of the specific isobestic point also contributes towards the stability of the complex. The rate constant and quantum yield values are dependent on both the concentration of the metal cyanide and the ligand predicting the mechanism to be an associative one. The complexes have strong absorption in the visible range and are assigned metal-to-ligand electron transfer transition. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 819-824, 1997
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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