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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 2151-2165 
    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: An investigation has been carried out for determining the effect of coupling agents on the mechanical properties of polymer-impregnated mortars. Mortar specimens were impregnated with methyl methacrylate (MMA) monomer and α, α-azobis-isobutyronitrile initiator, and polymerized thermally in water. Three titanate coupling agents, KR-33CS, KR-55, and KR-138s, and one silane coupling agent, the A-174, were used for the investigation. Varying amounts of coupling agent were used in impregnating the mortars in situ or in pretreating the mortars with a solvent system. Bulk polymerization of MMA shows no appreciable influence of the coupling agents in the reaction kinetics; however, with the exception of KR-138S, all polymers obtained in the presence of coupling agents came out as insolble. Similar results were obtained for polymers extracted with acetone from mortars. The mechanical property results show an improvement of properties in mortars containing 5.0 vol% of KR-33CS and A-174 after impregnation in situ. A slightly better improvements of mechanical properties were obtained by pretreating the mortar specimens with acetone or toluene/xylene containing coupling agents. Microscopic observation of the fracture surface showed no noticeable difference in the surfaces prepared with and without coupling agents.
    Additional Material: 4 Ill.
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  • 2
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Inter-proton long-range and ring couplings were measured in o-anisaldehyde and in seven disubstituted anisoles. In order to investigate the transmission mechanisms of long-range couplings with the methoxy group, partially restricted molecular orbital (PRMO) calculations were carried out within the FPT-INDO method on o-anisaldehyde. σ- and π-electron, and through-space transmitted components were separated. For the energetically favoured trans-OMe conformation a through-space component was found for the couplings of the methyl protons with the ortho-proton, and it was found that its sign, as well as its magnitude, depends on their relative positions. If free rotation, however, is assumed for the methyl group, the averaged value for this coupling constant is negative.
    Additional Material: 2 Ill.
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  • 3
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The identification of (E)-2-methylglutaconic acid, a ‘new’ metabolite of isoleucine, is described. The substance was detected in urine samples from patients with propionic acidaemia, methylmalonic acidaemia and so-called β-ketothiolase deficiency; in the majority of cases together with N-tiglylglycine. (E)-2-Methylglutaconic acid is thought to be the end product of the 3-methylcrotonyl-CoA carboxylase-catalysed carboxylation of tiglyl-CoA. Prerequisites for the quantitative gas chromatographic analysis of the unstable 2- (and 3-) methylglutaconic acid ditrimethylsilyl ester are given.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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