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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 1773-1779 
    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: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 1128-1132 
    ISSN: 0006-3592
    Keywords: lipolytic rates ; hydrolysis ; tributyrin ; Candida rugosa ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dramatic change of the reaction rate was observed for the lipase-catalyzed hyrolysis of tributyrin in a batch reactor. Immediately after the addition of the enzyme, the lipolysis rate increased continuously until a maximal reaction rate was reached. The duration of the induction was mainly controlled by the bulk enzyme concentration and the reactor stirring speed. The reaction rate dropped sharply after reaching its maximal value. The lipolysis decayed at a rate of about 0.012 min-1, and was not affected by changes of the stirring speed. This decay was attributed to the fast deactivation of the surface-adsorbed lipase, and possibly to the extremely slow desorption of the inactivated species. For reaction time longer than 120 minutes, the lipolysis decreased at a much slower rate. Several mechanisms for the decay of the lipolysis rate were discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Thin (750 Å) plasma-polymerized films of acetylene were deposited onto polished steel substrates in an inductively coupled r.f. reactor. The films were characterized by x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS) immediately after deposition and after aging in the atmosphere. The FTIR spectra of the as-deposited films were characterized by bands related to mono- and disubstituted acetylene groups and by bands related to methyl and methylene groups. During exposure to the atmosphere, bands related to acetylenic groups decreased in intensity while new bands due to carbonyl groups appeared. When XPS spectra were obtained from films that were exposed to the atmosphere, new components assigned to oxidation products were observed in the C 1s spectra that were not observed for as-deposited films, verifying that oxidation had occurred. Numerous peaks related to aromatic structures were observed in positive SIMS spectra of as-deposited films. Results obtained from AES showed that the plasma-polymerized films were continuous and that the oxide on the substrate surface was partially reduced during deposition.Plasma-polymerized acetylene films were excellent primers for rubber-to-steel bonding. Miniature lap joints were prepared by using rubber as an ‘adhesive’ to bond together pairs of polished steel adherends primed with plasma-polymerized acetylene films. The force required to break the as-prepared joints was ∼2000 N for a bonded area of 64 mm2 and failure was 100% cohesive in the rubber. Similar results were obtained for joints prepared using polished brass substrates.Because of the complexity of reactions between rubber and the plasma-polymerized primer, a model ‘rubber’ consisting of a mixture of squalene, zinc oxide, carbon black, sulfur, stearic acid, cobalt naphthenate, N,N-dicyclohexylbenzothiazole sulfenamide and diaryl-p-diphenyleneamine was used to simulate the cross-linking reaction. The results obtained using XPS, SIMS, AES and FTIR showed that sulfur diffused through the primer to form a layer of sulfide at the primer/substrate interface. Zinc and cobalt sulfides and perthiomercaptides, which formed at the interface between squalene and the plasma-polymerized acetylene primer, catalyzed the reaction between squalene and the primer. Cross-links between squalene and the primer were mostly mono-sulfidic, although some evidence for di- and trisulfidic cross-links was observed.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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