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  • 1
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Lithium alkyls and phenylmagnesium bromide, in toluene, and lithium-naphthalene, in dimethoxyethane, polymerize tert-butyl crotonate. Sodium naphthalene produces only low polymer (Mn 〈3000), and potassium naphthalene gives no polymer. Even lithium naphthalene, which polymerized tert-butyl crotonate readily, fails to polymerize tert-butyl tiglate. Free radicals polymerize neither tert-butyl crotonate nor tert-butyl tiglate. Poly(tert-butyl crotonate) formed in the presence of lithium naphthalene is noncrystalline, in the presence of lithium alkyls, either noncrystalline or partly crystalline, and in the presence of phenylmagnesium bromide, highly crystalline. Poly(crotonic acid) was prepared from poly(tert-butyl crotonate).
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ability of various polymers to acquire persistent polarization (i.e., to become electrets) was investigated. Polarization was induced in the polymers by two methods: (a) by cooling under a voltage drop and (b) by cooling with flow under pressure. There was found to be an optimum temperature for electret formation by either method. This optimum temperature was roughly 37°C. above Tg when polarization was produced by application of a voltage drop and roughly 57°C. when polarization was produced by flow under pressure. Crystallinity and the nonhomogeneities present in blended polymers were harmful to electret formation, but a small critical amount of ionic impurity was helpful.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Depolarization currents were used to study the persistent polarization induced in polystyrene and poly(methyl methacrylate) by cooling with flow under pressure. These studies showed that the charge on electrets made by flow under pressure consists in part of a surface charge which leaks off rapidly in moist air and in part of a charge due to volume polarization which decays more slowly. The volume polymerization produced in poly(methyl methacrylate) by flow under pressure is of the same order as that produced by cooling under a voltage drop, but flow under pressure produces a larger surface charge.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 627-634 
    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 coagulating and regenerating conditions that are necessary for the formation of a highly durable cellulosic film are described. It is shown that low orientation, low lateral order, low gel swelling, and cellulose with a high DP are primary requisites for best film properties. Experiments demonstrated that the application of a unidirectional stress produced an unbalance of physical properties in the film, and this, in general, had an adverse effect on the durability level of a packaging film. Studies of the rates of loss of water and sodium hydroxide from the viscose during coagulation revealed that thermal and osmotic effects were not as important in determining the rate of coagulation as was the buffering and neutralizing capacity of the bath. A bath with high acid content caused the cellulose to be regenerated prior to collapse of the sheet.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 1 (1979), S. 149-160 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A computer-controlled atom prove time-of-flight mass spectrometer system is described which permits quantitative microanalysis to be undertaken at the 1-2 nm level. Distinctive features of the system include the use of a Johnston detector, to give low noise, high gain and high detection efficiency; incorporation of a movable channel plate and screen assembly, to provide a variable aperture; and the development of a comprehensive set of computer plate and screen assembly, to provide a variable aperture; and the development of a comprehensive set of computer software, to assist in the processing of data and presentation of analytical results. The system has been used successfully in a number of metallurgical investigations. In this paper, particular attention is given to describing the operating conditions required to achieve optimum performances, and to discussing the questions of background noise reduction and the deconvolution of spectra. The quantitative analysis capability of the instrument is demonstrated by reference to the results obtained from a range of standard materials, including steels. Applications to problems of metallurgical interest are illustrated by the analysis of ultra-fine particles in a Cu/Co alloy, and the analysis of carbides and carbide-matrix interfaces in a 2¼Cr/1Mo steel. The spatial resolution obtainable under different operating conditions is discussed, and the particular problems involved in the study of interfaces by this technique are described in detail.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The surface reactivity of hydroxyl groups on silica with trimethylchlorosilane (TMCS) is examined using XPS, FTIR-PAS, and solid state NMR. All techniques give responses give responses which can be correlated with increasing TMS surface coverages on Lichrosorb Si 60 silica and provide detection limits of ≤10% of a TMS monolayer. Solid state NMR is particularly suited to examining reactivity differences between geminal and single silanols. Geminal hydroxyl groups are found to be much more reactive. At higher TMS coverages approaching steric limitations (0.5 TMS monolayer), nearly 100% of the geminal sites are reacted as opposed to only 20% of the single sites. The reactive subset of single silanols appears to include hydrogen-bonded (vicinal) groups. A mechanism is postulated to explain the apparent enhanced reactivity of geminal and vicinal silanols.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Radiotagged acrylamide was polymerized in a solution containing untagged polyacrylamide in order to study branch formation. Polymerizations were carried out at 50°C. and at 78°C. with a persulfate-bisulfite catalyst. At 78°C., polymer with from one to seven branches was formed, while at 50°C. even with larger amounts of catalyst, the polymer was almost exclusively linear. The intrinsic viscosity of branched polyacrylamide, in water at 30°C., was compared with the predictions of the Zimm and Stockmayer equation for the intrinsic viscosity of trifunctionally branched molecules. This equation gave values which agreed well with measured values of the number of branches.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymerization of acrylonitrile with n-butyllithium in toluene at -78°C. was studied at three monomer concentrations, 5.7, 13, and 27%, and at butyllithium concentrations from 0.5 to 1.5 × 10-2 m./1. With high concentrations of monomer the conversion was reduced by a gel effect. At low monomer concentrations the dependence of polymerization rate on monomer and catalyst concentration was similar to the dependence observed by other workers in the polymerization of styrene with butyllithium at 20-30°C. At -78°C. in toluene there was no evidence for termination of polyacrylonitrile chains by monomer. Cyanoethylation and reactions which produce yellowing at higher temperatures were absent. The initial polymerization was rapid and the initial catalyst efficiency low. Molecular weights were from 250,000 to 1,300,000.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crystalline poly(tert-butyl acrylate) was prepared with lithium dispersions, n-butyllithium, and lithium plus n-butyllithium as catalysts. Methyl acrylate, n-, see-, and iso-butyl acrylate gave only amorphous polymer under the conditions that produced crystalline poly(iert-butyl acrylate). Very pure monomer was necessary for the preparation of crystalline poly(tert-butyl acrylate) with lithium dispersions. That the poly(tert-butyl acrylate) was crystalline was shown by x-ray diffraction, observation with the polarizing microscope (preparation of birefringent spherulites) and the electron microscope, study of infrared absorption, softening point, and density, and finally by preparation of crystalline polymethyl acrylate from crystalline poly(tert-butyl acrylate) by ester interchange. The nuclear magnetic resonance spectrum of the crystalline poly(tert-butyl acrylate) showed no evidence of band splitting and the viscosity-slope constant, k′, was the same for crystallizable and noncrystallizable polymer.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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