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  • 1
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Wurtz-type coupling of a number of representative classes of substituted dichlorosilane monomers was investigated in considerable detail. Low temperature polymerization techniques, including ultrasonic activation, were also studied. Similarly, the effect of dipolar additives on the polymerization process was examined. The conclusions drawn from these studies provide some insight into the selection of useful polymerization conditions for the conversion of various monomer types into linear high polymers.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 107-112 
    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: A simple 13C-NMR method for the quantitative determination of polyflavonoid tannin characteristics was developed. The system is effective for use on concentrated (25-50%) solutions of natural and modified tannins. It allows the determination of the average degree of polymerization (DPn) of the polyflavonoid, resorcinol vs. phloroglucinol proportion of the A-ring and catechol vs. pyrogallol proportion of the B-ring. The results obtained are consistent with existing data determined by other techniques. The method was also tried with tannin extract that was modified to form thermosetting adhesive intermediates, and with tannin modified by sulfonation, a common commercial modification for these materials. The results were again consistent with what was expected. The method affords the possibility to follow by a simple technique the variations in DPn and MM̄n (number-average molecular weight) induced by chemical modifications of polyflavonoid tannin extracts and thus to correlate them with relevant structural modifications affecting these parameters. The method is not capable of distinguishing the relative proportions of the four important flavonoid units present in commercial polymeric tannin extract. It can only distinguish the relative proportions of (i) (procyanidins + prodelphinidins) vs. (profisetinidins + prorobinetinidins) and (ii) (prorobinetinidins + prodelphinidins) vs. (profisetinidins + procyanidins). © 1995 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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  • 3
    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 crystal orientation distribution in injection-molded bars made from several polypropylene compounds has been investigated using pole figure analysis. The fillers used were glass fibers, chalk, and talc, and some compounds contained one filler and others contained glass fibers plus one or both of the others. All compounds showed strong orientation in the skin with the b-axis of the monoclinic crystals lying preferentially normal to the flow direction and in many cases parallel to the normal to the bar face. This normal direction orientation was very strong in compounds containing talc and is probably caused by crystals forming with their (010) planes on the talc platelet faces, which align themselves parallel to the mold face. Strong orientation persists into the interior of the moldings containing talc, whereas in the other compounds, the orientation at intermediate depths is much less pronounced than in the skin. © 1992 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zirconium hydrocarbyl catalysts react with nylon and poly(ethylene terephthalate) (PET) fibers to produce a supported species which may be used to polymerize a sheath of polyethylene around the fiber. Very high catalyst activities have been achieved over very short reaction periods on PET spinning threadlines. It is also possible to use these reagents to produce strongly adhered oxide and sulfide surface coatings. Infrared evidence is given for a mechanism in the case of reaction between catalyst and PET.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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