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  • 1
    Electronic Resource
    Electronic Resource
    Evaluation of the kinetic parameters for styrene polymerization and their chain length dependence by kinetic simulation and pulsed laser photolysis (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 1691-1705 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Pulsed laser photolysis (PLP) has been employed to determine propagation rate constants kp for styrene polymerization in benzene over a wider temperature range (20-80°C) than previously converd. It is proposed that a small chain length dependence of kp (overall) may, in part, be a consequence of a marked chain length dependence of kp for the first few propagation steps [i.e. kp(1) 〉 kp(2) 〈 kp(3) ≥ kp(≥4)]. The propagation rate constant for styrene polymerization is given by the expression: In kp = 16,09 - 28950/(RT) (overall) or In kp = 16,47 - 30084/(RT) (chain length ≥ 4). Kinetic simulation has been applied both as an aid in data analysis and to demonstrate the reliability of the PLP technique for evaluation of propagation rate constants (kp) in radical polymerization. This has been achieved by examining the sensitivity of the molecular weight distribution of polymers formed in PLP experiments to the values of the kinetic parameters associated with polymerization and their chain length dependence. The termination rate constants (kt = kc + kd) and the ratio of combination to disproportionation (kc: kd) markedly affect the molecular weight distribution of polymer formed in PLP experiments. The prospects for evaluating the values of kt, its chain length dependence and kc : kd by direct analysis of the molecular weight distribution are discussed in the light of these results.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021940617
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  • 2
    Electronic Resource
    Electronic Resource
    Crystallographic studies of nylon 4. I. Determination of the crystal structure of the α polymorph of nylon 4Paper presented at the First Middle Atlantic Regional Meeting of the American Chemical Society, Philadelphia, February 4, 1966. (1966)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 4 (1966), S. 899-911 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal structure of the α polymorph of nylon 4 has been determined from the x-ray diffraction patterns of uniaxially oriented monofilaments. In general the crystal structure of α nylon 4 is similar to that of α nylon 6. The unit cell is monoclinic with the following dimensions: a = 9.29 ± 0.05 A., b = 12.24 ± 0.05 A., c = 7.97 ± 0.05 A., and β = 114.5 ± 1.0°. There are eight monomeric units in the unit cell. The theoretical density is 1.37 g./cc. and the observed density 1.25 g./cc. The space group is P21. The nylon 4 chains are of the extended planar zigzag type, with the plane of the zigzag approximately parallel to the a axis of the unit cell. Along the a axis, every other chain is inverted - an antiparallel arrangement of chains - thus permitting complete hydrogen bonding and the formation of sheets of nylon 4 chains. Along the c axis of the unit cell, the second sheet is displaced by3/10 of the b axis, thus leading to a staggered arrangement of sheets. The sheets are held in place by van der Waals forces.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1966.160040606
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis of regiospecifically meta-substituted poly(phenylacetylene)s and some of their electrical properties (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 989-997 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses, characterizations, and electrical properties of four regiospecifically substituted poly(phenylacetylene)s are described. Tungsten(VI) chloride/tetra-n-butyltin (WCl6/n-Bu4Sn) catalyst system (Higashimura-Masuda, H.-M. catalyst) was used to polymerize 3-bromo-, 3-chloro-, 3-trimethylsilyl-, and 3-trimethylstannylphenylacetylenes in order to obtain high-molecular-weight and soluble materials. Characterizations of these polymers were done by IR and UV spectroscopic methods, GPC, DSC, and elemental analysis. The electrical conductivities of the polymers were measured on the surface of pressed pellets by a four-point probe.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080270322
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  • 4
    Electronic Resource
    Electronic Resource
    Einsatz des Wirbelstromprüfverfahrens zur zerstörungsfreien Bestimmung der Angriffstiefe von Korrosionsschäden an Flugzeug Tragflächenbeplankungen (1995)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 46 (1995), S. 473-480 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Application of eddy-current method for nondestructive determination of corrosion attack depth at aircraft wing skinsA NDI test system for the determination of the depth of corrosion attack in the form of shallow pit formation and pitting is presented. The system is based on the eddy-current method, whereby the signals of a specially developed probe are converted to an image representation, which can he evaluated quantitatively at a PC-screen. The described test system was developed for the field of in-service inspection of aeroplanes. As a first practical operation, the system was tested in co-operation with Daimler-Benz Aerospace at TORNADO aeroplanes. All the described results can be transferred to other test situations with comparable damage mechanisms. Because of the Skin-effect of the eddy current, this method is limited to surface-near areas however. If the test object comes as metal sheets, depth evaluation of corrosion attack on the hidden surface is also possible (even in multi-layered structures).
    Notes: Vorgesellt wind ein Prüfsystem zur zerstörungsfreien Bestimmung der Angriffstiefe von Korrosionsschäden vom Typ Muldenkorrosion und Lochfraß. Grundlage hierfür ist die Wirbelstromprüfung, wobei Meßsignale einer speziellen Tastsonde zu bildhaften Informationen zusammengetragen werden, die anschließend an einem PC-Bildschirm quantitativ ausgewertet werden können. Das beschriebene Prüfsystem wurde für den Bereich der Betriebsüberwachung von Flugzeugen entwickelt. Als erster praktischer Einsatz wurde das System in Zusammenarbeit mit Daimler-Benz Aerospace an Flugzeugen des Typs Tornado eingesetzt. Allgemein lassen rich die erreichten Ergebnisse auf andere Prüfsituationen mit vergleichbaren Schädigungsmechanismen übertragen. Aufgrund des Skin-Effekts der Wirbelströme muß jedoch die Aussage auf den oberflächennahen Bereich beschränkt bleiben. Liegt das Prüfteil in Form von Blechen (auch geschichtet) vor, so ist eine Aussage für die zur Prüfsonde abgewandten, verdeckten Oberfläche(n) möglich.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19950460805
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  • 5
    Electronic Resource
    Electronic Resource
    Size-exclusion chromatography with two-angle laser light-scattering (SEC-TALLS) of high molecular weight and branched polymers (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 56 (1995), S. 65-72 
    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 accuracy and precision of results obtained from light-scattering detection at two angles (TALLS) for size-exclusion chromatography (SEC) are examined for linear narrow molecular weight distribution polystyrenes between 1,290,000 and 20,000,000 MW and for branched polyesters. The ratio of light-scattering intensities at 15° and 90° is used to calculate weight-average molecular weight, M̄w, and an average root-mean-square radius, r̄gu, equivalent to the z-average radius. A shape for the polymer molecule is assumed and an analytical relationship for the particle-scattering function is required. It is shown that analysis of the data using the particle-scattering function for a random coil is valid for both high molecular weight, linear polystyrenes and long-chain branched polyesters. The radius, r̄gu, is determined with high precision by using the ratio of light-scattering signals, which is insensitive to errors in sample concentration and changes in the eluent flow rate. The correct average radius for the whole polymer is obtained despite using low-efficiency, large-particle diameter SEC columns; however, axial dispersion significantly affects molecular weights and radii calculated at each retention volume that can limit the utility of plots used to deduce polymer conformation. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070560109
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  • 6
    Electronic Resource
    Electronic Resource
    Number-average molecular weight and functionality of poly(tetramethylene glycol) by multidetector SEC (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 56 (1995), S. 211-220 
    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: Multidetector size exclusion chromatography (SEC) is used to simultaneously determine molecular weight and number of reactive end groups per chain (functionality) of poly(tetramethylene glycol)s. Hydroxyl groups are first quantitatively derivatized with phenyl isocyanate, providing an end-group-selective UV-absorbing tag. The number of end groups per chain is then determined from the SEC chromatogram using a UV detector. Molecular weight at each retention volume and the number-average molecular weight of the whole polymer are calculated by four methods involving (1) a concentration detector and a narrow standard log M calibration curve, (2) the UV detector and a narrow standard log M calibration, (3) a viscometry detector and a universal calibration curve, and (4) combined differential viscometry and concentration detectors using a universal calibration curve. The multidetector experiment provides a unique opportunity to assess the accuracy and limitations of each approach on low-molecular-weight polymers. In particular, the effect of end groups on the concentration detector response and the application of universal calibration principles at small molecular sizes are important factors. It is shown that the concentration response can be corrected by a simple relationship between detector response and reciprocal molecular weight. Also, the quality of calibration curves is critical to the calculation of accurate molecular weight. In general, log M calibration curves provide superior results to universal calibration methods. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070560211
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  • 7
    Electronic Resource
    Electronic Resource
    Crystallographic studies of nylon 4. II. On the β and δ polymorphs of nylon 4Paper presented at the First Middle Atlantic Regional Meeting of the American Chemical Society in Philadelphia, February 4, 1966. (1966)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 4 (1966), S. 913-922 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In addition to the α polymorph, two crystalline forms of nylon 4, the β and δ polymorphs, have been observed and studied.The β polymorph of nylon 4, which has not been found in a pure condition, appears to be similar to the β polymorph of nylon 6. The extended planar zigzag conformation of chains, found in the α polymorph, is present also in the β polymorph. Three models have been proposed to explain the observed data. In model 1, the staggered shear of van der Waals bonded sheets found in the α polymorph is abandoned; in model 2, the sheets are displaced by 1/2 the b axis, and in model 3 the chains are arranged in a parallel array. The β polymorph is converted to the α form in air upon heating for 11 min. at 227°C. and upon immersion in water for 2 hr. Models 1 and 2 would be converted to the α polymorph by a slippage of the van der Waals bonded sheets while the conversion from model 3 would involve a rupture of hydrogen bonds, a rotation of the chains through 90°, and the reformation of hydrogen bonds. The δ polymorph is formed by rapidly quenching extruded nylon 4 against chilled rolls. It is a metastable form which has only been observed in an unoriented condition. Upon orientation it is completely converted to the α polymorph. In addition to this, its conversion to the α form occurs under conditions similar to the β-α transition. The observed diffraction pattern can be indexed on the basis of a hexagonal packing of chains. High-temperature x-ray diffraction studies of the α polymorph suggest that the δ form, or a structure similar to it, is the high-temperature form of nylon 4.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1966.160040607
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  • 8
    Electronic Resource
    Electronic Resource
    Einsatz eines Fluoreszenzsensors zur Messung der NAD(P)H-abhängigen Kulturfluoreszenz immobilisierter Zellsysteme (1987)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 59 (1987), S. 600-601 
    Details
    ISSN: 0009-286X
    Keywords: Clostridium acetobutylicum ; immobilisierte Zellen ; On-line- und In-situ-Messung ; NAD(P)H-abhängige Kulturfluoreszenz ; Mikrofluorometer ; zellinterne Parameter ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330590718
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  • 9
    Electronic Resource
    Electronic Resource
    Rückgewinnung von Metallen mit Hilfe trägergestützter FlüssigmembranenKurzfassung eines auf der GVC-Dezembertagung am 6. Dez. 1985 in Aachen gehaltenen Vortrages von K. Schneider. (1986)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 58 (1986), S. 800-802 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330581007
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  • 10
    Electronic Resource
    Electronic Resource
    Directions for improvement of substitute heart valves: National Heart, Lung, and Blood Institute's working group report on heart valves (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 38 (1997), S. 263-266 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: No abstract.
    Type of Medium: Electronic Resource
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