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  • 1
    Electronic Resource
    Electronic Resource
    Relationships between mechanical properties and microhardness of polyethylenes (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 172 (1989), S. 25-35 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Werte des Elastizitätsmoduls (E) und der Fließspannung (Y) und die Gestalt der Spannungs-Dehnungskurven wurden mit der Mikrohärte (MH) dieser Materialien verknüpft, unter Beachtung der Rolle, die die kristallinen, amorphen und Phasengrenzbereiche bei der Verformung der kristallinen Polymeren spielen. Es wurden lineare Beziehungen zwischen der Mikrohärte und dem Kristallinitätsgrad (1-λ)d und zwischen den Logarithmen von E und MH gefunden. Die Änderungen der Parameter 100 Y/E und σmin/Y (σmin ist das relative Minimum der Nominalspannung für Dehnungen oberhalb der Streckgrenze) als Funktion von (1-λ)d folgen unterschiedlichen Trends für lineare und verzweigte Polyethylene. Außerdem zeigte sich, daß das Verhältnis MH/Y für diese Materialien kleiner als drei ist, wobei dieser theoretische Wert (Taborgleichung) nur bei den höchsten Kristallinitätsgraden angenähert wird.
    Notes: The values of the elastic modulus (E) and the yield stress (Y) and the shape of the strain-stress curves of different polyethylenes have been related to the microhardness (MH) of these materials, considering the roles that the crystalline, amorphous, and interfacial regions play in the deformation of semicrystalline polymers. Linear relations between microhardness and degree of crystallinity, (1 - λ)d, and between the logarithms of E and MH have been found. The variations of the parameters 100Y/E and σmin/Y (σmin is the relative minimum value of the nominal stress for elongations above the yield point) as a function of (1-λ)d follow different trends for linear and branched polyethylenes. Moreover, it has been found that the ratio MH/Y is smaller than three for these materials, approaching this theoretical value (Tabor relation) only for the highest crystallinity levels.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051720103
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  • 2
    Electronic Resource
    Electronic Resource
    Acceleration of the rate of alkaline ester hydrolysis by linear amphiphilic ionenes (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 20 (1982), S. 433-437 
    Details
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.130200806
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  • 3
    Electronic Resource
    Electronic Resource
    Diffusion coefficients of segmentally flexible macromolecules with two sphrical subunits (1985)
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 2145-2164 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The translational and rotational diffusion coefficients have been calculated for a simple, segmentally flexible model: the hinged dumbbell (HD). In the HD, two spherical subunits are attached to an universal joint by means of frictionless connectors. In addition to the case in which hydrodynamic interactions are neglected (NI), we have also considered two more cases, including hydrodynamic interaction by means of the Kirkwood-Riseman approximate treatment (KR) and using accurate procedure based in the series expansions for the two-sphere diffusion tensor (SE). Expressions for the friction coefficients of the HD are given for the three cases, and the diffusion coefficients are evaluted inverting the 9 × 9 resistance matrix, for two HDs with different dimensions. The KR treatment, which includes a contribution from the finite volume of the subunits, is shown to be an excellent approximation to the more rigorous procedure. In the NI case for rotation, the various coefficients present different deviations with respect to the SE results. A rough estimate of the errors of the NI relaxation times indicates that they may be smaller than 15% for a HD with identical beads. However, the influence of hydrodynamic interaction should be more important for the rotational diffusivity of a small sphere attached to a larger one. The error of the NI result for the translational diffusion coefficient is of about 25% for the two HDs.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360241110
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  • 4
    Electronic Resource
    Electronic Resource
    Application of chitosan to cobalt recovery: Evaluation by factorial design of experiments (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 2107-2115 
    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: A natural polymer in a commercially available form (chitosan) has been tested using a factorial design of experiments for its application to cobalt recovery either in hydrometallurgy and in analytical separations. A simple mechanically stirred system has been used, evaluating the influence of the contact time, iron(II), cobalt (II), chitosan concentration, salinity, and pH in the separation. The pH value has a dramatic influence on the metal recovery from a negligible amount of metals at pH = 1.0 to a quantitative sorption at pH = 3.0. Linear relationships between sorbed metal and the variables have been determined at constant pH value and a quantitative evaluation of the metal recovery at different pH values can be performed using the maximum sorption capacity of the chitosan (a0) and the selectivity for both metals. The obtained results allow the evaluation of the recovery of metals using chitosan as solid phase.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330622
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of iron oxides on the thermal degradation of natural rubber from Manihot glaziovii (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 1371-1376 
    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 effect of iron oxides particles mixed in natural rubber (NR) or aged natural rubber (ANR) from Manihot glaziovii were investigated. IR spectroscopy showed that α-Fe2O3 inhibits or retards the thermal degradation (200°C) of ANR, but it does not inhibit or retard the thermal degradation of NR. A retardation effect is observed using iron (III) oxide in both ANR and NR. Using both oxides, longer autoxidation induction periods of ANR and NR are observed (150°C). The periods were extended for a higher content of rubber hydroperoxide concentration. The inhibition or retardation of autoxidation using Fe3O4 in both ANR and NR is not evident. We suggest an interaction between hydroxyl groups of hydroperoxide, mainly present in aged natural rubber, and the iron oxide surface.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440808
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  • 6
    Electronic Resource
    Electronic Resource
    Polymer retention mechanisms in GPC on active gels, 3Part 2: Cf. 6.. Poly(dimethylsiloxane) and poly(methyl methacrylate)Partially presented at the “International Liquid Chromatography Symposium IV”, Strasbourg, October 1979. (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 1525-1532 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Elution curves on spherosil gels in pure and mixed eluents of poly(dimethylsiloxane), PDMS, and poly(methyl methacrylate), PMMA, as well as those of polystyrene, PS, just for comparison, have been determined. In a general way, PDMS elution volumers fit to those of PS, whereas PMMA elution curves shift to higher retention volumes. The differences in retention volumes between the different polymeric solutes have been interpreted in terms of differences in polymer-gel and polymer-solvent interactions. Hydrogen-bonding seems to be the main contribution to solute-substrate interactions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820523
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  • 7
    Electronic Resource
    Electronic Resource
    Polymer retention mechanism in GPC on active gels, 1. Polystyrene in pure and mixed eluents (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 1961-1974 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The elution behaviour of polystyrene (PS) on spherosil X0A 200 gel in twenty one eluents and its dependence on solvent goodness, as defined by the α exponent of the Mark-Houwink equation, and solvent strength, ∊0, have been studied. The interstitial volume, Vo, seems to depend solely on solvent goodness, being minimum for good solvents and maximum for solvent mixtures at Θ composition or close to it. By application of a network-limited partition and adsorption mechanism, average pore radii of the gel, r, have been obtained. For ∊0 〉 0,45 a linear dependence with negative slope between r and ∊0 exists, whereas for ∊0 〈 0,45 r values seem to display a joint dependence on ∊0 and α·∊0 α = 0,17 is the limit for obtaining experimental PS elution curves, below that value the polymer being not recovered. A coefficient f, which allows the evaluation of relative distribution coefficients (Kp) is introduced and its numerical values determined for all the eluent systems. The f dependence on ∊0 and αis similar to that followed by r. At high ∊0 values partion effects will be mainly responsible for Kp values. However, at low ∊0 values, besides partition, adsorption effects contribute to the increase of Kp values.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800811
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  • 8
    Electronic Resource
    Electronic Resource
    Electrochemical behavior of triazolobenzodiazepine derivativesDedicated to the memory of Professor G. J. Patriarche. (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 1040-1044 
    Details
    ISSN: 1040-0397
    Keywords: Triazolobenzodiazepine ; Voltammetry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical behavior of two novel triazolobenzodiazepines (adinazolam and U43.465F) has been studied in the pH range 3 to 13.5. Both compounds are reduced on the dropping mercury electrode and yield one reduction wave attributed to the azomethine group. The two-electron transfer is polarographically reversible. However, the transfer is followed by a fast conversion of the elearolysis product by a chemical reaction with an irreversible global process. A weak adsorption of the reactant has been observed under certain conditions. Quantitative analysis has been performed, showing that adinazolam and U43,465F can be determined up to 1.1 × 10-6M using differential pulse polarography.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140061121
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  • 9
    Electronic Resource
    Electronic Resource
    Vanadium(V) determination through a catalytic polarographic method (1991)
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 715-719 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for determining trace level of vanadium(V) has been developed. The reaction is the polarographic reduction of the bromate, catalyzed by this metal ion, in the presence of cupferron, in acetic-acetate medium. The peak current obtained is proportional to the vanadium(V) concentration between 2.10-8 and 3.10-7 M, with a detection limit of 6.10-9 M. The procedure is very selective and has been successfully applied to a certified steel sample after extraction of iron wit ethyl ether.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140030720
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  • 10
    Electronic Resource
    Electronic Resource
    Elimination of zinc/copper intermetallic interference in the determination of zinc in wastewaters and seawater by potentiometric stripping analysis (1993)
    Weinheim : Wiley-Blackwell
    Electroanalysis 5 (1993), S. 685-689 
    Details
    ISSN: 1040-0397
    Keywords: Potentiometric stripping analysis ; Zinc analysis ; Zinc/copper intermetallic interference ; Short enrichment times ; Zinc speciation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new approach to the elimination of Zn/Cu intermetallic interference in the determination of zinc by potentiometric stripping analysis is described. The method is based on the use of several enrichment/ stripping cycles, with each cycle using an enrichment time of 10 seconds or less and the stripping signal from each cycle being added to give the total stripping signal. The additive method compares favorably with the traditional “third element” approach based on the use of gallium, and it is demonstrated that, for an industrial sample containing oil and grease, the additive method has significant advantages over the gallium method. The advantages of potentiometric stripping analysis in monitoring zinc in industrial wastes and the applicability of the technique to zinc speciation studies are described.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140050810
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