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  • 1
    Electronic Resource
    Electronic Resource
    The deformation behaviour of polyethylene shish-kebabs produced by stirring-induced crystallization (1984)
    Springer
    Colloid & polymer science 262 (1984), S. 521-525 
    Details
    ISSN: 1435-1536
    Keywords: polyethylene ; shish-kebabs ; stirring-induced crystallization ; deformation ; scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polyethylene mats of shish-kebab fibrils were prepared from solution by stirring-induced crystallization, and subjected to deformation. A morphological study by scanning electron microscopy showed that the elementary shish-kebabs are elongated during drawing. For low draw ratios, the average distance between the lamellae on the fibrils increases proportionally to the draw ratio. The invariance of the fibril diameter upon drawing indicates a transformation of lamellar into fibrillar material. The molecular topology which underlies this deformation mode is discussed and related to the crystallization process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01451515
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Gas-Liquid mass transfer in fixed-bed reactors with cocurrent downflow operating in the pulsing flow regime (1984)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 30 (1984), S. 393-401 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Liquid-side mass transfer coefficients were measured for cocurrent two-phase downflow in 5 and 10 cm diameter columns pakced with 2.5 and 4 mm Raschig rings. Experiments were specifically carried out in the pulsing flow regime. The mass transfer coefficients were determined via absorption of CO2 into buffer solutions with the advantage of a high absorbing capacity. Thus columns of 1 m length could be used. Relations are proposed based on the hydrodynamic phenomena observed in pulsing flow. From these relations a correlation for kL is found in terms of flow rates and packing characteristics that satisfies the experimental data.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690300307
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The plastic deformation of ultra-high molecular weight polyethylene (1985)
    Springer
    Journal of materials science 20 (1985), S. 1556-1570 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Gel-spun filaments of different initial morphologies have been subjected to controlled drawing at elevated temperatures. The drawn samples have been examined by high-resolution scanning electron microscopy. The deformation mechanism at temperatures up to 120° C is very similar to crazing, especially in the case of unoriented gel-spun filaments. Filaments exhibiting a shish-kebab morphology offer the opportunity of examining the deformation of elementary fibrils in a quantitative way. The transformation of individual lamellae into fibrils is the initial deformation mode, which is followed by slip of fibrils at a later stage. This is concluded from a comparison of experimental data and model calculations of the maximum draw ratio. Drawing at 144° C results in the formation of globular aggregates of lamellae, with a characteristic long period of 40 nm. This long period persists until all the globules have been converted, by micronecking, into aggregate fibrils of extended-chain character. On a molecular scale, the various processes can be described as the temperature-dependent flow behaviour of an entanglement network.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00555260
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of the nature of the polymer backbone on the stability and the analytical response of polymer-modified electrodes (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 333-339 
    Details
    ISSN: 1040-0397
    Keywords: Modified electrode ; Redox polymer ; Sensor ; Flow injection analysis ; Iron ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis, characterization, and sensor application of the novel redox polymer [Os(bipy)2(PS)7.5(DMAP)2.5Cl]Cl, where bipy = 2,2′-bipyridyl, PS = polystyrene, and DMAP = poly[4-(N-methyl-N-p-vinylbenzylamino) pyridine], are described. The charge transport properties of electrodes modified with the redox material are investigated using cyclic voltammetry and chronoamperometry. The modified electrode behaves as an efficient electrocatalyst for the outer-sphere reduction of FeIII, with the cross-exchange reaction occurring at the surface of the polymer (Sk″) at concentrations less than 1.0 × 10-3 mol dm-3 FeIII, with a change over to the Ste, kinetic regime at higher substrate concentrations. Direct agreement was observed between the kinetic behavior at rotating disk electrodes and in thin-layer flow cells. Application of the modified electrodes for the determination of iron in pharmaceutical formulations and the long term stability of the electrodes are investigated. The results obtained are compared with those reported for the analogous metallopolymer [Os(bipy)2(PVP)10Cl]Cl, where PVP is poly-4-vinylpyridine.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140070406
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    Paper (German National Licenses)
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