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  • 1
    Electronic Resource
    Electronic Resource
    Morphology of banded spherulites in poly(ε-caprolactone)/poly(styrene-ran-acrylonitrile) blends (1997)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 48 (1997), S. 354-362 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The occurrence of banded spherulites in blends of poly(ε-caprolactone) with poly(styrene-ran-acrylonitrile) is studied by means of optical-, scanning electron-, environmental scanning electron-, and atomic force-microscopy as well as smallangle X-ray scattering. The measurements reveal that lamellae are confined in fibrils that bend periodically from the center of spherulites in a radial direction. The fibrils show also a regular spacing in the lateral direction. Single bent lamellae can be observed by atomic force microscopy after permanganic etching. The enrichment of amorphous material near to the growth front of the spherulites can be directly observed by polarized light microscopy after temperature jump experiments. The excluded amorphous material on the surface of the growing spherulites has the shape of droplets. This might be the main reason for the initiation of the bending process because the result is a non-uniform stress distribution acting on the growing lamellae at the interface between spherulites and the surrounding melt. The amorphous material of the blends can be found in three areas as observed by small-angle X-ray scattering experiments and microscopical methods: (i) between the lamellae, (ii) excluded from the interlamellar region but within the spherulite, and (iii) for high contents of non-crystallizable material, it can be excluded from the spherulite. The banding periodicity of spherulites as a function of the crystallization temperature can be described in terms of two models, based either (i) on the inherent twisting of lamellae perpendicular to the axis of a screw dislocation or (ii) on the dependence of the diffusion of amorphous material away from the growth front of lamellae and the temperature dependence of the rate of crystallization. Both models fail at very low supercoolings near to temperatures where the banding disappears completely.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1997.010480902
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of equation-of-state parameters and the description of PVT-data (1996)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 47 (1996), S. 520-524 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: For three different equation-of-state theories the characteristic parameters of two polymers were calculated, and the ability of the theories to describe PVT-data using these parameters was investigated. The comparison between the different theories shows that, concerning the description of PVT-data, the modified cell model of Dee and Walsh is not only superior to the theory of Flory, Orvoll and Vrij and that of Sanchez and Lacombe as reported before, but also to the theory of Simha and Somecynsky and the open cell model of Zhong, Wang and Lu. Finally, simple formulae are given to calculate the characteristic parameters of the latter two theories from those of the theory of Flory, Orwoll and Vrij.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1996.010471108
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  • 3
    Electronic Resource
    Electronic Resource
    Evaluation of equation-of-state parameters from PVT data (1995)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 46 (1995), S. 312-318 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The characteristic parameters for three different equation-of-state (EOS) theories have been determined for polystyrene and low-molecular weight polyisoprene using pressure-volume-temperature (PVT) data. Basically two procedures for the calculation of characteristic parameters were applied. The characteristic parameters were calculated, firstly, from coefficients of expansion, compressibilities and densities, and secondly, by fitting the corresponding EOS to PVT data minimizing the sum of the squares of the differences between experimental and calculated pressures. The characteristic parameters obtained by the two methods are compared with regard to their ability to describe PVT data. A comparison of the three different EOS theories reveals that, for describing polymeric liquids, the modified cell model of Dee and Walsh is superior to the theory of Flory, Orwoll and Vrij as well as to the lattice fluid theory of Sanchez and Lacombe. Finally, formulae are given to convert the characteristic parameters from one theory into those of another.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1995.010460405
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  • 4
    Electronic Resource
    Electronic Resource
    A novel method of preparing of glass capillary columns: Low-temperature plasma etching and polymerization (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 400-404 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Low temperature plasma etching ; Polymer film on the inner surface from organosilicone monomer ; Flexibility of this new method discussed ; Discharge chamber described ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel method is described for the preparation of stable glass capillary columns (glass open tubular columns), including the etching and formation of a polymer film on the inner glass capillary surfaces. The approach used here is based on low-temperature plasma etching and polymerization. Under the influence of a field of radio frequency discharge, low pressure gases of fluoric compounds, introduced into the glass capillary tube, generate excited fluorine radicals which etch the inner surface. The plasma of organosilicone monomer in the glass capillary yields a uniform polymerized film on the inner surface. The resultant material functions as a good stationary phase for glass capillary gas chromatography (GC2). The inner surfaces treated with such a plasma, can be studied by means of a scanning electron microscope (SEM). The flexibility of this method permits the use of various stationary phases and surface modification.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240020706
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  • 5
    Electronic Resource
    Electronic Resource
    Analysis of crude drugs by pyrolysis gas chromatography (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 360-361 
    Details
    ISSN: 0935-6304
    Keywords: Pyrolysis gas chromatography ; Fused silica open tubular column ; Crude drugs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240080708
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  • 6
    Electronic Resource
    Electronic Resource
    Rapid characterization of spices and herbs by direct heating sample introduction using a curie-point pyrolyzer (1988)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 347-350 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240110412
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of the surface geometry of smooth and porous-coated titanium alloy on the orientation of fibroblasts in vitro (1987)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 21 (1987), S. 107-126 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The migration and orientation of human gingival fibroblasts in relation to the rim of smooth-surfaced and porous-coated titanium discs placed on multilayers in vitro was investigated. Samples were examined after 6 h, 24 h, 3 days, and 7 days of culture using phase-contrast and scanning electron microscopy. The cells migrated from the multilayer onto the smooth-surfaced discs forming bridges between them, and orientated along parallel circumferential grooves in the rim of the discs. This resulted in the cellular bridges orientating at an acute angle to the rim of the disc, and adjacent cells in the multilayer orientating parallel to the rim. Cellular bridges were also formed between the porous-coated discs and the multilayer but, because the cells that migrated onto, and between, the spheres of the porous-coat showed no preferred orientation, the bridges retained their orientation at right angles to the surface of the rim. This in turn resulted in the cells of the adjacent multilayer becoming similarly orientated. These observations suggest that the geometrical configuration of the surface of implants could influence whether a capsule or an orientated fibrous attachment is developed in relation to implants in vivo.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820210114
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