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  • 21
    ISSN: 1573-4803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The effect of vapor grown carbon fiber (VGCF) on the morphology, crystallization and melting behaviors of isotactic polypropylene (iPP)/high density polyethylene (HDPE) blend have been studied by means of Scanning Electron Microscopy (SEM) and Differential Scanning Calorimeter (DSC). It is found that the addition of VGCF results in a dramatic change in the morphology of iPP/HDPE blends. The crystallization peak temperature and melting point of iPP are not altered significantly by the blending. However, the degrees of crystallinity of iPP in the blends are reduced. Compared with the unfilled blends, the crystallization peak temperatures of iPP increase dramatically for the composites. The isothermal crystallization behavior of iPP is further investigated. The analysis of the crystallization half time shows that the crystallization rate of iPP is reduced by the presence of HDPE melt, and is enhanced by carbon fibers. For the unfilled blends in which iPP is the major component, the Avrami exponent closes to 3, independent of the HDPE content. However, for the composites, the Avrami exponent varies with the composition in a rather complex manner. An explanation based on heterogeneous and homogeneous nucleation is supposed. The sharp changes in the crystallization and melting behaviors for the composites containing 30–35wt% HDPE correspond to the sudden change in the morphology of the two phases. It is supported by the observation of SEM and the electrical measurement.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 31 (1996), S. 281-289 
    ISSN: 1573-4803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The physical properties of carbon black-filled rubbers are affected mainly by the distribution of filler, carbon black properties and polymer-filler interactions. A number of experimental methods and approaches for characterization of the dispersion state of filler in rubber-carbon black composites and an investigation of polymer-filler interactions are reviewed. The dispersion state characterization, electrical conductivity measurements, bound rubber evaluations, mechanical properties measurements, carbon black surface properties study, small angle X-ray scattering (SAXS) and nuclear magnetic resonance (NMR) spectroscopy are among the most important ones.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 39 (1998), S. 331-340 
    ISSN: 0021-9304
    Schlagwort(e): cytotoxicity evaluation ; colony formation method ; metallic biomaterials ; metal salts ; murine fibroblasts ; osteoblastic cells ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Metallic biomaterials are generally used for replacement of structural components of the human body such as bones, joints, and tooth roots. When they are implanted inside a body, metallic biomaterials may corrode and/or wear, releasing metal ions and debris which may have toxic effects on tissues and organs. Since it is important for biomaterials to have no toxicity against a living body, a systematic and quantitative evaluation of the cytotoxicity of metallic elements is required for the development of new metallic biomaterials with superior biocompatibility. In this study, the cytotoxicity of 43 metal salts were evaluated by the colony formation method using two kinds of cultured cells. The effects of the difference in valence numbers of metallic elements in the salts on cytotoxicity were examined. The cytotoxicity of the salts of metallic elements' oxo acids was also investigated. As a result, the intensity of metal salts' cytotoxicity tends to be quite similar between MC3T3-E1 and L929 (the correlation coefficient of metal salts' IC50s is 0.82). The intensity of metal salts' cytotoxicity depends on the kinds of metallic elements, their chemical states, and concentrations. The IC50 of the highest toxic salt is 1.36 × 10-6 mol L-1, which differs four orders of magnitude from the IC50 of the lowest toxic salt. K2Cr2O7, CdCl2, VCl3, AgNO3, HgCl2, SbCl3, BeSO4, and InCl3 are high toxic salts in which IC50s are smaller then 10-5 mol L-1 for both or either of the cell lines. HgCl, Tl(NO3)3, GaCl3, CuCl2, MnCl2, CoCl2, ZnCl2, NiCl2, SnCl2, IrCl4, TlNO3, CuCl, RhCl3, Pb(NO3)2, Cr(NO3)3 and Bi(NO3)3 are relatively high toxic salts in which IC50s are smaller than 10-4 mol L-1 for both or either cell lines. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 331-340, 1998.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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