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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 268 (1990), S. 528-535 
    ISSN: 1435-1536
    Schlagwort(e): Polypropylene/polystyreneblends ; nucleation ; isothermalcrystallization ; spheruliticgrowth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Crystallization kinetic parameters, such as spherulitic growth rates, nucleation densities, and Avrami-exponents, have been determined by optical microscopy for isotactic polypropylene blended with atactic polystyrene. It is found that the crystallization of iPP is strongly influenced by the presence of polystyrene. With increasing PS concentration in the blend, the nucleation densities decrease, while the spherulitic growth rates as well as the positions of thermal peaks, measured by DSC, remain independent of sample composition. Due to the formation of interfaces as a consequence of increasing dispersion of polystyrene the nucleation changes from preferentially thermal to athermal.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 271 (1993), S. 824-833 
    ISSN: 1435-1536
    Schlagwort(e): Polypropylene ; EPDM ; interphase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The interaction of isotactic polypropylene with ethylene propylene diene terpolymer in their blends has been investigated by use of differential scanning calorimetry, dynamic mechanical analysis, wide- and small-angle x-ray scattering, and by investigating the nucleation and kinetics of crystallization of the iPP component under the polarization microscope. It is found, that the dispersion of the EPDM component in the iPP matrix is dependent on blend composition and is maximal at 10% EPDM content. An interface layer between the two components is formed by migration of iPP molecules into the EPDM phase. A model for this interface is proposed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 276 (1998), S. 747-749 
    ISSN: 1435-1536
    Schlagwort(e): Key words Polypropylene ; nucleation ; isothermal crystallization ; molecular fractionation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The nucleation frequency of isotactic polypropylene shows for certain molecular weight distributions during isothermal crystallization a “stepwise” development of the nuclei as a function of time. The resulting curve can be fitted by a superposition of exponential functions assuming a separate nucleation density for each nucleation step. The multimodal nucleation is discussed as a consequence of molecular fractionation effects during crystallization.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 31 (1993), S. 585-592 
    ISSN: 1741-0444
    Schlagwort(e): Air Flow ; Human ; Nasal cavity ; Nose ; Turbinate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The nasal cavity is the main passage for air flow between the ambient atmosphere and the lungs. A preliminary requisite for any investigation of the mechanisms of each of its main physiological functions, such as filtration, air-conditioning and olfaction, is a basic knowledge of the air-flow pattern in this cavity. However, its complex three-dimensional structure and inaccessibility has traditionally prevented a detailed examination of internalin vivo orin vitro airflow patterns. To gain more insight into the flow pattern in inaccessible regions of the nasal cavity we have conducted a mathematical simulation of asymmetric airflow patterns through the nose. Development of a nose-like model, which resembles the complex structure of the nasal cavity, has allowed for a detailed analysis of various boundary conditions and structural parameters. The coronal and sagittal cross-sections of the cavity were modeled as trapezoids. The inferior and middle turbinates were represented by curved plates that emerge from the lateral walls. The airflow was considered to be incompressible, steady and laminar. Numerical computations show that the main air flux is along the cavity floor, while the turbinate structures direct the flow in an anterior-posterior direction. The presence of the turbinates and the trapezoidal shape of the cavity force more air flux towards the olfactory organs at the top of the cavity.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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