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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of population economics 3 (1990), S. 53-71 
    ISSN: 1432-1475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Sociology , Economics
    Notes: Abstract The paper investigates into the determinants of the personal distribution of income and wealth. In an overlapping generations model all individuals are assumed to be identical except for their inherited wealth. Since life time is random the bequest of an individual and thus the inherited stock of capital of its children are stochastic variables. Taxation and social security contributions affect life cycle savings, bequests, and, eventually, the distribution of income and wealth in the society. It is shown that, in general, higher tax rates reduce distributive inequality as long as the rate of interest is exogenously given. In steady state, however, where the rate of interest is determined endogenously, increasing taxation and higher social security payments both diminish the capital labor ratio so that the rate of interest rises. If this interest effect is strong enough then it may outbalance the tendency toward more equality because higher interest rates enhance initial differences in the distribution of both income and wealth and, eventually, the inequality in the distribution of income and wealth in the society.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 271 (1993), S. 824-833 
    ISSN: 1435-1536
    Keywords: Polypropylene ; EPDM ; interphase
    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 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.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 268 (1990), S. 528-535 
    ISSN: 1435-1536
    Keywords: Polypropylene/polystyreneblends ; nucleation ; isothermalcrystallization ; spheruliticgrowth
    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 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.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 269 (1991), S. 1212-1223 
    ISSN: 1435-1536
    Keywords: Self-reinforced polymer composites ; mechanical properties ; interface ; transfer of load
    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 The tensile properties of self-reinforced polypropylene composites, obtained by rapid extension of an isotactic polypropylene/atactic polypropylene melt, have been measured and correlated to morphological parameters derived from x-ray experiments. The longitudinal morphology of the core-fibrils is found to be independent of sample composition, while the lateral thickness of the fibers varies between 220 Å for iPP and 110 Å for the blend containing 50 wt.% aPP. Critical fiber lengths, as a function of sample composition and the elastic modulus and the yield stress of the fibers, could be determined. While the number of corefibrils increases with mass fraction of atactic polypropylene, the length of the lateral interface between fiber and matrix and the interface volume decreases with increasing aPP mass fraction. It is shown that this interface is responsible for the mechanical behavior of the composite by effecting the transfer of load from matrix to fiber.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 26 (1991), S. 3253-3256 
    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 The crystalline order in blends of thermoplastics such as polyethylene (PE) and isotactic polypropylene (iPP) with trans octenylene rubber (TOR) has been investigated by small-angle X-ray scattering. Interface distribution functions have been used to evaluate the SAXS. It was found, that the crystal morphology depends strongly on sample composition. At 10% TOR content both thermoplastics change their supermolecular structure in a characteristic way: while in the PE/TOR blends the crystal morphology of polyethylene becomes bimodal, the lamellar order is increased in the iPP/TOR blends. This behaviour is a consequence of finer dispersion of TOR in the matrix which causes the interface area to increase.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 29 (1994), S. 4708-4712 
    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 The secondary crystallization of isotactic polypropylene in its blend with the elastomers ethylene-propylene-diene-terpolymer (EPDM) and trans-polyoctenylene (TOR), which occurs during isothermal crystallization, has been measured by time-dependent recording of X-ray wide-angle scattering. From the results, Avrami exponents were determined, which show that secondary crystallization takes place primarily within the already formed spherulites. Avrami exponents of the primary crystallization have been determined by the same method and also by observation of the spherulitic growth in the polarization microscope. It was found that both elastomers have different effects on the crystallization behaviour of the polypropylene.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 25 (1990), S. 4704-4707 
    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 The crystal morphology of the weld lines in injection moulded polypropylene parts has been investigated by X-ray scattering and transmission electron microscopy. Wide angle X-ray scattering curves reveal two crystal modifications in the samples: the monoclinic α-modification and the hexagonal β-modification. The fraction of the crystallinity which is due to the β-modification is lower in the vicinity of the weld line and increases with the distance from the weld line. Transmission electron micrographs reveal that in the weld line no crystallization of β-spherulites occurs.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 27 (1992), S. 1171-1174 
    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 The crystallization behaviour of isotactic polypropylene (iPP) blended withtrans-octenylene rubber (TOR) has been investigated by optical microscopy. It is found that crystallization kinetical parameters like nucleation densities, Avrami exponents and spherulitic growth rates are strongly dependent on the TOR concentration in the blend. While at 10% TOR content the nucleation density passes through a maximum, both the Avrami exponent and the spherulitic growth rate are minimal. Due to an increased dispersion of TOR in iPP at 10% TOR concentration and the subsequent formation of interfaces, the nucleation changes from preferentially homogeneous to preferentially heterogeneous. The concentration oftrans double bonds in the TOR chain has no influence on the crystallization behaviour of the samples.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 28 (1993), S. 1685-1688 
    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 The morphology of isotactic polypropylene (iPP)/linear low-density polyethylene (LLDPE) blends, compatibilized with ethylene-propylene block copolymer (EP) and two types of styrene-ethylene/butylene-styrene triblock copolymer (SEBS), one containing maleic anhydride, the other no reactive sites, has been investigated by using small-angle X-ray scattering by evaluating their interface distribution functions. To characterize the crystallization behaviour of the blends, their spherulitic growth rates have been measured under the polarizing microscope and nucleation and crystallization kinetics data have been evaluated. The addition of LLDPE to iPP alone has a pronounced effect on the lamellar morphology of the iPP. Adding compatibilizer to the iPP/LLDPE blend leads to a further decrease of the lamellar thickness. Concurrently the nucleation density increases while the Avrami exponent drops from n∼2.3 for iPP to n=0.74 for the iPP/LLDPE/SEBS blend. It is concluded that the compatibilizer causes the polyethylene component to become more highly dispersed in the polypropylene matrix.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 31 (1993), S. 585-592 
    ISSN: 1741-0444
    Keywords: Air Flow ; Human ; Nasal cavity ; Nose ; Turbinate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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