Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    The relaxation of linear flexible polymers which are slightly poly-disperse (1996)
    Springer
    Rheologica acta 35 (1996), S. 645-655 
    Details
    ISSN: 1435-1528
    Keywords: Rheology ; polymers ; poly-dispersity ; linear viscoelasticity ; relaxation time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The relaxation of slightly poly-disperse linear flexible polymers has been expressed in a simplified blending rule which is presumed to be a weighted linear superposition of the relaxation spectra of mono-disperse components which constitute the blend. Discrete components are characterized by their molecular weight M i,weight fraction w i,and relaxation time spectrum H i(λ). ). In contrast to broadly distributed blends in which the small molecules mobilize the large ones and vice versa, we introduce the term “slightly polydisperse” for blends with molecular weight distributions narrow enough to have very little change in the longest relaxation times of each molecular weight component. The properties of this blending rule are analyzed and dynamic data is calculated for slightly poly-disperse polystyrene. As an application, the blending rule is used to determine the characteristic mono-disperse parameters (BSW parameters) of two materials, poly (vinyl methyl ether) and polycarbonate, for which we could not determine their BSW parameters directly since they were not available in nearly monodisperse form. The proposed blending rule can only be applied to systems in which all components are above the entanglement molecular weight, i.e. M i≫M c.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396513
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Mapping of the relaxation patterns of polymer melts with linear flexible molecules of uniform length (1997)
    Springer
    Rheologica acta 36 (1997), S. 330-344 
    Details
    ISSN: 1435-1528
    Keywords: Relaxation time spectrum ; monodisperse polymers ; hypergeometric function ; incomplete gamma function ; linear viscoelasticity ; polymer dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The linear viscoelastic material functions of linear flexible polymers of uniform length are calculated from the BSW spectrum (Baumgaertel et al., 1990, 1992), and explicit analytic expressions are presented for several of the most common material functions for transient and dynamic experiments. However, numerical calculations are presented whenever needed. The BSW spectrum was determined from experimental G″, G″ data of two sets of molten polymers of narrow molecular weight distribution, polystyrene and polybutadiene. The purpose of the mapping is to show a wide range of viscoelastic behavior which otherwise is not available in such comprehensive form. Experimental check of these predictions is still needed in most cases. Also, some insight into the predictions for the non-linear (including the non-equilibrium) viscoelastic behavior is achieved by studying two particular experiments: the start-up of uniaxial extension at constant rate and the start-up of shear flow at constant rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00366674
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Mapping of the relaxation patterns of polymer melts with linear flexible molecules of uniform length (1997)
    Springer
    Rheologica acta 36 (1997), S. 330-344 
    Details
    ISSN: 1435-1528
    Keywords: Key words Relaxation time ; spectrum ; monodisperse polymers ; hypergeometric function ; incomplete gamma function ; linear viscoelasticity ; polymer dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The linear viscoelastic material functions of linear flexible polymers of uniform length are calculated from the BSW spectrum (Baumgaertel et al., 1990, 1992), and explicit analytic expressions are presented for several of the most common material functions for transient and dynamic experiments. However, numerical calculations are presented whenever needed. The BSW spectrum was determined from experimental G′,G″′ data of two sets of molten polymers of narrow molecular weight distribution, polystyrene and polybutadiene. The purpose of the mapping is to show a wide range of viscoelastic behavior which otherwise is not available in such comprehensive form. Experimental check of these predictions is still needed in most cases. Also, some insight into the predictions for the non-linear (including the non-equilibrium) viscoelastic behavior is achieved by studying two particular experiments: the start-up of uniaxial extension at constant rate and the start-up of shear flow at constant rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00366674
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Study of the beam-foil excitation mechanism by use of sulfur and chlorine projectiles (1988)
    Springer
    The European physical journal 10 (1988), S. 457-466 
    Details
    ISSN: 1434-6079
    Keywords: 34.50.Fa ; 34.70.+e
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experimental relative level population data have been analysed for beam-foil excited S VI at 3 MeV and C1 VII at 5.5 MeV. For S VI, the level population is fairly independent of the principal quantum numbern (4≦n≦9), whereas a pronounced maximum is found for levels withn=8 in Cl VII. A two-step model has been applied to calculate theoretical values for the relative level populations. Satisfyingly good agreement is found between experiment and theory. The results confirm the previously proposed idea that at these fairly low projectile velocities, final projectile levels whose binding energies are comparable to or smaller than the binding energies for electrons in the valence band of the foil are mainly populated by transfer of valence band electrons, when the projectile leaves the foil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01425764
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Capture of polarized electrons into excited terms of fast atoms during grazing surface collisions (1992)
    Springer
    The European physical journal 23 (1992), S. 41-53 
    Details
    ISSN: 1434-6079
    Keywords: 34.50.Fa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Fast ions are scattered from magnetized surfaces under grazing angles of incidence. During the interaction with the surface charge exchange is effective and results in a population of stable and excited atomic terms. This capture of electrons is characterized by anisotropic distributions of atomic orbital angular momenta and in addition — for magnetized targets — by anisotropic distributions of electronic spins. We will discuss in some detail, how these anisotropic distributions can be studied via the analysis of the state of polarization of the fluorescent light, emitted in electronic transitions from excited terms of free atoms after the impact with the surface. We show that a defined variation of the magnetization of the target affects the polarization of the emitted light in a characteristic way, which allows to deduce the electronic spin polarization of the atoms. The method implies some perspectives with respect to the study of magnetic properties of the vacuum-solid interface well above the topmost layer of surface atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01436701
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Population of NaI-terms in grazing ion surface collisions (1990)
    Springer
    The European physical journal 17 (1990), S. 109-117 
    Details
    ISSN: 1434-6079
    Keywords: 34.50.Fa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The population of NaI 3p- and 4d-terms after grazing collisions of fast Na+-ions with a clean Al(111)-surface is studied via optical spectrometry. The ratio of level populationsN(3p)/N(4d) is investigated in dependence on projectile velocity under different experimental conditions. For clean targets and a defined geometry of detection a threshold for excitation of the 4d-term is observed. The data are described by a model of population via resonant one electron tunneling which incorporates the effects of the projectile velocity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01437664
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...