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  • 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
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  • 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
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    Paper (German National Licenses)
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  • 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
    Location Call Number Expected Availability
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    Paper (German National Licenses)
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