Rheology of Polydisperse Star Polymer Melts: Extension of the Parameter-Free Tube Model of Milner and McLeish to Arbitrary Arm-Length Polydispersity

Slot, Johan J.M. and Steeman, Paul A.M. (2005) Rheology of Polydisperse Star Polymer Melts: Extension of the Parameter-Free Tube Model of Milner and McLeish to Arbitrary Arm-Length Polydispersity. Macromolecular Theory and Simulations, 14 (6). pp. 387-399. ISSN 1022-1344

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Abstract:	This paper considers the extension of the parameter-free tube model of Milner and McLeish for stress relaxation in melts of monodisperse star polymers to star polymers whose arms have a continuous molecular weight distribution such as the Flory distribution in the case of star-nylons and star-polyesters. Exact expressions are derived for the relaxation spectrum and the relaxation modulus for star polymers having an arbitrary continuous arm-length distribution. For a Flory distribution a comparison is made with results of dynamic measurements on a melt of 8-arm poly(-caprolactone) (PCL) stars. An excellent quantitative agreement over a large frequency range is found, however, only if one treats, in contrast with the original parameter-free tube model approach, the entanglement molecular weight that determines the relaxation spectrum as a fitting parameter independent of the entanglement molecular weight of the linear PCL. This discrepancy is not in anyway related to the polydispersity in arm-length, but a consequence of the thermorheological complexity of the PCL stars. A similar discrepancy has been observed for hydrogenated polybutadiene stars, as described by Levine and Milner.
Item Type:	Article
Copyright:	© 2005 Wiley InterScience
Research Group:	Computational Biophysics (CBP)
Link to this item:	http://purl.utwente.nl/publications/72013
Official URL:	http://dx.doi.org/10.1002/mats.200500008
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