Appraisal of the Cox-Merz rule for well-characterized entangled linear and branched polymers

详细信息    查看全文

• 作者：Frank Snijkers (1)
  Dimitris Vlassopoulos (1) (2)
  
• 关键词：Cox ; Merz rule ; Shear viscosity ; Linear polymer melts ; Branched polymer
• 刊名：Rheologica Acta
• 出版年：2014
• 出版时间：December 2014
• 年：2014
• 卷：53
• 期：12
• 页码：935-946
• 全文大小：879 KB
• 参考文献：1. Al-Hadithi TSR, Barnes HA, Walters K (1992) The relationship between the linear (oscillatory) and nonlinear (steady-state) flow properties of a series of polymer and colloidal systems. Colloid Polym Sci 270:40 CrossRef
  2. Andreev M, Feng H, Yang L, Schieber JD (2014) Universality and speedup in equilibrium and nonlinear rheology predictions of the fixed slip-link model. J Rheol 58:723-36 CrossRef
  3. Archer LA, Juliani A (2004) Linear and nonlinear viscoelasticity of entangled multiarm (Pom-Pom) polymer liquids. Macromolecules 37:1076-088 CrossRef
  4. Auhl D, Ramirez J, Likhtman AE, Chambon P, Fernyhough C (2008) Linear and nonlinear shear flow behavior of monodisperse polyisoprene melts with a large range of molecular weights. J Rheol 52:801-35 CrossRef
  5. Barnes HA, Hutton JF, Walters K (1989) An introduction to rheology. Elsevier
  6. Booij HC, Leblans P, Palmen J, Tiemersma-Thoone G (1983) Nonlinear viscoelasticity and the Cox-Merz relations for polymeric fluids. J Polym Sci, Polym Phys Ed 21:1703-711 CrossRef
  7. Chang T (2005) Polymer characterization by interaction chromatography. J Polym Sci B Polym Phys 43:1591-607 CrossRef
  8. Cox WP, Merz EH (1958) Correlation of dynamic and steady flow viscosities. J Polym Sci 28:619 CrossRef
  9. Das C, Inkson NJ, Read DJ, Kelmanson MA, McLeish TCB (2006) Computational linear rheology of general branch-on-branch polymers. J Rheol 50:207-34 CrossRef
  10. Das C, Read DJ, Auhl D, Kapnistos M, den Doelder J, Vittorias I, McLeish TCB (2014) Numerical prediction of nonlinear rheology of branched polymer melts. J Rheol 58:737-58 CrossRef
  11. de Gennes PG (1971) Reptation of a polymer chain in the presence of fixed obstacles. J Chem Phys 55:572-79 CrossRef
  12. Dealy JM, Larson RG (2006) Structure and rheology of molten polymers. Publishers, Hanser CrossRef
  13. Doi M (1983) Explanation for the 3.4-power law for viscosity of polymeric liquids on the basis of the tube model. J Polym Sci, Polym Phys Ed 21:667-84 CrossRef
  14. Doi M, Edwards SF (1978a) Dynamics of concentrated polymer systems. Part 1—brownian motion in the equilibrium state. J Chem Soc, Faraday Trans 2(74):1789-801 CrossRef
  15. Doi M, Edwards SF (1978b) Dynamics of concentrated polymer systems. Part 2—molecular motion under flow 1802-1817. J Chem Soc, Faraday Trans 2:74
  16. Doi M, Edwards SF (1978c) Dynamics of concentrated polymer systems. Part 3—the constitutive equation. J Chem Soc, Faraday Trans 2(74):1818-832 CrossRef
  17. Doi M, Edwards SF (1979) Dynamics of concentrated polymer systems. Part 4—rheological properties. J Chem Soc, Faraday Trans 2(75):38-4 CrossRef
  18. Doi M, Edwards SF (1986) The theory of polymer dynamics. Clarendon Press
  19. Doi M, Takimoto J (2003) Molecular modelling of entanglement. Phil Trans R Soc Lond A 361:641-52 CrossRef
  20. Ferri D, Lomellini P (1999) Melt rheology of randomly branched polystyrenes. J Rheol 43:1355-372 CrossRef <
• 作者单位：Frank Snijkers (1)
  Dimitris Vlassopoulos (1) (2)
  
  1. Foundation for Research and Technology—Hellas (FORTH), Institute of Electronic Structure and Laser (IESL), Heraklion, 71110, Crete, Greece
  2. Department of Materials Science and Technology, University of Crete, Heraklion, 71003, Crete, Greece
  
• ISSN：1435-1528

文摘

We present a critical assessment of the range of validity of the empirical Cox-Merz rule for a wide range of model entangled polymer samples with a well-defined molecular structure, from linear monodisperse and polydisperse polymers, to branched model polymers (i.e. stars, H-polymers, and combs) and blends of linear polymers of the same chemistry. We focus on melts and concentrated solutions. Overall, we find that the simple empirical rule is obeyed rather well for the investigated cases. As often reported in the literature, relatively small systematic failures occur with the steady viscosity being below the complex one at high rates for most polymers, with linear polydisperse polymers (with a polydispersity index of about 2) being a notable exception. For the latter polymers, the rule is obeyed identically within experimental error. More unusual failures, with the steady shear viscosity being higher than the complex viscosity, are found for branched polymers with more than one branch point. More specifically, these unusual failures are observed at very high branching levels, when the backbone of the polymer is being stretched at low rates due to the motion of the branch points. The extra stress coming for the stretch renders the steady viscosity higher than the complex one. Due to the well-characterized nature of the combs, we can state that failures of the latter type are only apparent when the branches comprise more than 70?% of the molecular structure of the comb. This estimation could serve as a rough guideline in applications, although it is only a necessary and not sufficient condition for these failures to occur.