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The European Physical Journal E

, Volume 17, Issue 1, pp 69–76 | Cite as

Effects of the rate of evaporation and film thickness on nonuniform drying of film-forming concentrated colloidal suspensions

  • T. Narita
  • P. Hébraud
  • F. Lequeux
Original Article

Abstract.

In this paper, we report on nonuniform distribution of film-forming waterborne colloidal suspensions above the critical concentration φc of the colloidal glass transition during drying. We found that colloidal suspension films dry nonuniformly when the initial rate of evaporation E and/or the initial thickness l0 are high. We found that a Peclet number Pe, defined as Pe = El0/D, where D is the diffusion coefficient of the colloids in the diluted suspensions, does not predict uniformity of drying of the concentrated suspensions, contrary to the reported work on drying of diluted suspensions. Since the colloidal particles are crowded and their diffusive motion is restricted in concentrated suspensions, we assumed that above φc water is transported to the drying surface by hydrodynamic flow along the osmotic pressure gradient. The permeability of water through channels between deforming particles is estimated by adapting the theory of foam drainage. We defined a new Peclet number Pe’ by substituting the transport coefficient of flow (defined as the permeability divided by the viscosity, multiplied by the osmotic pressure gradient) for the diffusion coefficient. This extended Peclet number predicted the nonuniform drying with a criterion of Pe’ > 1. These results indicate that the mechanism of water transport to the drying surface in concentrated suspensions is water permeation by osmotic pressure, which is faster than mutual diffusion between water and particles --that has been observed in diluted suspensions and discussed by Routh and Russel. The theory fits well the experimental drying curves for various thicknesses and rates of evaporation. The particle distribution in the drying films is also estimated and it is indicated that the latex distribution is nonuniform when Pe’ > 1.

PACS.

47.55.Mh Flows through porous media 82.70.Kj Emulsions and suspensions 

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References

  1. 1.
    J.L. Keddie, Mater. Sci. Eng. Rep. 21, 101 (1997).Google Scholar
  2. 2.
    J.L. Keddie, P. Meredith, R.A.L. Jones, A.M. Donald, Macromolecules 28, 2673 (1995).Google Scholar
  3. 3.
    R.D. Deegan, Olgica Bakajin, T.F. Dupont, G. Huber, S.R. Nagel, T.A. Witten, Nature 389, 827 (1997). Google Scholar
  4. 4.
    J.M. Salamanca, E. Ciampi, D.A. Faux, P.M. Glover, P.J. McDonald, A.F. Routh, A.C.I.A. Peters, R. Satguru, J.L. Keddie, Langmuir 17, 3202 (2001).Google Scholar
  5. 5.
    F. Parisse, C. Allain, J. Phys. II 6, 1111 (1996).Google Scholar
  6. 6.
    A.F. Routh, W.B. Russel, Langmuir 15, 7762 (1999).Google Scholar
  7. 7.
    A.F. Routh, W.B. Zimmerman, Chem. Eng. Sci. 59, 2961 (2004).Google Scholar
  8. 8.
    L.A. Brown, C.F. Zukoski, L.R. White, AIChE J. 48, 492 (2002).Google Scholar
  9. 9.
    A.F. Routh, W.B. Russel, Ind. Eng. Chem. Res. 40, 4302 (2001).Google Scholar
  10. 10.
    J.-P. Gorce, D. Bovey, P.J. McDonald, P. Palasz, D. Taylor, J.L. Keddie, Eur. Phys. J. E 8, 421 (2002).PubMedGoogle Scholar
  11. 11.
    P.N. Pusey, W. van Megen, Phys. Rev. Lett. 59, 2083 (1987).PubMedGoogle Scholar
  12. 12.
    T.G. Mason, D.A. Weitz, Phys. Rev. Lett. 75, 2770 (1995).PubMedGoogle Scholar
  13. 13.
    L.A. Brown, C.F. Zukoski, L.R. White, AIChE J. 49, 362 (2003).Google Scholar
  14. 14.
    T. Narita, C. Beauvais, P. Hébraud, F. Lequeux, Eur. Phys. J. E 14, 287 (2004).PubMedGoogle Scholar
  15. 15.
    S.A. Koehler, S. Hilgenfeldt, H.A. Stone, Phys. Rev. Lett. 82, 4232 (1999).Google Scholar
  16. 16.
    S.A. Koehler, S. Hilgenfeldt, H.A. Stone, Langmuir 16, 6327 (2000).Google Scholar
  17. 17.
    V. Carrier, S. Destouesse, A. Colin, Phys. Rev. E 65, 061404 (2002).Google Scholar
  18. 18.
    D. Desai, R. Kumar, Chem. Eng. Sci. 49, 1361 (1982).Google Scholar
  19. 19.
    R.A. Leonard, R. Lemlich, AIChE J. 11, 18 (1965).Google Scholar
  20. 20.
    R. Phelan, D. Weaire, E.A.J.F. Peters, G. Verbist, J. Phys. Condens. Matter 8, L475 (1996).Google Scholar
  21. 21.
    C. Bonnet-Gonnet, L. Belloni, B. Cabane, Langmuir 10, 4012 (1994).Google Scholar
  22. 22.
    S.G. Croll, J. Coat. Technol. 58, 41 (1986).Google Scholar

Copyright information

© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2005

Authors and Affiliations

  1. 1.CNRS-UMR7615 Physico-Chimie des Polymères et des Milieux DispersésESPCIParis cedex 05France

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