Rheologica Acta

, Volume 7, Issue 4, pp 379–392 | Cite as

Constitutive equations from molecular network theories for polymer solutions

  • A. S. Lodge


In this mainly expository paper, constitutive equations based on the network models ofYamamoto,Lodge, andKaye are re-derived in a common notation involving the use of base vectors embedded in the deforming macroscopic continuum. The derivations are thereby simplified in some respects and the differences of detail between the models are clarified. InLodges theory, the sub-network superposition assumption is replaced by alternative assumptions concerning the creation and loss of network segments, and the theory is extended to non-Gaussian networks.Kayes theory is extended to allow for the presence of entanglement junctions of different complexities.



= 3/(2n l2)


= number of freely-jointed links, each of lengthl, in a strand


= time-average (or ensemble-average) end-to-end vector for a typical network segment;r = magnitude ofr


=Helmholtz free energy per unit volume of solution


=Boltzmanns constant


= absolute temperature

F(x, n, t) d3x=F(x1,x2,x3,n, t) dx1dx2dx3

= concentration at timet ofn-segments whoser-vectors lie in the range (x i u i , (x i +dx i )u i )


= orthonormal base vectors, fixed in space;r =x i u i


= linearly independent, time-dependent base vectors, embedded in the macroscopic continuum


= convected components ofr: r =ξ i e i


=e i · e j (scalar product)


= concentration ofn-segments


= det [γ ij ]


= element of matrix reciprocal to matrix


= concentration of segments


= stress components referred to basise1,e2,e3


=π ij +p γ ij ,p arbitrary


= a parameter (of values 1, 2,...) labeling segments according to the complexity of their junctions with the network


= constant probability per unit time that an (n, x)-segment will leave the network

Ψ(ξ, n, x, t' ¦t) d3ξ dt'

= concentration at timett' of (ξ, n, x)-segments which were created in the interval (t', t' + dt')


= rate of creation, per unit volume, of (n, x)-segments

N* (t− t') dt'

= concentration at timet≥t' of segments which were created in the interval (t', t'+dt')


= density of configurations available to a strand having one end fixed at a given point and the other end within a volume elementdV about a second given point


= primary and secondary differences of normal cartesian stress components for a liquid in steady shear flow in which the velocity components arev1=Gx2,v2=v3=0


= shear rate

Φ (r, n, T)

= contribution toA from a typical (r, n)-segment at timet

β (r, n)

= probability per unit time that a given (r, n)-segment will leave the network

G(r, n, t) d3x dt

= concentration of (r, n)-segments created during (t, t + dt)

Ψ (ξ, n, t′¦t) d3ξ dt′

= concentration at timet≥t′ of (ξ, n)-segments which were created during (t′, t′ + dt′)


=r(t′) r″ =r(t″)


= components of extra stress tensor referred to basisu1,u2,u3

c (t)

= a cartesian space tensor defined byr(t) =e(*) · r(0)


=r(0) in [7.22],r(t′) in [7.24]


= transpose ofe


= reciprocal of e


=g[Q i (t), Q2(t)]= stress-dependent probability per unit time at timet of the loss of any given network junction

Q1(t), Q2(t)

= functions of invariants of stress at timet, defined by [8.11], [8.12]

g″xn ≡ g [Qi(t″), Q2(t″), x,n]

= probability per unit time at timet″ of the loss of any given (n, x)-segment


= concentration of (n, x)-segmentsN0 = concentration of junctions


=N*0/N0, a number whose value is about 1 or 2


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  1. 1).
    Treloar, L. R. G. “The Physics of Rubber Elasticity”, 2nd Edition). (Oxford 1958).Google Scholar
  2. 2).
    James, H. M. J. Chem. Phys.15, 651 (1947).CrossRefGoogle Scholar
  3. 3).
    Green, M. S. andA. V. Tobolsky, ibid.14, 80 (1946).CrossRefGoogle Scholar
  4. 4).
    Lodge, A. S., Trans. Faraday Soc.52, 120 (1956).CrossRefGoogle Scholar
  5. 5).
    Lodge, A. S., Kolloid-Z.171, 46 (1960).CrossRefGoogle Scholar
  6. 6).
    Yamamoto, M., J. Phys. Soc. Japan11, 413 (1956).Google Scholar
  7. 7).
    Yamamoto, M., ibid.12, 1148 (1957).Google Scholar
  8. 8).
    Yamamoto, M., ibid.13, 1200 (1958).Google Scholar
  9. 9).
    Kaye, A., Brit. J. Appl. Phys.17, 803 (1966).Google Scholar
  10. 10).
    Lodge, A. S., In Proc. 2nd Int. Congr. Rheol.: “Rheology” London 1954, 229.Google Scholar
  11. 11).
    Lodge, A. S., “Elastic Liquids” London-New York (1964).Google Scholar
  12. 12).
    Oldroyd, J. G., Proc. Roy. Soc.A 200, 523 (1950).Google Scholar
  13. 13).
    Scanlon, J., In “Rheology of Elastomers”. Ed.Mason andWookey, 58, (London 1958).Google Scholar
  14. 14).
    Flory, P. J., Trans. Faraday Soc.56, 722 (1960).CrossRefGoogle Scholar
  15. 15).
    Wall, F. T., J. Chem. Phys.10, 485, eq. (1) (1942).CrossRefGoogle Scholar
  16. 16).
    Wang, M. C. andE. Guth, J. Chem. Phys.20, 1144 (1952).CrossRefGoogle Scholar
  17. 17).
    Adams, N. andA. S. Lodge, Phil. Trans.A 256, 149 (1964).Google Scholar
  18. 18).
    Huppler, J., Trans. Soc. Rheol.9: 2, 273 (1965).CrossRefGoogle Scholar
  19. 19).
    Graessley, W. W., J. Chem. Phys.43, 2696 (1965).CrossRefGoogle Scholar
  20. 20).
    Macdonald, I. F. andR. B. Bird, J. Phys. Chem.70, 2068 (1966).Google Scholar
  21. 21).
    Broadbent, J. M., A. Kaye, A. S. Lodge, andD. G. Vale, Nature, London217, 55 (1968).Google Scholar

Copyright information

© Dr. Dietrich Steinkopff Verlag 1968

Authors and Affiliations

  • A. S. Lodge
    • 1
  1. 1.Mathematics Research Center, United States ArmyUniversity of WisconsinMadisonUSA

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