Most of us have played with lumps of “silly putty,” the strange substance shown in the photographs on page 34. Given a bit of time, this material flows like a viscous liquid. Forced to respond quickly, it bounces like rubber. We can trace this “viscoelastic” behavior, which shows up in all polymer melts, to the knotting of the chains of “monomers” that make up the polymers. Shearing forces tend to undo certain knots, but this takes a finite time τ. In a time greater than τ the original knots fade out, and the melt flows. Over shorter times the original knots are all present, and the melt behaves like an elastic network.
REFERENCES
1.
J. D. Ferry, Viscoelastic properties of polymers, Wiley, New York (1970);
J. Walker, Sci. Am., November 1978, page 186.
2.
For a physical approach to the classification of knots, see
R.
Ball
, M.
Mehta
, Journ. Phys. (Paris)
42
, 1193
(1981
).3.
4.
5.
6.
7.
P. Flory, Principles of Polymer Chemistry, Cornell U.P., Ithaca (1953).
P. G. de Gennes, Scaling Concepts in Polymer Physics, Cornell U.P., Ithaca (1979).
8.
9.
10.
P.
Callaghan
, D.
Pinder
, 14
, 1334
(1981
).11.
12.
F. Brochard, P. G. de Gennes, Physiochemical Hydrodynamics, to be published.
13.
See, for instance,
I.
Mita
, K.
Horie
, M.
Takeda
, Macromolecules
14
, 1428
(1981
);14.
P.
Gilmore
, R.
Farabella
, R.
Laurence
, Macromolecules
13
, 880
(1980
);15.
K.
Jud
, H.
Kausch
, J. G.
Williams
, J. Materials Sci.
16
, 204
(1981
).16.
P. G. de Gennes in Microscopic Aspects of Adhesion and Lubrication, J. M. Georges, ed., Elsevier, Amsterdam (1982), page 355;
Detailed calculations on the interdigitation profile are given by
M.
Tirrel
, S.
Prager
, J. Chem. Phys.
10
, 5194
(1981
).17.
18.
submitted to Biopolymers.
19.
20.
S. Alexander, J. Bernasconi, W. Schneider, R. Orbach, in Physics in One Dimension, Springer‐Verlag, New York, solid state series 23 (1981), page 277.
21.
F. Brochard, J. Jouffroy, P. Levinson, Macromolecules, to be published.
This content is only available via PDF.
© 1983 American Institute of Physics.
1983
American Institute of Physics
You do not currently have access to this content.
