The ``Avrami'' equation applies rigorously only to a system which does not change volume on transformation and where the developing regions are spheres. The consequences of the impossibility of achieving these conditions in real systems is discussed. It is shown that excessive approximation combined with the use of weight rather than volume fractions can lead to errors in the exponent n of as much as 0.3. It is emphasized that only at very low conversions can meaningful interpretations be made of the exponent.
REFERENCES
1.
L. Mandelkern in Growth and Perfection of Crystals, edited by R. Doremeus, B. Roberts, and D. Turnbull (John Wiley & Sons, Inc., New York, 1958), p. 467.
2.
3.
W.
Banks
, M.
Gordon
, R. J.
Roe
, and A.
Sharpies
, Polymer
4
, 61
(1963
).4.
5.
6.
7.
See
R. P.
Sheldon
, Polymer Letters
1
, 655
(1963
) for discussion of differences between and calculational methods for various fractions. Confusion in this area is widespread, the present author being somewhat guilty (see Ref. 3 of Sheldon’s paper).
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© 1965 The American Institute of Physics.
1965
The American Institute of Physics
