We have shown that simple power-law dynamics is expected for flexible
fractal objects. Although the predicted behavior is well established for
linear polymers, the situationm is considerably more complex for
colloidal aggregates. In the latter case, the observed K-dependence of
(r) can be explained either in terms of non-asymptotic hydrodynamics or
in terms of weak power-law polydispersity. In the case of powders
(alumina, in particular) apparent fractal behavior seen in static
scattering is not found in the dynamics. ID. W. Schaefer, J. E. Martin,
P. Wiitzius, and D. S. Cannell, Phys. Rev. Lett. 52,2371 (1984). 2 J. E.
Martin and D. W. Schaefer, Phys. Rev. Lett. 5:1,2457 (1984). 3 D. W.
Schaefer and C. C. Han in Dynamic Light Scattering, R. Pecora ed,
Plenum, NY, 1985) p. 181. 4 P. Sen, this book. S J. E. Martin and B. J.
Ackerson, Phys. Rev. A:11, 1180 (1985). 6 J. E. Martin, to be published.
7 D. A. Weitz, J. S. Huang, M. Y. Lin and J. Sung, Phys. Rev. Lett.
53,1657 (1984) . 8 J. E. Martin, D. W. Schaefer and A. J. Hurd, to be
published; D. W. Schaefer, K. D. Keefer, J. E. Martin, and A. J. Hurd,
in Physics of Finely Divided Matter, M. Daoud, Ed., Springer Verlag, NY,
1985. 9 D. W. Schaefer and A. J. Hurd, to be published. lOJ. E. Martin,
J. Appl. Cryst. (to be published).