FRACTAL AGGREGATES OF POLYDISPERSE PARTICLES

In this work we examine structural effects of particle polydispersity on fractal aggregates by performing DLCA simulations with multiple pri mary particle sizes. We show that the fractal structure and the form o f the cutoff function that describes the gross shape of the aggregates is unaffected by the details of the primary particle size distributio n. The scattering behavior is evaluated in terms of partial structure factors, and depending on the details of primary particle size distrib ution and contrast, the scattering curve can deviate significantly fro m the typical q(-Df) behavior at the high q end of the spectrum. We al so develop an expression for average primary particle size that allows the calculation of aggregate solid volume fraction for fractal aggreg ates with polydisperse primary particles. (C) 1998 Academic Press