Fractal aggregates of polydisperse particles

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