Effective electrical resistivities and static relative permittivities of
binary powder mixtures were measured and compared to theoretical
equations given by Generalized Mixture Rule (GMR). The measured values
for mixtures were influenced by the resistivity and permittivity of the
pure component materials, the particle sizes and by the sticking between
the different particles. According to the Random Model (RM), the
effective resistivity and relative permittivity of any randomly packed
mixture material can be calculated from the component resistivities and
relative permittivities, respectively, and their concentrations. It was
shown that RM gave good predictions for both quantities for powders if
the particle sizes of the component materials were almost the same.
However, this was not the case when large NaCl particles were mixed with
fine sugar particles. When these mixtures were prepared, finer, more
numerous sugar particles coated the larger NaCl particles, and the
mixtures were not random but closer to the series configuration. Effect
of particle size was studied briefly by mixing very fine NaCl particles
with sugar of similar size. With these mixtures, results predicted by RM
were obtained.