I try to measure the dielectric constant of composite (polymer + nano powder) and i know the dielectric constant of polymer, how can i know the dielectric constant of powder? is the role of mixture valid here?
Please have a look at my publication. There are several mixture rules available for comparison with your measurements. In an additional publication ( Numericla analysis of complex dielectric mixture formulae, you can find it also among my publications) I have studied several experimental data as well.
Article Comparison of electrical mixture rules for composites