Use of particulate fillers to modify the mechanical properties of resins and rubbers is well documented. The filler modifies not only the mechanical properties of resins but also the physical and chemical properties such as melting temperature and electric resistance and so on. Some fillers, particularly those of very small particle size, reinforce polymers. Strength enhancement depends principally on the particle size of the filler, increasing with decreasing particle size. NANOPIX mini is the ideal instrument for quantifying filler particle size and size distribution in optically opaque samples like rubber where other methods are cumbersome. Shown below is data from rubber samples with different monodisperse filler particle sizes showing clearly distinct scattering patterns.