Cluster size distribution of spherical nanoparticles in polymer nanocomposites: rheological quantification and evidence of phase separation

Currently, it is a great challenge to characterize the dispersion quality of nanoparticles in nanocomposites through experimental techniques. In this work, we suggest a new rheological method based on the strain rate amplification effect to determine the cluster size distribution in polymer nanocomposites. The dispersion exponents of nanoparticles from this rheological method are in good agreement with the cluster analysis of transmission electron microscope (TEM) images. We also obtain a critical value of the dispersion exponent from the effective specific surface area of clusters, which separates the well-dispersed state and the phase-separated state. Our results indicate that rheology can be used as a convenient and effective structural analysis method to characterize the nanoparticle cluster size distribution in polymer nanocomposites.