Porod Scattering Study of Coarsening in Immiscible Polymer Blends

Studies of immiscible blend compatibilization often involve laborious microscopy methods to characterize the changes in the droplet size distribution with time in the melt. Here we explore a simple alternative approach based on Porod scattering from the two phase structure. Although micron-sized droplets in immiscible polymer blends are too large to be fully characterized by small-angle x-ray scattering, Porod scattering measurements of the interfacial area combined with knowledge of the blend volume fraction allows determination of an average droplet diameter from a single scattering measurement. This technique is illustrated in experiments monitoring coarsening of droplet sizes in immiscible PS/PMMA blends prepared either by melt blending or by solid-state shear pulverization.