In the current study, the kinetics and thermodynamics of the melt-processed nanoclay-filled polypropylene (PP)/low density polyethylene (LDPE) blend ternary composites are investigated and how they control the nano/micro-structure development and properties. The morphological characteristics suggest that the nano/micro-structure of the PP/LDPE (80/20) blend can be controlled by addition of pristine nanoclay or by adding a combination of nanoclay and maleated compatibilizers. Simultaneous mixing of blended polymers, maleated compatibilizers, and nanoclay results in homogeneous distribution of intercalated silicate layers in all the phases of the blend, a characteristic which significantly affects the thermal stability and rheological properties of the blend composites. Regardless of the phase in which the nanoclay is localized, the morphology, and hence the properties, of the neat blend are inferior to those of the ternary composites.