Polymer Nanocomposites Made by Solid-State Shear Pulverization: Achievement of Well-Dispersed Nanofiller Sheets, Nanotubes, and Nanoparticles

A major stumbling block in the field of nanocomposites concerns the achievement of excellent nanofiller dispersion or exfoliation in various polymers using a scalable, industrially applicable process that mixes polymer and nanofiller directly, without need for solvent or polymerization of monomer. Unfortunately, the production of polymer nanocomposites by twin-screw melt extrusion has met with relatively little success, with positive results limited to a subset of polar polymers such as nylon-6. Here we demonstrate that a novel, continuous process called solid-state shear pulverzation (SSSP) can obtain substantially higher levels of dispersion or exfoliation than melt processing for a range of nanofillers, including clay (silicate) sheets, multiwall carbon nanotubes, and alumina nanaparticles. Characterization has been undertaken by electron microscopy, x-ray scattering, differential scanning calorimetry (crystallization kinetics and physical aging behavior), thermogravimetric analysis, dynamic mechanical analysis, rheometry, and impedance spectroscopy.