Residence Time Distribution and Specific Mechanical Energy in Solid-State Shear Pulverization: Processing-Structure-Property Relationships in a Chilled Extruder

Solid-state shear pulverization (SSSP) is a continuous polymer processing methodology based on a modified twin-screw extruder. The unique application of low barrel temperatures and mechanochemistry has contributed to the development of an extensive range of polymer-based materials, from environmentally responsible polymer blends to nanocomposites, for more than 30 years. The complex processing-structure-processing relationships in SSSP can be elucidated by way of integrated, measured covariants that capture the interplay between numerous processing parameters. Residence time distribution and specific mechanical energy are evaluated in a base case polypropylene (PP) study under a full factorial experiment involving screw design, screw speed, and throughput parameters. These factors are in turn correlated to dispersion morphology and thermal property results from a parallel study based on a model PP/carbon black composite. This investigation highlights the tunability of SSSP processing parameters for tailored output with desired purposes and applications. In particular, enhanced residence distribution can be achieved with low screw speed and high throughput settings, leading to high levels of material mixing and shear. POLYM. ENG. SCI., 2019. (c) 2019 Society of Plastics Engineers