Morphology and Toughness Enhancements in Recycled High-Density Polyethylene (rHDPE) via Solid-State Shear Pulverization (SSSP) and Solid-State/Melt Extrusion (SSME)
Solid-state, mechanochemical polymer processing techniques are explored as an effective and sustainable solution to appearance and performance issues commonly associated with recycled plastic products. Post-consumer high-density polyethylene (HDPE) from milk jugs is processed via conventional twin screw extrusion (TSE), solid-state shear pulverization (SSSP), and solid-state/melt extrusion (SSME), and compared to the as-received and virgin forms regarding output attributes and mechanical properties, as well as morphology. Solid-state processing methods, particularly SSME with a harsh screw configuration, produce samples with consistent appearance and melt flow characteristics. Tensile ductility/toughness and impact toughness are enhanced by up to 11-fold as compared to the as-received sample, to a level near and above those of an equivalent virgin HDPE. Calorimetry, optical microscopy, X-ray scattering, and rheology characterization reveal that the mechanical improvements result from a favorable combination of physical and molecular changes in rHDPE, such as impurity size reduction, spherulite size enlargement, and chain branching. (C) 2015 Wiley Periodicals, Inc.
Journal of Applied Polymer Science
Miu, Evan V.; Fox, Andrew J.; Jubb, Samuel H.; and Wakabayashi, Katsuyuki. "Morphology and Toughness Enhancements in Recycled High-Density Polyethylene (rHDPE) via Solid-State Shear Pulverization (SSSP) and Solid-State/Melt Extrusion (SSME)." Journal of Applied Polymer Science (2016) : 43070.