Improving Sustainability: Processing Difficult-to-Recycle Plastics Via Solid-State Shear Pulverization of Post-Industrial Ultrahigh Molecular Weight Polyethylene

Ultra-high molecular weight polyethylene (UHMWPE) is one of the prominent high performance thermoplastics in biomedical, leisure, and coating applications. Large-scale recycling of UHMWPE is extremely difficult due to the high melt viscosity of the material as well as its exceptional chemical resistance and impact strength. There is a need for a mechanical recycling method that can effectively sustain the outstanding physical properties of the material. Solid-state shear pulverization (SSSP) is a continuous, twin screw extruder-based processing technique in which low-temperature application of shear and compressive forces impart changes in structure at different length scales to overcome the challenges of difficult-to-recycle polymers. This paper investigates the use of SSSP in mechanically recycling post-industrial scrap UHMWPE (rUHMWPE) material from a partnering local manufacturer. The SSSP-processed particles are flat, micron-scale flakes with enhanced surface area, which can sinter easily when compression molded. The processed rUHMWPE samples also exhibit enhanced ductility and toughness compared to the as-received scrap material, based on the tunable mechanochemical modification by the SSSP process.