Thiocracking of Multi-Materials: High-Strength Composites from Post-Consumer Food Packaging Jars

A significant waste material threatening sustainability efforts are post-consumer food packaging goods. These ubiquitous multi-materials comprise chemically disparate components and are thus challenging targets for recycling. Herein, we undertake a proof-of-principle study in which we use a single-stage method to convert post-consumer multi-material food packaging (post-consumer peanut butter jars) to a high compressive strength composite (PBJS90). This is accomplished by thiocracking the ground jar pulp (10 wt. %) with elemental sulfur (90 wt. %) at 320 °C for 2 h. This is the first application of thiocracking to such mixed-material post-consumer goods. Composite synthesis proceeded with 100% atom economy, a low E factor of 0.02, and negative global warming potential of −0.099 kg CO2e/kg. Furthermore, the compressive strength of PBJS90 (37.7 MPa) is over twice that required for Portland cement building foundations. The simplicity of composite synthesis using a lower temperature/shorter heating time than needed for mineral cements, and exclusive use of waste materials as precursors are ecologically beneficial and represent an important proof-of-principle approach to using thiocracking as a strategy for upcycling multi-materials to useful composites.