The objective of this research is to develop and assess a cost-effective decrosslinking extrusion process for depolymerizing crosslinked polyurethane (X-PU) composites. The inherent challenges posed by the permanent crosslinked structure of X-PU, along with the presence of fillers and additives, make traditional recycling, recovery, and disposal methods difficult and inefficient. Current technologies (e.g. mechanical regrinding/rebinding, glycolysis, and pyrolysis) often involve high costs, reliance on solvents, extreme heat or pressure, and result in hazardous emissions, all of which limit scalability. This project aims to address these challenges by advancing a solvent-free method that leverages the research team’s prior success in processing neat X-PU to enable practical, large-scale composite depolymerization. 

This project pursues interdisciplinary research on the development, performance evaluation, and initial cost assessment of the new X-PU composite depolymerization technology. Specifically, the project team will perform three research tasks: 

Task1 – Synthesis and characterization of model X-PU/Al composites 

Task2 – Decross-linking extrusion of model X-PU/Al composites and extrudate analysis 

Task3– Initial cost assessment of this new depolymerization strategy 

Special attention will be given to: (1) Studying the thermal stability of the synthesized model X-PU/Al composites to determine decrosslinking extrusion conditions; (2) Determining the depolymerization mechanisms of these model X-PU/Al composites during extrusion and understanding how compositions and processing conditions dictate X-PU’s decrosslinking efficiency and thus decrosslinked extrudates’ structures and properties; and (3) Assessing the costs of the new X-PU composite depolymerization approach developed in this project, as compared to other state-of-the-art technologies. 

This new X-PU composite depolymerization technology will provide the following benefits over other recovery technologies: increased treatment rates, lower operation costs, and reduced waste production. This would enable the Department of War to depolymerize/dispose waste X-PU composites in a high-throughput, and cost-effective manner. (Anticipated Project Completion - 2026)