Cross-linked polyurethane (PU) is extensively used as thermoset foam; however, methods to directly reprocess PU foam waste derived from commercial sources into similar value materials have not been developed. We demonstrate that introducing dibutyltin dilaurate (DBTDL) into cross-linked PU foams and films enables their reprocessing at elevated temperatures via dynamic carbamate exchange reactions. Both model and commercial cross-linked PU foams were continuously reprocessed using twin-screw extrusion to remove gaseous filler and produce PU filaments or films with elastomeric or rigid thermoset mechanical properties. The properties of microcompounded model PU foam were in excellent agreement with PU film synthesized using the same monomers, indicating that this process occurs efficiently. These findings will enable the bulk reprocessing of commercial thermoset PU waste and inspire the further development of reprocessing methods for other thermosets and the compatibilization of chemically distinct cross-linked materials.
Bibliographical noteFunding Information:
This research was supported by the National Science Foundation (NSF) through the Center for Sustainable Polymers (CHE-1413862). This research made use of the Materials Characterization and Imaging Facility, which receives support from the MRSEC Program (NSF DMR-1121262) of the Materials Research Center at Northwestern University, and the Integrated Molecular Structure Education and Research Center at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental Resource (NSF NNCI-1542205), the State of Illinois, and the International Institute for Nanotechnology. This work made use of the EPIC facility of Northwestern University’s NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. We thank John Beumer for the artistic design of Figure 1.
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