Beijing – While thermoplastic polyurethane can be reprocessed, its properties deteriorate in the light of oxidation and degradation of the polymer chains, and crosslinking poses a recycling problem. Now, a team at the Beijing University of Chemical Technology has come up with a way that balances the ability to recycle the TPU and its mechanical properties.
They found that reprocessable, millable PU could be created if they reacted an enaminone with an isocyanate in a standard Haake mixer, without any solvents being required. The morphology of the network could be tuned via dissociation of the PU’s crosslinked sites.
It was possible to adjust the mechanical properties of the re-crosslinked PU by controlling the addition of the amine and the isocyanate. They found the maximum tensile strength increased by more than 175% after processing the material four times, showing mechanical reinforcement after recycling.
They suggested that this one-step melting method has the potential to create recyclable PU that has both good mechanical performance and properties that can be customised.
The work has been published in the journal Macromolecular Rapid Communications.
