Seoul, South Korea – Chemical engineers at the University of Seoul have been exploring a shape memory polyurethane (SMPU) that includes two structurally distinct aliphatic isocyanates, hexamethylene diisocyanate and isophorone diisocyanate. The thermadapt PU also exhibits thermoplasticity.
The hard segment in the SMPU matrix could be tuned by varying the percentage of IPDI in the total isocyanate content. Its shape memory characteristics correlated to the contents of the hard segments, and the crystallinity of the thermadapt SMPU. The best shape memory properties were achieved with 80% IPDI content.
In addition, shape memory properties are closely related to the crystallinity of the PU matrix. The network of the SMPU can be arranged so that its permanent shape is redefined. It is also possible to recover this redefined shape from the temporarily deformed state.
‘Because our thermadapt SMPU system has excellent shape memory characteristics with decent reconfigurability, it can be applied to various practical engineering devices,’ they said.
The work was published in the journal Polymer Testing.