Thermomechanical Characterization of Thermoset Urethane Shape-Memory Polymer Foams

The shape-memory polymer performance of urethane foams compressed under a variety of conditions was characterized. The foams were water-blown thermosets with a closed-cell structure and ranged in density from about 0.25 to 0.75 g/cm(3). Compressive deformations were carried out over a range of strain levels, temperatures, and lateral constraints. Recovery stresses measured between fixed platens were as high as 4 MPa. Recovery strains, measured against loads up to 0.13 MPa, demonstrated the effects of various parameters. The results suggest that compression near the foam glass-transition temperature provided optimal performance. Foams with densities of about 0.5 g/cc and compressed 50% provided a useful balance (time, strain, and load) in the recovery performance. (C) 2009 Wiley Periodicals, Inc.(dagger) J Appl Polym Sci 115: 3217-3229, 2010