Analysis of the mechanical behavior of shape memory polymer membranes by nanoindentation, bulging and point membrane deflection tests

The mechanical properties of a thin film of polyurethane shape memory polym er were investigated experimentally. Non-conventional mechanical tests such as nanoindentation, bulging and point membrane deflection are used. The qu antitative results obtained by these three experimental investigations are consistent. These tests, performed at room temperature (approx. 35 K below the glass transition temperature T-g) yield a Young's modulus equal to 2.2 +/- 0.4 GPa for the loading sequence and 3.9 +/- 0.3 GPa for the unloading sequence. A weak residual stress has been determined. Moreover, the viscoel astic behavior of the material has been established. (C) 2000 Elsevier Scie nce B.V. All rights reserved.