Amorphous Polymer Network Shape Memory Prediction
Amorphous Polymer Network Shape Memory Prediction
Thursday, May 23, 2013: 11:15
Congress Hall 2 (OREA Pryamida Hotel)
This work aims at proving that the shape memory property of amorphous polymer networks is a mere expression of the intrinsic time-temperature equivalence and viscoelasticity properties of the materials. For this purpose, an acrylate network was synthesized in the laboratory. The time-temperature superposition property and the material viscoelasticity are determined by dynamic mechanical analysis (DMA). The material shows to satisfy to the Williams-Landel-Ferry time temperature equivalence law and its viscoelasticity is well represented by a generalized Maxwell model.
Shape memory thermomechanical tests are performed in uniaxial tension according to the following procedure: 1) the material is heated at a high temperature, 2) it is uniaxially deformed up to 50%, 3) the material is cooled down while maintaining the applied deformation, 4) the stress is released at low temperature, and finally 5) the shape recovery is activated by heating the sample at a constant controlled heating rate. During these tests, we studied the effect on the shape memory of the temperature of temporary shape setting, of the heating ramp and of the amount of deformation applied at high temperature.
Finally, the complete thermomechanical shape memory tests are simulated using the time-temperature equivalence property and the viscoelastic property determined by DMA tests for the mechanical behavior of the polymer. A good agreement between the simulations and the experimental results is obtained for each test condition.
Shape memory thermomechanical tests are performed in uniaxial tension according to the following procedure: 1) the material is heated at a high temperature, 2) it is uniaxially deformed up to 50%, 3) the material is cooled down while maintaining the applied deformation, 4) the stress is released at low temperature, and finally 5) the shape recovery is activated by heating the sample at a constant controlled heating rate. During these tests, we studied the effect on the shape memory of the temperature of temporary shape setting, of the heating ramp and of the amount of deformation applied at high temperature.
Finally, the complete thermomechanical shape memory tests are simulated using the time-temperature equivalence property and the viscoelastic property determined by DMA tests for the mechanical behavior of the polymer. A good agreement between the simulations and the experimental results is obtained for each test condition.