A novel approach to predict the recovery time of shape memory polymers

In this paper a novel approach is presented for prediction of the recovery time for a shape memory polymer. The Transient Stress Dip Tests of Fotheringham and Cherry are used to determine the two parameters of a Kelvin-Voigt element. The characteristic retardation time of this element can then be calculated to predict the recovery time. It is shown that this approach is successful in predicting the recovery times for a shape memory polymer drawn and recovered under a range of temperatures. Furthermore it is shown that the ratio of the recovery stress to the draw stress is independent of the drawing conditions to a very good approximation.