Influence of Holding Time on Shape Recovery in a Polyurethane Shape-Memory Polymer

Thursday, May 23, 2013
OREA Pryamida Hotel
Mr. David Manuel Santiago , Universitat Rovira i Virgili, Tarragona, Spain
Dr. Francesc Ferrando , Universitat Rovira i Virgili, Tarragona, Spain
Dr. Silvia De la Flor , Universitat Rovira i Virgili, Tarragona, Spain
Shape Memory Polymers (SMP) are materials that are capable of change their shape when an external stimulus is applied to them [1]. The polymer can be deformed and fixed in a temporary shape by means of a thermomechanical cycle called programming. The programming includes heating up the material to a high temperature (Thigh), stretching it into a εmax or σmax and cooling it down to a low temperature (Tlow) in order to fix the temporary shape.

The programming can be performed in a stress-controlled or strain-controlled mode. The thermomechanical conditions of the programming affect the shape memory properties in a different way at each mode of the programming. One of the parameters which significantly affects shape recovery in a stress-controlled test is the holding time (th) at Thigh. This paper studies how the holding time under different levels of stress affects the shape memory properties.