Multi-shape memory effect in shape memory polymer composites

In this work, the multi shape memory effect is studied for two types of thermal active epoxy polymer composites. One of them is called the controlled behavior of composite material (CBCM) which has already been tested as an unsymmetrical active composite and the other one is the conventional symmetrical composite. The shape memory of these composites characterized by the value of the initial fixity is obtained through one-step programming cycle. During this cycle, the composites are heated to the fixity temperature above their thermal glass transition temperature. During the recovery step, by providing different lower recovery temperatures than the fixity temperature, the properties of multi-step positions are obtained. For a certain recovery temperature, the ability to conserve the corresponding positions is investigated for several cycles. For CBCM, contrary to symmetric composite, the coupling between its shape memory property and unsymmetrical constitution leads to a two-way bending actuator with two opposite positions. (C) 2012 Elsevier B.V. All rights reserved.