Properties and mechanism of two-way shape memory polyurethane composites

Recently, smart materials have drawn wide attention from many researchers. In this paper, laminated shape memory polymer composite (SMPC) exhibiting two-way shape memory effect (SME) has been prepared by combining the pre-elongated shape memory polyurethane (SMPU) with the un-elongated elastic polyurethane (PU). Then the shape memory behaviors, laminated structure and two-way SME mechanism are investigated systematically. The results show that two-way shape memory behaviors, i.e., bending upon heating and reverse bending upon cooling, are achieved in the resulted SMPU-based-SMPCs. In addition, the SMPCs show the compositive thermal properties and dynamic mechanical properties due to their physical combination of layer-by-layer. Furthermore, the shape memory mechanism can be ascribed to the reversible change of two forces, i.e., recovery force in the SMPU layer and bending force in the elastic PU layer. (C) 2010 Elsevier Ltd. All rights reserved.