Physical ageing of a PU-based shape memory polymer: Influence on their applicability to the development of medical devices

The variation in the properties of polymeric materials through ageing has considerable implications, since it affects the performance of any associated devices. Specially in the case of implantable devices with shape memory, any change in the switching temperature can give rise to problems in the thermal activation of the geometrical changes necessary to treat certain pathologies. This paper presents a study about the physical ageing of a polyurethane based shape memory polymer, SMP, at different temperatures using differential scanning calorimetry, DSC, and microhardness, MH, tests. The benefits of the combinated application of both testing techniques is shown, since DSC tests give information on the evolution of the glass transition temperature and the MH tests provide details of changes regarding mechanical properties. (c) 2008 Elsevier Ltd. All rights reserved.