Editors : K. Gall, T. Ikeda, P. Shastri, A. Lendlein
a1 email@example.com, Center for Biomaterial Development, Institute of Polymer Research, GKSS Research Center Geesthacht GmbH and Berlin-Brandenburg-Center for Regenerative Therapies (BCRT), PBI, Kantstrasse 55, 14513 Teltow, Germany, Teltow, 14513, Germany, +49 (0) 3328 352 328, +49 (0) 3328 352 452
a2 firstname.lastname@example.org, Center for Biomaterial Development, Institute of Polymer Research, GKSS Research Center Geesthacht GmbH, PBI, Teltow, Germany
a3 email@example.com, Institute of Polymer Research, GKSS Research Center, Teltow, Germany
Biocompatible shape-memory polymers are of high significance for application in medical devices or instruments for minimally invasive surgery. To follow the medical device placement or changes in shape of the device in vivo by imaging methods like X-ray techniques, radiopacity of the polymer is required. In this work, we explored the shape-memory properties of radiopaque polymer composites prepared by incorporation of barium sulphate micro-particles in a biomedical grade polyether urethane (PEU) by co-extrusion technique. The filler content was varied from 5 wt% to 40 wt%, which was confirmed by thermal gravimetric analysis (TGA) measurements, while the particle distribution was visualized by scanning electron microscopy (SEM). The thermal and mechanical properties of the composites were investigated by means of dynamic mechanical analysis at varied temperature (DMTA) and tensile tests. The shape-memory properties of PEU composites were quantified in cyclic, thermomechanical experiments. A significant increase in Young’s modulus and a decrease in elongation at break were observed for PEU composites with increasing content of BaSO4, while the DMTA results were not affected by incorporation of the fillers. All samples exhibited excellent shape-memory properties with shape fixity rates (Rf) above 98% and values for shape recovery rate (Rr) in the range of 81% to 93%. The maximum stress (σmax) obtained under constant strain recovery conditions increased from 0.6 MPa to 1.4 MPa with raising amount of BaSO4, while the corresponding temperature (Tσ,max) as well as the switching temperature (Tsw) determined under stress-free conditions remained constant for all polymer composites.
(Received April 06 2009)
(Accepted August 06 2009)