Improved adhesion of NiTi wire to silicone matrix for smart composite medical applications

Recent uses of intelligent composites in biomedical appliances aggrandize the necessity of bonding-strength improvement in NiTi/silicone matrix interface. SEM micrographs and pull-out tests are employed to determine the strength of the NiTi/silicone bonds in a flexible composite piece. Greater adhesion strengths are obtained due to the presence of thin oxide layer, surface roughness and frictional forces between the embedded-wires and the contacting phase. Effect of curing treatment on phase transformation temperatures of the wires is determined by electrical resistivity (ER) measurements. Results show that the curing treatment shifts the transition points of the wires towards higher temperatures at the heating and lower temperatures at the cooling try-outs, respectively. These changes affect the shape memory behavior of the NiTi wires embedded within the biocompatible flexible composite segments. (C) 2009 Elsevier Ltd. All rights reserved.