Surface engineering of shape memory alloy/polymer-composites: Improvement of the adhesion between polymers and pseudoelastic shape memory alloys

In recent years, pseudoelastic applications of NiTi shape memory alloys have received considerable attention in the medical field due to the development of medical devices and implants. For such applications it can be beneficial to consider hybrid systems like polymer-coated shape memory metals. The objective of the present work is to show that surface treatments can strongly improve adhesion between a pseudoelastic NiTi shape memory ribbon and polyamide (PA6). In our study a pseudoelastic shape memory ribbon was subjected to different kinds of surface treatments, including mechanical, chemical and physical processing steps. We use injection moulding to produce a composite, consisting of a central NiTi ribbon half of which is fully contained in polyamide. Then, pull-out experiments are performed to characterize the adhesion of the NiTi ribbon in the polymer matrix. We investigate if depending on the surface condition, pull-out stresses can vary.