Polyamide 12: Carbon Nanotube Composite Material Under the Aspect of Future Application as Balloon Catheter Material

Balloon catheters are a common tool used in modern microvasive surgery like angioplasty. A problem during balloon dilatation is longitudinal growth, because of the danger of lesions due to shearing forces. Therefore a modified composite material with anisotropic mechanical properties, which rather inflates radially than longitudinally, would be interesting for the application in balloon catheter manufacturing. Multi-walled carbon nanotubes (MWNTs) represent a nanomaterial with a high aspect ratio tubular crystal structure with diameters in the nanometer range and fiber lengths typically in the range of a few microns. They exhibit high elasticity in combination with high mechanical strength and therefore represent an interesting material for the anisotropic reinforcement of polymer-based composite thin films. Therefore we first simulated the micromechanical properties of Polyamide 12-MWNT composite material variants by variation of MWNT concentration and nanofiber alignment with the semi-analytical mean field method. Then in a second step we performed experimental studies, in which we processed commercial Polyamide 12-MWNT composite masterbatch material by extrusion and fabricated tensile test specimens via injection molding and blow film extrusion. The specimens were finally tested in uniaxial tensile tests and the performance of mechanical reinforcement with regard to elastic moduli and yield point was evaluated. Although our results show, that already relative low amounts of MWNTs do have a considerable influence on the mechanical properties of composite materials and anisotropy of blown films, other technological processing strategies than pure melt mixing by extrusion, which may lead to a better interfacial bonding between the carbon nanotubes and the polymer matrix should be considered.