Low-durometer polymers often are used to manufacture catheters and medical tubing because they afford flexibility to the physician who is navigating the device through the vasculature while minimizing patient trauma. However, the material's inherent friction can lead to manufacturing and packaging issues and create complications in the final application. Innovative Polymer Compounds (IPC; Kilbeggan, Ireland) has developed a material based on a medical-grade polyether block amide from Arkema, Pebax MED, that improves lubricity and adds functionality. IPC will showcase the material at the forthcoming MEDTEC Europe event in Stuttgart, Germany.
"Materials with a low Shore hardness tend to have tackiness issues," David Howard, IPC Marketing Director, told PlasticsToday. "We tweaked the formulation of Pebax in terms of lubricity and, to some extent, conductivity." This was achieved by adding a nano additive to the material, called PEBASlide, that resulted in a measurable improvement in the coefficient of friction.
The additive significantly lowered the dynamic coefficient of friction on dry samples and on samples lubricated with a 40%-wt aqueous glycerol solution to mimic the viscosity of blood, says Howard. A 36% reduction in coefficient of friction was achieved using material prepared with a low loading of the nano-additive per ISO 8295/ASTM 1894 test methods. By adding a hydrophilic Pebax grade, the coefficient of friction was reduced even further to 55% below the virgin resin. The improvement in coefficient of friction was observed in a variety of samples including flat test plaques, extruded tape, and tubing, according to Howard. Moreover, samples prepared using this new formulation had good dimensional stability; the percentage change in weight and dimensions remained low when measured at 37°C over 24 hours.