Study on the Variation in Mechanical Performance of Medical Balloons depending on Polymer Tube Extrusion Process Variables

Balloon catheters are a key technology in medical devices, essential for minimally invasive procedures. This study quantitatively analyzes how the orientation characteristics of polymer tubes, influenced by extrusion conditions, affect the mechanical properties and compliance of the final balloon—where compliance refers to the change in diameter under external pressure. Nylon 12 tubes, with a target outer diameter of 1.2 mm and an inner diameter of 1.0 mm, were extruded under six different orientation conditions by varying the screw flow rate and puller speed. The tubes were processed under identical forming conditions, allowing for a consistent evaluation of their mechanical properties. As orientation increased, elongation decreased while yield strength increased, and these trends continued in the balloon, significantly influencing compliance. To quantitatively measure orientation, we introduced the dimensionless Deborah number. We established a curve-fitted experimental model that links extrusion conditions, polymer tube properties, and balloon compliance. This model allows for the prediction of balloon performance based on extrusion-stage parameters, providing a practical framework for process optimization. Overall, this study offers an effective quantitative indicator for forecasting balloon catheter performance based on extrusion conditions and supports the systematic design of medical balloon products.