Effects of Operating Conditions during Three-Layered Polymeric Balloon Catheter Extrusion

Abstract

Multilayered balloon catheters are attracting more attention in recent years. Multilayered balloon catheters have some unique properties such as meso-/microscale dimensions, small wall thickness, and strict requirements of dimensional accuracy. In this study, three-layered polymeric balloon catheters composed of polyamide, ethylene vinyl acetate, and polypropylene (PA/EVA/PP) are successfully fabricated using a three-layered coextrusion die and the polymer melt flowing behavior through the extrusion die are analyzed. Both the diameter and wall thicknesses have been selected as the targeted structural parameters to investigate the effects of pulling speed, air injection volume rate, and screw speed on the quality of the extrudates. The optimal combination of these three operating conditions has been achieved. It is found that pulling speed can significantly affect the diameters of the extruded balloon catheters. The variation interval values of outer profile diameter and inner cavity diameter with the extrusion experiments are 20.95% and 13.04%, respectively. The screw speed of each layer has a great influence on the wall thickness of each layer. Through the influence of outer screw speed, middle screw speed and inner screw speed, the variation interval values for outer layer wall thickness, middle layer wall thickness, and inner layer wall thickness are 31.06%, 35.69%, and 31.35%, respectively. The air injection volume rate has negligible effect.