Micro-blow molding: Designing of an angioplasty balloon

Abstract

Angioplasty balloons are used to enlarge narrowed blood vessels; the balloons are required to have thin walls, and yet high burst pressure, and also be semi-compliant (e.g., limited increase in balloon diameter past the nominal pressure). In this study, the 3 X15 mm and 8X30 mm balloons are formed by a unique micro-blow molding process. The process starts by stretching an extruded tubing of thermoplastic elastomer, into a 'parison' by means of a Double End Stretching Machine. The balloon forming is accomplished through a process called stretch blow molding, where the 'parison' is stretched under pressure and at elevated temperatures to form a 'balloon'. Following the formation of the balloon, a secondary temperature is applied over a dwell time; this annealing step prevents shrinkage of the balloon once it is removed from the mould. The current study focuses on the effects of heat treatment during micro blow molding process to achieve semi-compliant balloons with thin walls and high burst pressure. To this end, the balloons prepared under different processing conditions are characterized in terms of mechanical properties. An ideal process condition is proposed