A Novel Process to Create Arbitrary Microcellular Patterns in Polycarbonate using a Laser Beam

Abstract

Microcellular and nanocellular polymer foams offer a wide range of applications from food safety to aerospace industries. In this work, we introduce a versatile process to nucleate microcells in polycarbonate sheets via laser beam. This method allows local heating of CO2 saturated polycarbonates which results in the creation of arbitrary shapes of microcellular foamed regions in a plastic part. We present the processing parameters required to create foams in polycarbonate sheets that were saturated with carbon dioxide at pressures of 1, 3 and 5 MPa. The relationship between the processing (input) factors of speed, power (of the laser beam), and the saturation pressure and the consequent microstructure produced (parameters like average cell size, foam depth, and melted surface thickness) is investigated. Energy delivered by the laser and the temperature rise at the surface of the specimen is also approximated. The feasibility of this process is also demonstrated on PEI. High resolution patterns of microcellular foams were directly written by a laser beam which shows the extraordinary level of control offered by this methodology. Intricate 2D digital designs are also produced using this novel approach.