Design of a Novel Extrusion System for Manufacturing Microcellular Polymer

Abstract

The described system for the production of microcellular hollow fibre is based on the thermic extrusion of polymers under addition of CO₂ as a blowing agent by means of pressure build-up and drop-off. The design of a novel extrusion system is presented according to this concept, which involves a modular configured co-rotating twin screw extruder, a gear melt pump and a designed die. The gear melt pump works as barrier between the extruder and the extruding head and allows to adjust the pressure over a wide range. The pressure level reached is dependent on the screw speed of the gear melt pump and the resistance of the polymer melt in the extruding head. To initiate the cell nucleation a die was used to lower the pressure. Microcellular foams have been successfully produced using this system.