Effects of the die geometry on the expansion of polystyrene foams blown with carbon dioxide

This article presents the effects of the die geometry on the expansion ratio of extruded polystyrene foams blown With CO2. Three groups of interchangeable filamentary dies were used to represent the die parameters. The experimental results reveal that a strong relationship exists between the expansion ratio of the extruded polystyrene foams and the die geometry through its effects on the pressure-drop rate, the die pressure, the amount of premature cell growth, and the initial shape of the extrudate. (C) 2008 Wiley Periodicals, Inc.