A novel method for preparation of microcellular foams via in-situ generation of supercritical CO2

Microcellular foams are a new class of materials which contain gas bubbles of diameters on the order of 10 μm and have attracted much attention due to their enhanced propertiescompared with conventional plastic foams [1, 2]. The basic processing method for all microcellular foams is the use ofthermodynamic instability phenomena. A large amount of gas, typically CO2 or N2, is dissolved in the plastics under high pressure at the processing temperature so as to create a drivingforce for phase separation when the pressure is suddenly lowered. However, these processing methods because of theneed to a separate gas vessel and a high-pressure pump in order to provide super critical fluids are rather expensive. Inthis article, we introduce a novel and inexpensive technique for the production of microcellular PMMA foams based on insitu generation of supercritical CO2 from dry ice. Furthermore,effects of the process conditions i.e., the saturation temperature and pressure on the cell size and cell density of the foamed plastic have been investigated.