Morphology of irradiated PMMA membranes prepared by phase inversion with supercritical CO2

Poly(methyl methacrylate)(PMMA)pellets are irradiated using 60Co gamma-ray in air and successfully formed by hot pressing at constant conditions.The irradiated PMMA membranes are prepared by supercritical carbon dioxide(scCO2)as a physical blowing agent using the pressure quench method.Effects of foaming conditions such as adsorbed dose,saturation temperature,pressure on the morphology and cell size of the microcellular PMMA membranes are investigated in detail.The results showed that the irradiated PMMA membranes possess spherically closed-cell structure with uniform cell size.They have a high cell density compared with virgin PMMA.The cell size uniformity becomes poor at dose lower than 10 kGy,but increases with the dose at dose higher than 10 kGy.The mean cell diameter is less than 10μm and the cell density increases with increasing dose.The average cell size of irradiated PMMA membranes decreases and cell density increases with increased saturation temperature and pressure.The changes in morphology of membranes are attributed to the gamma-ray radiation and scCO2synergistic effect.