Compressed N2 Research Articles

Effects of plasticization and hydrostatic pressure on tensile properties of PMMA under compressed carbon dioxide and nitrogen

ABSTRACTWe investigated the stress−strain behavior of PMMA films under compressed CO2 and N2. The elongation at break increased and the stress decreased with increasing CO2 pressure at pressures above 3 MPa, indicating that the tensile property changed from brittle to ductile under compressed CO2. In contrast, the material property became more brittle under compressed CO2 at pressures below 2 MPa and under compressed N2. By depressurizing the compressed gas and excluding the hydrostatic pressure, the property of the gas‐absorbed specimen changed from brittle to ductile. These results suggest that deformability by molecular orientation is enhanced by the plasticizing effect caused by a large amount of absorbed gas while it is suppressed by the effect of hydrostatic pressure caused by a small amount of absorbed gas. Conversely, the elastic modulus decreased under both compressed CO2 and N2, but the decrease under CO2 was much larger than that under N2, suggesting that distortion in the elastic region is dominated by the plasticization effect. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43431.