Time-dependent plasticization behavior of polyimide membranes at supercritical conditions

The time-dependent CO2-induced plasticization behavior of glassy Matrimid® 5218 polymer membranes at supercritical conditions up to 120 bar was investigated. Glassy polyimide were conditioned with both gaseous CO2 and liquid-like sc-CO2. during permeation sorption correlated the intrinsic membrane properties fluid properties. In region concentration increased slightly over time, while in sc-CO2 remained constant time showed no hysteresis, indicating an induced glass transition. Contrary permeability more pronounced which increases feed pressure because plasticization. Despite strong time-dependency, independent region. This difference between is due presence a gradient experiments. addition, significant hysteresis. Exposure resulted highly plasticized changed all subsequent pressures, slow chain relaxation rates. Clearly, these relationships proof that history critical aspect for phenomena high pressures.