This work is aimed at studying the foaming behavior of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HHP) with supercritical carbon dioxide (scCO2). We investigated the foam’s cell structure and property in different operation condition.
In this study，first we change the operation conditions just like foaming pressure (15MPa~35MPa)、foaming temperature (120℃~130℃) and saturation time (15min~60min). Then we use scanning electron microscope (SEM) to observe the cell structure, and use DSC (Differential Scanning Calorimetry) to measurement the melting point and enthalpy of the polymer foam. Finally we use the formula to calculate the cell diameter 、cell density and crystallinity of polymer.
In foam’s cell structure, we find that, the cell size will increase with the increase temperature, but the cell density will decrease. The cell size will decrease with the increase pressure, but the cell density will increase. Finally, we find that, the saturation time with minimal impact on the cell structure. However, in the physical properties, we find that, PVDF-HFP foam’s melting temperature will increase with increase foaming pressure and foaming temperature, but crystallinity will decrease. Finally we find that, the saturation time will cause greater effect in physical properties only in some operating conditions.
