Measurement of the PVT property of PP/CO2 solution

The pressure–volume–temperature (PVT) data for polymer/gas solutions is an important fundamental property of which accurate measurement has not been reported until recently. The diffusivity, solubility and surface tension are critical physical properties of polymer/gas systems for understanding and controlling polymer processing such as foaming, blending, extraction reaction and so on. However, the determination of these properties relies on accurate PVT data as a prerequisite. In this study, we have developed a new methodology for measuring the PVT properties of polymer melts saturated with high-pressure gas at elevated temperatures. This paper presents a description of the methodology, including the experimental apparatus design and data analysis. A case study on neat polypropylene (PP) density measurement and determination of PP/CO2 solution volume swelling was presented to elucidate and verify the methodology at high-pressure and high-temperature conditions.