Recent investigations demonstrated that while, in carbon dioxide, melting transitions are lowered, in nitrogen, this is not always the case, and frequently, instead of reduction, an increase is observed. This difference has been attributed to differences in the extent of diluent versus hydrostatic effects in carbon dioxide versus nitrogen. The outcome is often attributed to lower solubility of nitrogen in many polymers.
To bring clarity to the effect of sorption and swelling of carbon dioxide and nitrogen and linking it to the changes in melting temperatures, we have been conducting comparative evaluations using a magnetic suspension balance, equipped with a view-cell and a digital camera for experimental assessment of swelling for accurate determinations of sorption. In this presentation, we will compare the observations in a semicrystalline polymer (polycaprolactone) and rubbery polymer (ethylene octene copolymer).