The amount of swelling or dilation can be illustrated by the pressure-volume-temperature (PVT) properties of the polymer-gas mixture. In polymer foam processing, cell nucleation and growth are governed by physical thermodynamic properties such as solubility, diffusivity, and surface tension. However, the determination of the sample's properties typically relies on the PVT data. The obtained data from PVT could help to analyze the amount of swelling and blowing agent's solubility and diffusivity in the polymer melt. On the other hand, the relationship between interfacial tension and foaming is of specific interest, as foaming is strongly influenced by the polymer's surface tension. Due to the main two reasons of polylactide's (PLA's) low melt strength and slow crystallization kinetics, PLA possesses poor foamability, and hence studying and understanding the PLA-gas mixtures' physical thermodynamic properties such as PVT behavior, solubility, and interfacial tension is of the great importance.