Glass transition of PLA-CO2 mixtures after solid-state saturation

Polymer foams offer high sustainable performance in terms of their lightweight potential, insulation and high specific mechanical properties. The foaming of polymers depends on the properties of gas-laden solids or liquids. For foaming in the solid state, the foaming temperature must be higher than the glass transition temperature of the saturated polymer system. Moreover, the knowledge of sorption conditions and thermal properties is crucial for foam formation. In this study, the correlation between the glass transition temperature and the sorption conditions was investigated. This comparison was made by determining the sorption behavior for different pressure levels and the corresponding glass transition temperature using a high-pressure differential scanning calorimetry. The time, pressure and CO2 content were varied. For the first time, the Chow model could be verified for PLA with a coordination number of 3.