ScCO2 foaming made use of a high-pressure chamber integrating a control system allowing precise monitoring of the foaming parameters (SITEC Sieber Engineering AG, Switzerland). Specimens of the various materials (3g) were placed in cylindrical open molds of 24mm in diameter and inserted into the pressure vessel. The CO2 pressure and temperature were then increased to the final saturation temperature, Tsat, and saturation pressure, psat, which were maintained for a certain time, t, according to previous studies on PLA foaming.25,26 In the present case, psat was set to 200 bar for all the tests, and Tsat to 155C, 165C( t¼10 min) or 190C( t¼20 min) for the chain-extended materials. Cell nucleation and growth (foam expansion) were initiated by the thermodynamic instability created by depressurization. Depressurization rates, dp/dt, of 4bar/s and 14bar/s were used here. Stabilization of the foam structures resulted from cooling induced by the pressure release and maintained by the cooling system of the chamber. Figure 1 summarizes the foaming parameters used for the different materials. A minimum of five foams were prepared for each set of conditions and for each material.