Morphology Evolution of the Microcellular Polymethyl Methacrylate with Supercritical CO2: Effects of Shear Stress and Orthogonal Vibration

This study presents a foaming system that was developed to generate shear stress as well as oscillatory mechanical vibration in an orthogonal direction. The microcellular processes of PMMA specimens blown with ScCO₂ have been conducted to find the optimal processing parameters under the static conditions as well as dynamic conditions. It is evident that the cells are drawn into elliptical geometries sheared circumferential by the rotor rotation in isolation. However, the orthogonal pulsatile axial vibration superimposed on the polymer melt synchronously drives the oriented and elongated cells to isotropy as well as a more homogenous cells distribution and planar structure.