Physical properties of microcellular polymeric foams with supercritical CO₂

Microcellular polymeric foams possess characteristics of thermal insulation and lightweight and impact resistant in comparison to their solid counterparts. The physical properties (i.e. glass transition temperature and CO₂ solubility and diffusivity) of CO₂-polymer mixtures play important roles in determining microcellular foaming parameters, and subsequently affect cell diameter and density. In this paper, an evaluation of the current state of understanding of the physical properties of microcellular foaming process was reviewed. The effects of these three physical properties on foaming were explained. In addition, this study focused on visual measurement and the prediction of these three properties. For measurement, visual observation at high pressure is of great significance, providing a reference for further study.