Quantitative morphology analysis of polymers foamed with supercritical carbon dioxide using Voronoi diagrams

Porous polymeric materials have a good impact strength, light weight and high porosity. Therefore, these foams are used in a wide range of applications, including insulation, separation processes and packaging. Since it is important to have an objective comparison of polymeric foams, this paper discusses a quantitative method using Voronoi diagrams, which has been developed to analyze and compare different morphologies of polymers foamed with supercritical carbon dioxide, based on the average cell area, cell area distribution and homogeneity. In contrast to SEM analysis only, different foam morphologies can be compared with this technique in an objective manner. The analysis is based on the centers of the cells and is therefore to a large extent independent of the sample preparation. Using the Voronoi-approach, it is possible to extrapolate the 2D view of the SEM picture to a 3D representation of the foam with the thickness of one cell layer.