Batch-foaming of miscible, immiscible and compatibilized polymer blend
systems over a wide compositional range was carried out using carbon dioxide
as a physical blowing agent. The resulting foam morphology was characterized
by a detailed evaluation of foam density as well as of the cellular
parameters. With regard to multiphase blends, transmission electron
microscopic observations further provided a detailed insight into the cell
wall morphology. The role of the melt-elongational properties and of the
glass transition behavior of the various blend systems on the foaming
characteristics was systematically elucidated. While the miscible blends
showed a simple additivity behavior with regard to their foaming
characteristics and properties, a significant influence of the initial blend
morphology is demonstrated for the multiphase blends.