Mechanical anisotropy of PS/CO 2 microcellular foam sheet prepared by foaming extrusion

Abstract

Microcellular polystyrene foam sheets prepared by extrusion foaming with CO₂ as the blowing agent were found to exhibit a significant anisotropy in mechanical behavior which could not be explained solely by the shape anisotropy of the cells and/or the preferential orientation of polystyrene molecules in the machine direction. Surprisingly, samples allowed to fully relax were still found to maintain part of their mechanical anisotropy, which was attributed to the weakness of the cell walls perpendicular to machine direction.

Keywords

Microcellular foam polystyrene carbon dioxide mechanical anisotropy molecular orientation

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