Abstract: A plastic foam article 1 produced by extrusion, for example, a plastic foam sheet comprising homopolymers and copolymers of polycyclic olefins, contains at least 10% by volume of open cells 2, 4 which have a polyhedron-like shape and adjoin one another. The deformation-free opening of the cells is brought about by means of an extrusion temperature higher than that for the extrusion of thermoplastic plastic foam articles having a closed-cell structure. This leaves webs 3 of cell walls 5, 6 intact in terms of shape, whether they now have openings 7 or have no through passages, so that the mechanical strength of the cell framework or the three-dimensional matrix is retained.

Abstract: A molded structure 1 produced by extrusion, such as an expanded plastic foam, a sheet, a profile or the like, contains at least 10% by volume of open cells 2, 4 which have a polyhedron-like shape and are adjacent to one another. A higher temperature during the extrusion in comparison with the extrusion of thermoplastic molded structures having a closed-cell structure results in deformation-free opening of the cells. Webs 3 of cell walls 5, 6 remain intact in shape whether they have orifices 7 or no passages, so that the mechanical strength of the cell skeleton or of the space matrix is retained.