Abstract: The invention relates to a process of making articles of foamed polymethyl methacrylate (PMMA). In a first process stage a mixture comprising monomeric methyl methacrylate, plasticizer, preferably liquid foaming agent and catalyst is polymerized by heating and/or irradiation to form a foaming agent-containing solid body. In the second process stage this body is foamed by heating to the softening temperature of the plastic material. Either of these stages may also be performed continuously. The final product is clear-transparent and has large closed cells, a smooth surface, is light- and weather-resistant, readily workable, has good thermal insulation properties also in combination with plastics or glass coatings and may be used in a variety of applications, especially as a transparent insulating slab or plate.

Abstract: The present invention relates to processes of producing transparent foamed plastics, particularly foamed acrylate and methacrylate materials, in the form of e.g. panels, molded articles, or as cores for laminate bodies. Solid beads of transparent polymer material and containing a blowing agent are mixed with a reaction resin, softened by heating or swelling, and expanded to large pore size. During the blowing the beads may be displaced relative to one another. Subsequently the reaction resin is completely polymerized. The so obtained foamed plastics panels, which have large closed cells with contiguous faces and a smooth, non-porous surface, are particularly useful as insulating and building material exhibiting good transparency and protection against loss of heat, especially for greenhouses.