Method of producing a foamed polymer

Abstract From the Canadian patent

A process for producing a foamed polymer particularly, a foamed polyofefin, of highly uniform low density. A mixture of a polymer-forming material a, cross-linking agent, and a blowing agent is placed in a mould and reacted. This reaction product is cooled until the differential temperature between core and surface is below a predetermined maximum and removed, from the mould. The cooled product is then subjected to dielectric heating, preferably by microwave irradiation to cause, uniform heating and highly uniform expansion to produce a foamed polymer of highly uniform low density. The process of the invention enables production of relatively thick foamed polymers with a uniformity of …