Method and apparatus for extruding foam polymeric materials involving the use of an extrusion screw having spaced multiple flight mixing means thereon

摘要

Cellular chlorinated polyvinyl chloride resin is made in an extruder that is characterized by a combination of multiple flights and a plurality of open slots in the mixing section to facilitate mixing of the resin and a blowing agent whereby a rigid thermoplastic cellular product of low density is made that has a predominantly closed cell structure.