Producing thermoplastic articles, particularly with porous walls.

摘要

An article is molded from a thermoplastic material matrix having a particulate filler distributed throughout the matrix. The article is then expanded to develop fissures between the thermoplastic matrix material and particles of the filler material, so as to render the article porous. Apparatus for expanding a pipe from the inside or expanding the sides of corrugations in a pipe are also disclosed.