| 摘要 |
A shaped, foamed, cellular thermoplastic article is made by entraining granules of an expandable thermoplastic material in a heated gaseous medium, flowing said entrainment into a space that defines the shape of said article while heating said granules to a temperature above the softening point of the thermoplastic material but below the temperature where substantial expansion takes place as the granules flow to said space, thereafter subjecting said granules in said space to a vacuum so that said granules expand and fuse together to form a cellular plastic article conforming to said space and then removing the article from said space. Expandable polymers used include homo- and co-polymers derived from vinyl monomers including styrene, vinyl chloride, divinyl benzene, a -methyl styrene, nuclear dimethyl styrenes and vinyl naphthalene. Particularly useful polymers are polystyrene and its copolymers with butadiene, a -methyl styrene, divinyl benzene, isobutylene and acrylonitrile. |
