Abstract: A method of rotationally molding hollow articles from cross-linkable polymeric material wherein the mold and molding material are simultaneously revolved about two nonparallel axes while being heated to fuse and cross-link polymeric material. When the polymeric material is partially cross-linked the mold containing the hollow article is opened at at least one location to admit heated air circulated therethrough to facilitate cross-linking of the inner portion of the molded tubular article and produce a smooth inner surface therein. Also disclosed is apparatus for performing the molding method of the invention.

Abstract: A method of rotationally molding hollow articles from cross-linkable polymeric material wherein the mold and molding material are simultaneously revolved about two nonparallel axes while being heated to fuse and cross-link polymeric material. When the polymeric material is partially cross-linked the mold containing the hollow article is opened at at least one location to admit heated air circulated therethrough to facilitate cross-linking of the inner portion of the molded tubular article and produce a smooth inner surface therein. Also disclosed is apparatus for performing the molding method of the invention.

Abstract: A pipe tee comprises a substrate having deposited thereon a reinforcing wrapping of a resin-impregnated filament.

Abstract: A mold apparatus for forming a molded article comprising a hollow body of a crosslinked polymer rotationally molded around a section of at least one piece of non-crosslinked conduit, which conduits protrude from said hollow body, made by attaching said conduits of non-crosslinked material at the desired location to the mold with said section being located inside a heated section of the mold so that the crosslinkable polymer during a rotational molding process is fused and crosslinked inside of the mold and around and in tight welding-type connection with said section, whereas the remainder of the piece or pieces of uncrosslinked polymer are heat-insulated, thus avoiding deformation or collapsing of these pieces.

Abstract: An insert that is to be embedded in a molded object is attached inside the mold in a resilient manner so that stresses caused in the area of the molded article surrounding the insert due to shifting of the molded article during cooling can be minimized.

Abstract: A molded article comprising a hollow body of a crosslinked polymer rotationally molded around a section of at least one piece of non-crosslinked conduit, which conduits protrude from said hollow body, made by attaching said conduits of non-crosslinked material at the desired location to the mold with said section being located inside a heated section of the mold so that the crosslinkable polymer during a rotational molding process is fused and crosslinked inside of the mold and around and in tight welding-type connection with said section, whereas the remainder of the piece or pieces of uncrosslinked polymer are heat-insulated, thus avoiding deformation or collapsing of these pieces.

Abstract: A pipe connection is provided which comprises two pipe ends, one inserted inside of the other, and one consisting essentially of crosslinked polymer material, whereas the other consists essentially of crosslinked or non-crosslinked polymer material, the connection having a layer of polymer material press-fitted and crosslinked between the two pipe ends. The pipe fitting is made by arranging the two pipe ends so that one is inserted in the other, one of the ends having a mechanical memory and having been deformed so that one of the pipe ends fits into the other, providing an in situ heat-crosslinkable polymer layer between the two pipe ends and heating the thus assembled pipe ends to crosslink the heat-crosslinkable layer, while the deformed pipe end returns towards its original shape, thus press-fitting the crosslinking polymer layer between the two pipe ends and making a strong, fluid-tight joint.

Abstract: A mandrel and bushing sizing die assembly has an annulus formed between the mandrel and the bushing of the assembly for passing plastic material therethrough and forming a thick-walled tubular product. A middle portion of the annulus has a thickness in the range of about 25-50 percent of the greatest thickness of a first end portion of the annulus and the second, discharge end of the annulus has a thickness greater than about 1/4-inch and greater than the thickness of the middle portion of the annulus.

Abstract: An improved method for the production of an extrudate of poly(phenylene sulfide) and filler with the resulting extrudate having a stiffness of less than 10,000 psi as determined by ASTM D747-70. The extrudate formed is very flexible. The method includes the step of applying pressure to a heated mixture of poly(phenylene sulfide) and filler and flowing the mixture through a first orifice into an expansion chamber and out of the expansion chamber through a second orifice. The extrudate exiting the second orifice is extruded into the atmosphere or into a mold cavity for the molding of a piece part. The resulting extrudate is flexible and can be used as a packing or gasket material.

Abstract: Method of making a molded article comprising a hollow body of a crosslinked polymer rotationally molded around a section of at least one piece of non-crosslinked conduit, which conduits protrude from said hollow body, made by attaching said conduits of non-crosslinked material at the desired location to the mold with said section being located inside a heated section of the mold so that the crosslinkable polymer during a rotational molding process is fused and crosslinked inside of the mold and around and in tight welding-type connection with said section, whereas the remainder of the piece or pieces of uncrosslinked polymer are heat-insulated, thus avoiding deformation or collapsing of these pieces.

Abstract: A process for reforming a crosslinked thermoplastic article is described which comprises forming a crosslinkable polymer containing a crosslinking agent into a first shaped article, and thereafter reforming the first shaped article into a second shaped article. An improved material handling process is also described which comprises the optional employment of the first or second or any subsequently shaped article in the form of a container. The containers can be reformed into various shapes by suitably regulating the reforming temperature conditions.

Abstract: A mandrel and bushing sizing die assembly has an annulus formed between the mandrel and the bushing of the assembly for passing plastic material therethrough and forming a thick-walled tubular product. A middle portion of the annulus has a thickness in the range of about 25-50 percent of the greatest thickness of a first end portion of the annulus and the second, discharge end of the annulus has a thickness greater than about 1/4-inch and greater than the thickness of the middle portion of the annulus.

Abstract: A hollow multilayered article is rotationally molded by introducing into the mold particles of a hompolymer or copolymer of ethylene containing a crosslinking agent and heating the mold during rotation thereof to melt this first polymeric layer. Solid particles of a different polymer are then introduced into the mold at a time after at least substantially all of the particles of the first polymer have melted and prior to the time when the inner surface of the first layer would become smooth and glossy. The mold is then rotated and heated to melt the second polymer. The mold is then cooled and the multilayered article removed.