The properties of solid or tubular thermoplastic profiles are enhanced using pressure orientation of the molecular structure. Part-crystalline polymer is extruded and undergoes orientation of the polymer chains through stretching flow. During extrudate solidification further molecular orientation is produced by applying a pressure three dimensionally onto the surface of the extrudate at a uniform temp.. Appts. comprises a one piece tool connected to the extruder die and having integral drive units running either towards and/or with the extrudate movement. The drive units make radial contact with the extrudate surface. USE/ADVANTAGE - The process and appts. produce solid or tubular thermoplastic profiles with improved properties in the non-axial direction
