Abstract: Tubular workpieces of oriented polymers such as polyethylene polyester and PVC are formed by drawing a workpiece over an expanding former in the absence of any force perpendicular to the axis of the workpiece. The processes do not require the use of any liquid lubricant. They enable greater degrees of expansion and hence orientation in the direction perpendicular to the axis to be achieved and result in products of improved appearance and strength.

Abstract: Tubular workpieces of oriented polymers such as polyethylene polyester and PVC are formed by drawing a workpiece over an expanding former in the absence of any force perpendicular to the axis of the workpiece. The processes do not require the use of any liquid lubricant. They enable greater degrees of expansion and hence orientation in the direction perpendicular to the axis to be achieved and result in products of improved appearance and strength.

Abstract: Tubular workpieces of oriented polymers such as polyethylene polyester and PVC are formed by drawing a workpiece over an expanding former in the absence of any force perpendicular to the axis of the workpiece. The processes do not require the use of any liquid lubricant. They enable greater degrees of expansion and hence orientation in the direction perpendicular to the axis to be achieved and result in products of improved appearance and strength.

Abstract: A process for the solid phase deformation of orientable, semi-crystalline, thermoplastic, polymeric material, in particular polyethylene, is provided in which an improvement of the mechanical properties of the polyethylene is achieved. The process for producing a product from linear polyethylene includes forming a workpiece which is to be extruded in the solid phase by consolidating a mass of solid particulate linear polyethylene under heat and pressure. The resulting workpiece is subjected to heat treatment under pressure to cause the polyethylene to crystallize in an extended chain morphology and to have a melting point of at least 139.5.degree. C. and a density of at least 0.98 g/cm.sup.3. Thereafter the workpiece of polyethylene is deformed in the solid phase to provide a polyethylene product by, for example, passage through a die, the workpiece being subjected to a deformation extrusion ratio of at least 3 and preferably 3 to 25.