The present invention relates to a method of making cross-linked highly crystalline polymeric material comprising irradiating the polymeric material with ionizing radiation, thereby forming a cross-linked polymeric material, doping and pressuring the cross-linked polymeric material heating and cooling the pressurized cross-linked polymeric material, then releasing the pressure, thereby forming a highly crystalline cross-linked polymeric material. The invention also encompasses a cross-linked highly crystalline polymeric material for a medical device or implant made by the above method, and a medical device or implant produced by machining the cross-linked highly crystalline polymeric material.
