Spatial control of additives by high temperature

Abstract

Provided is a method of making a polymeric material with a spatially controlled distribution of one or more additives including the steps of blending the one or more additives with a polymeric material, consolidating the polymeric material, heating at least a portion of at least one surface of the consolidated additive-blended polymeric material, and cooling the heated consolidated additive-blended polymeric material, thereby forming a polymeric material with a spatially controlled distribution of additive.

What is claimed is: 
     
         1 . A method of making an additive-doped polymeric material, the method comprising:
 (a) doping a consolidated polymeric material with at least one additive by diffusion to form a consolidated additive-doped polymeric material;   (b) heating at least a portion of at least one surface of the additive-doped polymeric material to form a heated consolidated additive-doped polymeric material; and   (c) cooling the heated consolidated additive-doped polymeric material to form a cooled consolidated additive-doped polymeric material, thereby forming a polymeric material with a spatially controlled distribution of additive.   
     
     
         2 . The method of  claim 1 , wherein step (a) further comprises consolidating a polymeric material to form the consolidated polymeric material before doping the consolidated polymeric material. 
     
     
         3 . The method of  claim 2 , wherein the polymeric material is selected from an extrudate, pellets, a resin powder, flakes, a liquid, or a gel. 
     
     
         4 . The method of  claim 2 , wherein consolidating the polymeric material comprises at least one of compression molding, ram extrusion, extrusion, hot or cold isostatic pressing, injection molding, and direct compression molding. 
     
     
         5 . The method of  claim 2 , wherein step (a) further comprises blending the polymeric material with at least one additional additive before consolidating the polymeric material. 
     
     
         6 . The method of  claim 5 , wherein the at least one additional additive is selected from an antioxidant, vitamin E, and an anti-cross-linking agent. 
     
     
         7 . The method of  claim 1 , wherein step (a) further comprises consolidating a polymeric material to form the consolidated polymeric material and machining the consolidated polymeric material before doping the consolidated polymeric material. 
     
     
         8 . The method of  claim 1 , wherein step (c) further comprises irradiating the cooled consolidated additive-doped polymeric material. 
     
     
         9 . The method of  claim 8 , wherein step (c) further comprises annealing the cooled consolidated additive-doped polymeric material after it has been irradiated. 
     
     
         10 . The method of  claim 1 , wherein step (c) further comprises machining the cooled consolidated additive-doped polymeric material. 
     
     
         11 . The method of  claim 1 , wherein step (c) further comprises machining the cooled consolidated additive-doped polymeric material and thereafter irradiating the cooled consolidated additive-doped polymeric material. 
     
     
         12 . The method of  claim 1 , wherein steps (a) and (b) are concurrent. 
     
     
         13 . The method of  claim 1 , wherein the at least one additive is selected from an antioxidant, vitamin E, and an anti-cross-linking agent. 
     
     
         14 . The method of  claim 1 , wherein step (b) further comprises masking at least one of the surfaces of the material before heating at least a portion of at least one surface of the consolidated additive-doped polymeric material, thereby preventing extraction. 
     
     
         15 . The method of  claim 14 , wherein step (b) further comprises using a masking material for masking at least one of the surfaces of the material, the masking material being a metal. 
     
     
         16 . The method of  claim 1 , wherein step (b) further comprises heating in the presence of at least one of an inert gas, a non-inert gas, air, a vacuum, a liquid, a liquid with gas bubbled through, a liquid saturated with gas, a supercritical fluid, a convection current, and combinations thereof. 
     
     
         17 . The method of  claim 1 , wherein step (a) further comprises using a doping source for doping the consolidated polymeric material, the doping source being selected from blended polyethylene with at least one antioxidant, polyethylene doped with at least one antioxidant via diffusion, at least one free antioxidant, porous ceramic doped with at least one antioxidant via diffusion, porous polyethylene doped with at least one antioxidant via diffusion, and porous polytetrafluoroethylene doped with at least one antioxidant via diffusion. 
     
     
         18 . The method of  claim 1 , wherein step (b) further comprises extracting the polymeric material from the consolidated additive-doped polymeric material prior to heating the consolidated additive-doped polymeric material. 
     
     
         19 . The method of  claim 1 , wherein step (b) further comprises extracting the polymeric material from the heated consolidated additive-doped polymeric material. 
     
     
         20 . The method of  claim 18 , wherein the step of extracting comprises at least one of a liquid, gas and fluid extraction.