Crosslinking of polyethylene for low wear using radiation and thermal treatments

Abstract

The present invention discloses methods for enhancing the wear-resistance of polymers, the resulting polymers, and in vivo implants made from such polymers. One aspect of this invention presents a method whereby a polymer is irradiated, preferably with gamma radiation, then thermally treated, such as by remelting of annealing. The resulting polymeric composition preferably has its most oxidized surface layer removed. Another aspect of the invention presents a general method for optimizing the wear resistance and desirable physical and/or chemical properties of a polymer by crosslinking and thermally treating it. The resulting polymeric compositions is wear-resistant and may be fabricated into an in vivo implant.

1 . A preformed polymeric composition comprising a crosslinked thermally treated polymer.  
     
     
         2 . The composition of  claim 1 , wherein the composition possesses one or more of the following characteristics: degree of swelling of between about 1.7 to about 5.3; molecular weight between crosslinks of between about 400 to about 8400 g/mol; and a gel content of between about 95 to about 99%.  
     
     
         3 . The composition of  claim 1 , wherein the preformed polymeric composition is crosslinked by gamma radiation at a dose from about 1 to about 100 Mrad.  
     
     
         4 . The composition of  claim 3 , wherein the dose is from about 5 to about 25 Mrad.  
     
     
         5 . An in vivo implant comprising a crosslinked and remelted polymer.  
     
     
         6  to  30 . (canceled).