Surface treatment of carbon microfibers

Abstract

A method of oxidizing the surface of carbon microfibers that includes contacting the microfibers with an oxidizing agent that includes sulfuric acid and potassiaum chlorate under reaction conditions sufficient to oxidize the surface. The invention also features a method of decreasing the length of carbon microfibers that includes contacting the microfibers with an oxidizing agent under reaction conditions sufficient to decrease the length.

1 - 19 . (cancelled).  
     
     
         20 . A method for decreasing the length of carbon fibrils comprising contacting carbon fibrils with an oxidizing solution under reaction conditions until the length of the carbon fibrils is decreased, 
 said carbon fibrils having a diameter less than 1 micron, having graphitic layers substantially parallel to the fibril axis, and being substantially free of a continuous thermal carbon overcoat, wherein the length of the projection of the graphitic layers on the fibril axis extends along the axis for a distance of at least two fibril diameters.    
     
     
         21 . The method of  claim 20  wherein said oxidizing solution comprises at least two oxidizing agents.  
     
     
         22 . The method of  claim 20  wherein the diameter of said carbon fibrils is less than about 0.1 micron.  
     
     
         23 . The method of  claim 20  wherein the diameter of said carbon fibrils is between about 3.5 and 75 nanometers.  
     
     
         24 . The method of  claim 20  wherein the fibrils are contacted with said oxidizing solution until the length of said fibrils is less than about 5 micron.  
     
     
         25 . The method of  claim 20  wherein the fibrils are contacted with said oxidizing solution until the length of said fibrils is between about 0.2 and 5 micron.  
     
     
         26 . The method of  claim 20 , further comprising the steps of: 
 filtering out said fibrils; and    washing said fibrils with deionized water and methanol.    
     
     
         27 . The method of  claim 26 , further comprising the steps of: 
 drying said fibrils under vacuum and under flowing nitrogen.