Graphite platelet nanostructures

Abstract

Separated graphite nanostructures are formed of thin graphite platelets having an aspect ratio of at least 1,500:1. The platelets have an angular geometric structure and may be fully independent from an original graphite particle, or partially attached to the particle. The graphite platelets have an average thickness in the range of 1-100 nm. The graphite nanostructures are created from synthetic or natural graphite using a high-pressure mill. Fluid jets of the high-pressure flaking mill cause fluid to enter the tip of cracks in the graphite particles, which creates tension at the tip. This tension causes the cracks to propagate along the natural planes in the graphite so that small particles of the graphite separate into platelets. The platelets can be treated after the milling process by drying the platelets in a spray dryer. The platelets may optionally be introduced into a hydrocyclone to separate the platelets by size. The resulting graphite nanostructures can be added to conventional polymers to create polymer composites having increased mechanical characteristics, including an increased flexural modulus, heat deflection temperature, tensile strength, electrical conductivity, and notched impact strength.

What is claimed is:  
     
         1 . Graphite nanostructures in the form of platelets, wherein a majority of said platelets have an aspect ratio of at least 1,500:1.  
     
     
         2 . The graphite nanostructures of  claim 1 , wherein a majority of said platelets have a footprint of about 10 μm×30 μm.  
     
     
         3 . The graphite nanostructures of  claim 1 , wherein a majority of said platelets have a specific surface area of at least 5 m 2 /g.  
     
     
         4 . The graphite nanostructures of  claim 1 , wherein a majority of said platelets have an average thickness of less than 100 nm.  
     
     
         5 . Graphite nanostructures comprising a plurality of randomly-aligned platelets.  
     
     
         6 . Graphite platelets, wherein a majority of the platelets have a specific surface area of at least about 5 m 2 /g and an average thickness of less than 100 nm.  
     
     
         7 . The graphite platelets of  claim 6 , wherein said platelets are structurally independent and have a planar morphology and are of a geometrically angled shape.  
     
     
         8 . The graphite platelets of  claim 6 , wherein the average thickness is less than 50 nm.  
     
     
         9 . The graphite platelets of  claim 6 , wherein the average thickness is less than 20 nm.  
     
     
         10 . The graphite platelets of  claim 6 , wherein the platelets have an average aspect ratio of at least 1,500:1.  
     
     
         11 . The graphite platelets of  claim 6 , wherein the platelets have an average aspect ratio in the range of 1,500:1 to 20,000:1.  
     
     
         12 . The graphite platelets of  claim 6 , wherein the platelets have an average aspect ratio in the range of 1,500:1 to 8,000:1.  
     
     
         13 . The graphite platelets of  claim 6 , wherein a majority of the platelets have an angular periphery.  
     
     
         14 . Graphite platelets, wherein a majority of the platelets have an aspect ratio of at least 1,500:1, and an individual, average flake thickness of less than 100 nm.  
     
     
         15 . The graphite platelets of  claim 14 , wherein a majority of the platelets are structurally independent and have a planar morphology.  
     
     
         16 . The graphite platelets of  claim 14 , wherein a majority of the platelets have an angular periphery.  
     
     
         17 . The graphite platelets of  claim 14 , wherein the average thickness is less than 50 nm.  
     
     
         18 . The graphite platelets of  claim 14 , wherein the average thickness is less than 20 nm.  
     
     
         19 . The graphite platelets of  claim 14 , wherein the average aspect ratio is in the range of 1,500:1 to 100,000.  
     
     
         20 . The graphite platelets of  claim 14 , wherein the average aspect ratio is in the range of 1,500:1 to 20,000:1.  
     
     
         21 . The graphite platelets of  claim 14 , wherein the average aspect ratio is in the range of 1,500 to 8,000:1.  
     
     
         22 . A method for fracturing graphite particles into platelets, comprising: 
 introducing the graphite into a high-pressure flaking mill, wherein said high-pressure flaking mill causes a hydro-wedging effect that overcomes the Van der Waal forces of the particles and fractures said particles into platelets.    
     
     
         23 . The method of  claim 22 , wherein a majority of the platelets have an aspect ratio of at least 1,500:1.  
     
     
         24 . A polymer matrix composite, comprising: 
 a polymer; and    graphite platelets having a specific surface area of at least about 5 m 2 /g and an individual, average platelet thickness of less than 100 nm.    
     
     
         25 . The polymer matrix composite of  claim 24 , wherein said polymer is selected from the group consisting of: nylons, polyethylenes, polypropylenes, polystyrenes, polycarbonates, epoxies, polyimides, polyamides, fluorinated polymers, acryloides, polyacrylics, polyesters, cyanate esters and bismal imides.