Expanded graphite and products produced therefrom

Abstract

Graphite nanoplatelets of expanded graphite and composites and products produced therefrom are described. The preferred method of expanding the graphite is by microwaves or other radiofrequency wave treatment of intercalated graphite. The expanded graphite is preferably then crushed to nanometer (substantially all 200 microns or less). The expanded graphite is used in polymer composites. The expanded graphite is particularly useful for batteries, anodes and fuel cells.

1 . A composite material which comprises: 
 (a) expanded graphite wherein a precursor graphite containing a chemical has been expanded by heating with microwaves or radiofrequency waves to produce the expanded graphite and to at least in part vaporize the chemical; and    (b) a polymer having the expanded graphite dispersed therein.    
     
     
         2 . A composite material which comprises: 
 (a) expanded graphite wherein a precursor graphite containing a chemical has been expanded by heating with microwaves or radiofrequency waves to produce the expanded graphite and to at least in part vaporize the chemical; and    (b) a polymer having the expanded graphite particles dispersed therein, wherein the composite material contains up to about 50% by volume of the graphite.    
     
     
         3 . The composite material of  claim 2  wherein the graphite is present in an amount so that composite material is conductive.  
     
     
         4 . The composite material of any one of claims  1 ,  2  or  3  wherein the polymer is a thermoplastic or thermoset polymer.  
     
     
         5 . (canceled)  
     
     
         6 . The composite material of any one of claims  1 ,  2  or  3  wherein the expanded graphite has been formed in a radiofrequency wave applicator by heating a graphite precursor with the radiofrequency waves or microwaves.  
     
     
         7 . The composite material of any one of claims  1 ,  2  or  3  wherein the polymer and the expanded graphite have been heated together with the radiofrequency waves or microwaves.  
     
     
         8 . The composite material of any one of claims  1 ,  2 , or  3  wherein the polymer is an epoxy resin.  
     
     
         9 . The composite material of any one of claims  1 ,  2  or  3  wherein the precursor graphite has been treated with a fuming oxy acid and heated to form the expanded graphite.  
     
     
         10 . The composite material of any one of claims  1 ,  2  or  3  wherein the polymer is thermoplastic and is selected from the group consisting of polyamides, proteins, polyesters, polyethers, polyurethanes, polysiloxanes, phenol-formaldehydes, urea-formaldehydes, melamine-formaldehydes, celluloses, polysulfides, polyacetals, polyethylene oxides, polycaprolactams, polycaprolactons, polylactides, polyimides, and polyolefins.  
     
     
         11 . The composite material of any one of claims  1 ,  2  or  3  which contains less than about 8% by weight of the expanded graphite.  
     
     
         12 . A method for preparing a shaped composite which comprises: 
 (a) providing a mixture of an expanded graphite wherein a precursor graphite containing a chemical has been expanded by heating with microwaves or radiofrequency waves to produce the expanded graphite and to at least in part vaporize the chemical and a polymer with the expanded graphite dispersed therein; and    (b) forming the shaped composite material from the mixture.    
     
     
         13 . A method for preparing a shaped composite material which comprises: 
 (a) providing a mixture of an expanded graphite wherein a precursor graphite containing a chemical has been expanded by heating with microwaves or radiofrequency waves to produce the expanded graphite and to vaporize the chemical and a polymer with the expanded graphite dispersed therein, wherein the composite material contains up to about 50% by volume of the expanded graphite platelets;    (b) forming the shaped composite material from the mixture.    
     
     
         14 . The method of claims  12  or  13  wherein the expanded graphite is provided in the polymer in an amount sufficient to render the shaped composite conductive.  
     
     
         15 . The method of claims  12  or  13  wherein the polymer is a thermoplastic or thermoset polymer.  
     
     
         16 . (canceled)  
     
     
         17 . The method of claims  12  or  13  wherein the expanded graphite is formed by heating the graphite precursor with the microwaves.  
     
     
         18 . The method of claims  12  or  13  wherein the graphite precursor is treated with a fuming oxy acid and heated to provide the expanded graphite.  
     
     
         19 . The method of any one of claims  12  or  13  wherein the polymer is a curable thermoset resin which is mixed with the expanded graphite and cured.  
     
     
         20 . The method of claims  12  or  13  wherein the shaped composite material contains less than 8% by weight of the expanded graphite.  
     
     
         21 . In a battery containing ions the improvement in the anode which comprises a finely divided microwave or RF expanded graphite wherein a precursor graphite containing a chemical has been expanded by heating with microwaves or radiofrequency waves to produce the expanded graphite and to vaporize the chemical.  
     
     
         22 . In a catalytic conversion of an organic compound to hydrogen with a catalytic material deposited on a substrate the improvement in the substrate which comprises a microwave or RF expanded graphite wherein a precursor graphite has been expanded by heating with microwaves or radiofrequency waves to produce the expanded graphite and to vaporize the chemical.  
     
     
         23 - 28 . (canceled)  
     
     
         29 . An expanded graphite which has been expanded by heating a graphite precursor containing a chemical with microwaves or radiofrequency waves to produce the expanded graphite and to vaporize the chemical.  
     
     
         30 . The graphite of  claim 29  as a pressed sheet.