Nanotube/matrix composites and methods of production and use

Abstract

A nanotube/matrix composite mixture, and a method of producing it, which can be used to form a composite material such as a drawn fiber having an increased strength over a drawn fiber formed from the matrix material alone. Nanotubes are combined with a solvent material to form a nanotube/solvent mixture. The nanotube/solvent mixture is mixed, for example by sonication, such that the nanotubes are uniformly dispersed in the nanotube/solvent mixture. An amount of a matrix material (with or without a solvent) is then combined with the nanotube/solvent mixture to form a nanotube/solvent/matrix mixture. The matrix material is polyethylene. The nanotube/solvent mixture and the matrix material are mixed such that the nanotubes are maintained in uniformly dispersed state in the nanotube/solvent/matrix mixture, for example by continued sonication after the nanotubes and matrix material are combined. The solvent material is then substantially removed from the nanotube/solvent/matrix mixture to form the nanotube/matrix composite mixture, which can then be used in a commercial process to produce a composite material such as drawn fiber, as produced, for example, by melt spinning.

1 . A method for forming a nanotube/matrix composite mixture, comprising the steps of: 
 a. combining an amount of single walled carbon nanotubes with a solvent material to form a nanotube/solvent mixture and mixing the nanotube/solvent mixture for a predetermined mixing period such that the single walled carbon nanotubes are uniformly dispersed in the nanotube/solvent mixture;    b. combining an amount of a matrix material with the single walled nanotube/solvent mixture having the single walled carbon nanotubes uniformly dispersed therein to form a nanotube/solvent/matrix mixture and mixing the nanotube/solvent/matrix mixture for a predetermined mixing period such that the single walled carbon nanotubes are uniformly dispersed in the nanotube/solvent/matrix mixture, the matrix material being polyethylene; and    c. removing a substantial amount of the solvent material from the nanotube/solvent/matrix mixture to form a nanotube/matrix composite mixture comprising less than about 5% by weight of the solvent material.    
     
     
         2 . The method of  claim 1 , wherein the solvent is decalin, toluene, or a combination thereof.  
     
     
         3 . The method of  claim 1 , wherein in step (a) the nanotube solvent mixture further comprises a surfactant.  
     
     
         4 . The method of  claim 1 , further comprising the steps of: 
 d. heating the nanotube/matrix composite mixture to a temperature above the melting point of the matrix material; and    e. passing the heated nanotube/matrix composite mixture through an orifice to form an extrudate.    
     
     
         5 . The method of  claim 4 , further comprising the step of: 
 f. drawing the extrudate to form a drawn fiber.    
     
     
         6 . The method of  claim 5 , wherein step (f) is further defined as the steps of passing the extrudate through an oven and simultaneously stretching the extrudate wherein the drawn fiber has a diameter less than a diameter of the extrudate.  
     
     
         7 . The nanotube/matrix composite mixture produced by the method of  claim 1 .  
     
     
         8 . The extrudate produced by the method of  claim 4 .  
     
     
         9 . A composite material produced from the nanotube/matrix composite mixture of  claim 7 .  
     
     
         10 . The drawn fiber produced by the method of  claim 5 .  
     
     
         11 . The drawn fiber of  claim 10  having a stress-strain behavior at least 50% greater than a stress-strain behavior of a drawn fiber produced from the matrix material without nanotubes.  
     
     
         12 . The drawn fiber produced by the method of  claim 6 .  
     
     
         13 . The drawn fiber of  claim 12  having a stress-strain behavior at least 50% greater than a stress-strain behavior of a drawn fiber produced from the matrix material without nanotubes.  
     
     
         14 . The method of  claim 1  wherein the nanotube/matrix composite mixture formed in step (c) comprises from about 0.5% to 1.5% by weight of single walled carbon nanotubes after step (d).  
     
     
         15 . The method of  claim 1  wherein in step (a) the solvent material comprises more that one solvent.  
     
     
         16 . The method of  claim 1  wherein the predetermined mixing period of step (a) is a length of time such that the single walled carbon nanotubes remain substantially unbroken before step (b).  
     
     
         17 . The method of  claim 16  wherein the predetermined mixing period of step (b) is a length of time such that the single walled carbon nanotubes remain substantially unbroken before step (c).  
     
     
         18 . A method for forming a nanotube/matrix composite mixture, comprising the steps of: 
 a. combining an amount of single walled carbon nanotubes with a first solvent material to form a nanotube/solvent mixture and mixing the nanotube/solvent mixture for a predetermined mixing period such that the single walled carbon nanotubes are uniformly dispersed in the nanotube/solvent mixture;    b. combining an amount of a matrix material with a second solvent material to form a matrix/solvent mixture and mixing the matrix material and the second solvent material in the matrix/solvent mixture, the second solvent material being miscible with the first solvent material, the matrix material being polyethylene;    c. combining the nanotube/solvent mixture with the matrix/solvent mixture to form a nanotube/solvent/matrix mixture and mixing the nanotube/solvent/matrix mixture for a predetermined mixing period such that the single walled carbon nanotubes therein are uniformly dispersed in the nanotube/solvent/matrix mixture; and    d. removing the first and second solvent materials from the nanotube/solvent/matrix mixture to form a nanotube/matrix composite mixture comprising less than about 5% by weight of the first and second solvent materials.    
     
     
         19 . The method of  claim 18 , wherein the first solvent material and the second solvent material are selected from the group consisting of decalin, toluene, and combinations thereof.  
     
     
         20 . The method of  claim 18 , wherein step (a) further comprises combining a surfactant material with the nanotube/solvent mixture and/or step (b) further comprises combining a surfactant with the matrix/solvent mixture.  
     
     
         21 . The method of  claim 18 , further comprising the steps of: 
 e. heating the nanotube/matrix composite mixture to a temperature above the melting point of the matrix material; and    f. passing the heated nanotube/matrix composite mixture through an orifice to form an extrudate.    
     
     
         22 . The method of  claim 18 , further comprising the steps of: 
 g. drawing the extrudate to form a drawn fiber.    
     
     
         23 . The method of  claim 22 , wherein step (g) is further defined as the steps of passing the extrudate through an oven and simultaneously stretching the extrudate wherein the drawn fiber has a diameter less than a diameter of the extrudate.  
     
     
         24 . The nanotube/matrix composite mixture produced by the method of  claim 18 .  
     
     
         25 . A composite material produced from the nanotube/matrix composite mixture of  claim 24 .  
     
     
         26 . The extrudate produced by the method of  claim 21 .  
     
     
         27 . The drawn fiber produced by the method of  claim 22 .  
     
     
         28 . The drawn fiber of  claim 27  having a stress-strain behavior at least 50% greater than a stress-strain behavior of a drawn fiber produced from the matrix material without nanotubes.  
     
     
         29 . The drawn fiber produced by the method of  claim 23 .  
     
     
         30 . The drawn fiber of  claim 29  having a stress-strain behavior at least 50% greater than a stress-strain behavior of a drawn fiber produced from the matrix material without nanotubes.  
     
     
         31 . The method of  claim 18  wherein the nanotube/matrix composite mixture formed in step (d) comprises from about 0.5% to 1.5% by weight of single walled carbon nanotubes.  
     
     
         32 . The method of  claim 18  wherein in step a the solvent material comprises more that one solvent.  
     
     
         33 . The method of  claim 18  wherein the predetermined mixing period of step (a) is a length of time such that the single walled carbon nanotubes remain substantially unbroken before step (b).  
     
     
         34 . The method of  claim 33  wherein the predetermined mixing period of step (b) is a length of time such that the single walled carbon nanotubes remain substantially unbroken before step (c).