Composite carbon fibers

Abstract

A composite carbon fiber having a carbon fiber to which an amine-functionalized polymer is electro-grafted onto a surface thereof is provided. Electro-grafting the amine-functionalized polymer onto the surface of the carbon fiber results in a composite carbon fiber in which the polymer is covalently bonded to the fiber, and in which a significant number of reactive amine groups are available for subsequent reactions, such as for reacting with a resin matrix in the production of a fiber reinforced composite. As a result, the composite carbon fibers may be particularly useful in producing fibers reinforced composites that exhibit improved interlaminar strength. Fiber reinforced composites are also provided.

1 .- 56 . (canceled) 
     
     
         57 . A composite carbon fiber comprising a carbon fiber having an amine-functionalized polymer electro-grafted onto a surface thereof. 
     
     
         58 . The composite carbon fiber of  claim 57 , wherein the composite carbon fiber has a nitrogen/carbon (N/C) ratio that is at least 0.125. 
     
     
         59 . The composite carbon fiber of  claim 57 , wherein the composite carbon fiber has a N/C ratio that is from about 0.15 to 0.3. 
     
     
         60 . The composite carbon fiber of  claim 57 , wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is at least 50% in comparison to the original carbon fiber that does not include an amine-functionalized polymer electro-grafted onto the surface of the carbon fiber. 
     
     
         61 . The composite carbon fiber of  claim 57 , wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is from about 50 to 500% in comparison to the original carbon fiber that does not include an amine-functionalized polymer electro-grafted onto the surface of the carbon fiber. 
     
     
         62 . The composite carbon fiber of  claim 57 , wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is from about 150 to 500% in comparison to the original carbon fiber that does not include an amine-functionalized polymer electro-grafted onto the surface of the carbon fiber. 
     
     
         63 . The composite carbon fiber of  claim 57 , wherein the amine-functionalized polymer is selected from the group consisting of linear polyethyleneimines (PEI), branched polyethyleneimines (PEI), branched polypropyleneimine, linear poly(allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, branched poly(allylamine) prepared by branching of poly(allylamine) with divinylbenzene (PAADVB), and block-copolymers, core-shell particles, and combinations thereof. 
     
     
         64 . The composite carbon fiber of  claim 57 , wherein the amine-functionalized polymer comprises a branched polyethyleneimine. 
     
     
         65 . The composite carbon fiber of  claim 57 , wherein the carbon fiber has a tensile strength of at least 400 ksi. 
     
     
         66 . The composite carbon fiber of  claim 57 , wherein the carbon fiber has a tensile strength from about 600 to 1,050 ksi. 
     
     
         67 . The composite carbon fiber of  claim 57 , wherein the amine-functionalized polymer has a weight average molecular weight ranging from about 5,000 to 35,000. 
     
     
         68 . A fiber reinforced composite comprising the composite carbon fiber of  claim 57 . 
     
     
         69 . A composite carbon fiber comprising a carbon fiber having an amine-functionalized polymer electro-grafted onto a surface thereof, and wherein the composite carbon fiber is characterized by:
 a) a nitrogen/carbon (N/C) ratio that is at least 0.125; and   b) an increase in nitrogen surface concentration that is from about 50 to 3,000% in comparison to the original carbon fiber that does not include an amine-functionalized polymer electro-grafted onto the surface of the carbon fiber.   
     
     
         70 . The composite carbon fiber of  claim 69 , wherein the composite carbon fiber exhibits a nitrogen/carbon (N/C) ratio that is from about 0.15 to 0.3, and an increase in surface of nitrogen concentration of any one or more of at least 75%, at least 100%, at least 125%, at least 150%, at least 175%, at least 200%, at least 225%, at least 250%, at least 275%, at least 300%, at least 325%, at least 350%, at least 375%, at least 400%, at least 425%, at least 450%, at least 475%, or at least 500%, in comparison to the original carbon fiber that has not had an amine-functionalized polymer electro-grafted onto its surface. 
     
     
         71 . The composite carbon fiber of  claim 69 , wherein the composite carbon fiber exhibits an increase in surface of nitrogen concentration ranging from about 100 to 500% in comparison to the original carbon fiber that has not had an amine-functionalized polymer electro-grafted onto its surface. 
     
     
         72 . The composite carbon fiber of  claim 69 , wherein the amine-functionalized polymer is selected from the group consisting of linear polyethyleneimines (PEI), branched polyethyleneimines (PEI), branched polypropyleneimine, linear poly(allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, branched poly(allylamine) prepared by branching of poly(allylamine) with divinylbenzene (PAADVB), and a combination thereof. 
     
     
         73 . The composite carbon fiber of  claim 69 , wherein the carbon fiber has a tensile strength from about 600 to 1,050 ksi, and the amine-functionalized polymer has a weight average molecular weight ranging from about 5,000 to 35,000. 
     
     
         74 . A fiber reinforced composite comprising a carbon fiber having an amine-functionalized polymer electro-grafted onto a surface thereof, and a resin matrix infused into the carbon fiber, wherein the fiber reinforced composite exhibits an interlaminar strength of about 17 to 25 ksi as characterized by Short Beam Shear (SBS) testing. 
     
     
         75 . The fiber reinforced composite of  claim 74 , wherein the interlaminar strength of the fiber reinforced composite is about 20 to 22 ksi as characterized by SBS. 
     
     
         76 . The fiber reinforced composite  claim 74 , wherein the fiber reinforced composite exhibits an increase in SBS ranging from about 5 to 25% in comparison to a similar fiber reinforced composite in which the carbon fibers are identical with the exception that the surfaces of the carbon fibers do not include an amine-functionalized polymer. 
     
     
         77 . The fiber reinforced composite  claim 74 , wherein a surface of the composite carbon fiber has a nitrogen/carbon (N/C) ratio that is from about 0.15 to 0.3. 
     
     
         78 . The fiber reinforced composite of  claim 77 , wherein the composite carbon fiber exhibits an increase in surface of nitrogen concentration of any one or more of least 25%, at least 50%, at least 75%, at least 100%, at least 125%, at least 150%, at least 175%, at least 200%, at least 225%, at least 250%, at least 275%, at least 300%, at least 325%, at least 350%, at least 375%, at least 400%, at least 425%, at least 450%, at least 475%, or at least 500%, in comparison to the original carbon fiber that has not had an amine-functionalized polymer electro-grafted onto its surface. 
     
     
         79 . The fiber reinforced composite of  claim 77 , wherein the composite carbon fiber exhibits an increase in surface of nitrogen concentration ranging from about 100 to 500%, in comparison to the original carbon fiber that has not had an amine-functionalized polymer electro-grafted onto its surface. 
     
     
         80 . The fiber reinforced composite of  claim 74 , wherein the resin is selected from the group consisting of epoxy based resins, bismaleimide based resins, cyanate ester based resins, and phenolic based resins. 
     
     
         81 . The fiber reinforced composite of  claim 74 , wherein the carbon fiber has a tensile strength from about 600 to 1,050 ksi. 
     
     
         82 . The fiber reinforced composite of  claim 74 , wherein the amine-functionalized polymer is selected from the group consisting of linear polyethyleneimines (PEI), branched polyethyleneimines (PEI), branched polypropyleneimine, linear poly(allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, branched poly(allylamine) prepared by branching of poly(allylamine) with divinylbenzene (PAADVB), and a combination thereof. 
     
     
         83 . An aerospace part comprising the fiber reinforced composite of  claim 74 . 
     
     
         84 . A method of preparing a composite carbon fiber comprising
 passing a carbon fiber through a bath comprising an amine-functionalized polymer;   applying an electro-potential to the cell;   electro-grafting the amine-functionalized polymer onto the carbon fiber to produce a composite carbon fiber having an amine-functionalized polymer electro-grafted onto a surface thereof, and wherein the composite carbon fiber is characterized by:   a) a carbon/nitrogen (N/C) ratio that is at least 0.125; and/or   b) an increase in nitrogen surface concentration that is from about 50 to 500% in comparison to the original carbon fiber that does not include an amine-functionalized polymer electro-grafted onto the surface of the carbon fiber.   
     
     
         85 . The method of  claim 84 , wherein the composite carbon fiber exhibits a nitrogen/carbon (N/C) ratio that is from about 0.15 to 0.3, and wherein the composite carbon fiber exhibits an increase in surface of nitrogen concentration of any one or more at least 100%, in comparison to the original carbon fiber that has not had an amine-functionalized polymer electro-grafted onto its surface. 
     
     
         86 . The method of  claim 84 , wherein the step of electro-grafting the amine-functionalized polymer onto the carbon fiber lasts for a period of time between 30 seconds and two minutes. 
     
     
         87 . The method of  claim 84 , wherein the step of electro-grafting the amine-functionalized polymer onto the carbon fiber lasts for a period of time between 45 seconds and 90 seconds.