Hybrid fiber tows containning both nano-fillers and continuous fibers, hybrid composites, and their production processes

Abstract

Disclosed is a hybrid fiber tow that comprises multiple continuous filaments and nanoscale fillers embedded in the interstitial spaces between continuous filaments. Nanoscale fillers may be selected from a nanoscale graphene plate, non-graphite platelet, carbon nano-tube, nano-rod, carbon nano-fiber, non-carbon nano-fiber, or a combination thereof. Also disclosed are a hybrid fiber tow impregnated with a matrix material and a composite structure fabricated from a hybrid fiber tow. The composite exhibits improved physical properties (e.g., thermal conductivity) in a direction transverse to the continuous fiber axis. A roll-to-roll process for producing a continuous fiber tow or matrix-impregnated fiber tow and an automated process for producing composite structures containing both continuous filaments and nanoscale fillers are also provided.

1 . A hybrid fiber tow comprising multiple continuous filaments and nanoscale fillers embedded in interstitial spaces between said continuous filaments, wherein said nanoscale fillers comprise a nanoscale graphene plate, non-graphite platelet, carbon nano-tube, nano-rod, carbon nano-fiber, non-carbon nano-fiber, or a combination thereof. 
   
   
       2 . The hybrid fiber tow as defined in  claim 1 , wherein said nano-fillers comprise a nanoscale graphene plate or a non-graphite platelet with a width or length smaller than 10 μm. 
   
   
       3 . The hybrid fiber tow as defined in  claim 1 , wherein said nano-fillers comprise a nanoscale graphene plate or non-graphite platelet that has a length or width smaller than 500 nm. 
   
   
       4 . The hybrid fiber tow as defined in  claim 1 , further comprising a matrix-forming material embedded in interstitial spaces or coated on a surface of said continuous filaments. 
   
   
       5 . The hybrid fiber tow as defined in  claim 4 , wherein said matrix-forming material comprises a thermoplastic, a thermoset, or a combination thereof. 
   
   
       6 . The hybrid fiber tow as defined in  claim 1 , wherein said continuous filaments comprise a polymer fiber, ceramic fiber, carbon fiber, graphite fiber, glass fiber, or a combination thereof 
   
   
       7 . The hybrid fiber tow as defined in  claim 1 , wherein said nano-fillers are preferentially oriented in a direction substantially non-parallel to a continuous filament axial direction. 
   
   
       8 . A hybrid composite structure comprising a hybrid fiber tow as defined in  claim 1  and a matrix material. 
   
   
       9 . The hybrid composite as defined in  claim 8 , wherein said matrix material comprises a polymer, glass, carbon, ceramic, metal, or a combination thereof; said continuous filaments comprise a polymer fiber, ceramic fiber, carbon fiber, graphite fiber, glass fiber, or a combination thereof; and said nano-fillers comprise a nanoscale graphene plate, carbon nano-tube, carbon nano-fiber, or a combination thereof. 
   
   
       10 . A process for producing the hybrid fiber tow of  claim 1 , said process comprising
 a) spreading a continuous fiber tow into multiple, separated filaments that define interstitial spaces between said filaments;   b) exposing said separated filaments to a fluid medium or fluidized medium containing said nanoscale fillers suspended therein under a flow condition for a duration of time sufficient to cause said nanoscale fillers to be trapped and stay in said interstitial spaces; and   c) moving said separated filaments with said trapped interstitial nanoscale fillers away from said medium to produce said hybrid fiber tow.   
   
   
       11 . The process of  claim 10 , wherein said step of exposing comprises moving said separated filaments through a fluidized bed comprising a fluidized medium that contains said nanoscale particles suspended in said medium. 
   
   
       12 . The process of  claim 11 , wherein said fluidized bed is provisioned with electrostatic charging means to facilitate attraction of said nanoscale fillers to said filaments. 
   
   
       13 . The process of  claim 10 , wherein said step of exposing comprises moving said separated filaments through a fluid medium that contains said nanoscale particles suspended in a liquid or solution. 
   
   
       14 . The process of  claim 10 , wherein said step of exposing comprises moving said separated filaments at a desired speed in a desired direction while directing a stream of a liquid medium containing said nanoscale fillers to impinge upon said filaments in such a manner that said fillers are trapped in said interstitial spaces to form said hybrid fiber tow. 
   
   
       15 . The process of  claim 10 , wherein said step of exposing comprises moving said separated filaments at a desired speed in a desired direction while directing a stream of a gaseous medium carrying said nanoscale fillers to impinge upon said filaments in such a manner that said fillers are trapped in said interstitial spaces to form said hybrid fiber tow. 
   
   
       16 . The process of  claim 10  wherein said fluid medium or fluidized medium further contains a matrix-forming material and said step of exposing comprises causing both said nanoscale fillers and said matrix-forming material to stay in said interstitial spaces to form a matrix-forming material-impregnated hybrid tow, herein referred to as a hybrid fiber towpreg. 
   
   
       17 . The process of  claim 10 , further comprising a step of reeling said continuous fiber tow from a roller or spool prior to the fiber tow spreading step and a step of winding said hybrid fiber tow on a roller or drum. 
   
   
       18 . The process of  claim 16 , further comprising a step of reeling said continuous fiber tow from a roller or spool prior to the fiber tow spreading step and a step of winding said hybrid fiber towpreg on a roller or drum. 
   
   
       19 . The process of  claim 10 , further comprising
 d) reeling said continuous fiber tow from a roller or spool prior to the fiber tow spreading step;   e) impregnating said hybrid fiber tow obtained in step (c) with a matrix material to form a matrix-impregnated hybrid fiber tow;   f) subjecting said matrix-impregnated hybrid tow to a shape-forming operation to form a composite shape; and   g) consolidating said composite shape through heating, curing, and/or cooling said matrix material to form a hybrid composite structure.   
   
   
       20 . The process of  claim 19  wherein said shape-forming operation comprises a filament winding, fiber placement, prepreg-forming, pultrusion, freeform fabrication step, or a combination thereof. 
   
   
       21 . The process of  claim 10 , further comprising
 d) reeling said continuous fiber tow from a roller or spool prior to the fiber tow spreading step;   e) subjecting said hybrid fiber tow obtained in step (c) to a shape-forming operation to form a composite preform;   f) impregnating said preform with a matrix material; and   g) consolidating the matrix-impregnated preform through heating, curing, and/or cooling said matrix material to form a hybrid composite structure.   
   
   
       22 . The process of  claim 21  wherein said shape-forming operation comprises a step of filament winding, fiber placement, freeform fabrication, weaving, braiding, stitching, knitting, or a combination thereof. 
   
   
       23 . The process of  claim 16 , further comprising
 d) reeling said continuous fiber tow from a roller or spool prior to the fiber tow spreading step;   e) subjecting said hybrid fiber towpreg to a shape-forming operation to form a composite shape; and   g) consolidating said composite shape through heating, curing, and/or cooling said matrix-forming material to form a hybrid composite structure.   
   
   
       24 . The process of  claim 23  wherein said shape-forming operation comprises a step of filament winding, fiber placement, prepreg-forming, freeform fabrication, weaving, braiding, stitching, knitting, or a combination thereof. 
   
   
       25 . The process of  claim 19  wherein said step of consolidating comprises melting a matrix material, cooling or solidifying a matrix material, curing a resin, polymerizing or cross-linking a resin precursor, converting an organic or polymeric material to a carbonaceous material, or a combination thereof. 
   
   
       26 . The process of  claim 21  wherein said step of consolidating comprises melting a matrix material, cooling or solidifying a matrix material, curing a resin, polymerizing or cross-linking a resin precursor, converting an organic or polymeric material to a carbonaceous material, or a combination thereof. 
   
   
       27 . The process of  claim 23  wherein said step of consolidating comprises melting a matrix material, cooling or solidifying a matrix material, curing a resin, polymerizing or cross-linking a resin precursor, converting an organic or polymeric material to a carbonaceous material, or a combination thereof. 
   
   
       28 . The hybrid composite of  claim 8  wherein said nano-fillers are present at a loading of greater than 5% by weight based on the total weight of nano-fillers plus the matrix material. 
   
   
       30 . The hybrid composite of  claim 8  wherein said nano-fillers are present at a loading of at least 15% by weight based on the total weight of nano-fillers plus the matrix material. 
   
   
       30 . The hybrid composite of  claim 8  wherein said nano-fillers have an elongate axis that is inclined at an angle of at least 45 degrees with respect to a longitudinal axis of said continuous fibers.