Method of making polyacrylonitrile based carbon fibers and polyacrylonitrile based carbon fiber fabric

Abstract

Methods to produce a polyacrylonitrile-based carbon fiber and polyacrylonitrile-based carbon fiber fabric with physical characteristic closely resembling rayon-based carbon fibers are disclosed. A polyacrylonitrile-based carbon fiber and polyacrylonitrile-based carbon fiber fabric with a unique combination of physical properties are also disclosed.

What is claimed: 
     
         1 . A method of producing polyacrylonitrile (PAN)-based carbon fibers, comprising:
 extruding a PAN dope through a spinneret to produce a tow of PAN fibers having a lobed cross section and a glass transition temperature above 100° C.;   washing, drying and winding the tow of PAN fibers without subjecting the PAN fibers to hot drawing at a temperature at or above 100° C.; and   stabilizing and carbonizing the tow of PAN fibers at a temperature of less than 1,000° C. to produce PAN-based carbon fibers.   
     
     
         2 . The method of  claim 1 , including using a spinneret with a +-shaped opening to produce PAN fiber filaments having a cross section with a lobed shape. 
     
     
         3 . The method of  claim 2 , wherein the stabilizing includes heating the tow of PAN fibers to 240°−280° C. 
     
     
         4 . The method of  claim 2 , wherein a highest fiber temperature reached during carbonization is between 850° C. and 950° C. 
     
     
         5 . The method of  claim 2 , wherein a highest fiber temperature reached during carbonization is between 885° C. and 915° C. 
     
     
         6 . A method of producing a polyacrylonitrile (PAN)-based carbon fiber fabric, comprising:
 extruding a PAN dope through a spinneret to produce a tow of PAN fibers having a lobed cross section and a glass transition temperature above 100° C.;   washing, drying and winding the tow of PAN fibers without subjecting the PAN fibers to hot drawing at a temperature at or above 100° C.;   weaving the tow of PAN fibers into a woven PAN fiber fabric; and   stabilizing and carbonizing the woven PAN fiber fabric at a temperature of less than 1,000° C. to produce PAN-based woven carbon fiber fabric.   
     
     
         7 . The method of  claim 6 , including using a spinneret with a +-shaped opening to produce PAN fiber filaments having a cross section with a lobed shape. 
     
     
         8 . The method of  claim 7 , wherein the stabilizing includes heating the woven PAN fiber fabric to 265° C. 
     
     
         9 . The method of  claim 6 , wherein a highest fiber temperature reached during carbonization is between 850° C. and 950° C. 
     
     
         10 . The method of  claim 6 , wherein a highest fiber temperature reached during carbonization is between 885° C. and 915° C. 
     
     
         11 . The method of  claim 6 , including using a spinneret with a +-shaped opening to produce PAN fibers having a cross section with a lobed shape. 
     
     
         12 . The PAN-based carbon fibers made by the method of  claim 1 . 
     
     
         13 . The PAN-based carbon fibers of  claim 12 , wherein lobes of PAN fiber filaments have a characteristic width greater than 10% of a width of said PAN fiber filaments at a largest dimension of said PAN fiber filaments. 
     
     
         14 . The PAN-based carbon fiber fabric made by the method of  claim 7 . 
     
     
         15 . The PAN-based carbon fiber fabric of  claim 14 , wherein lobes of said PAN fiber filaments have a characteristic width greater than 10% of a width of said PAN fiber filaments at a largest dimension of said fiber. 
     
     
         16 . A PAN-based carbon fiber, comprising a thermal diffusivity of less than 2 mm 2 /sec along a longitudinal axis of the PAN-based carbon fiber, a modulus of less than 100 GPa along the longitudinal axis in tension, and a lobe width W 1 /max fiber diameter W f  greater than 0.1. 
     
     
         17 . The PAN-based carbon fiber of  claim 16 , wherein the thermal diffusivity is less than 1.6 mm 2 /sec along the longitudinal axis of the PAN-based carbon fiber. 
     
     
         18 . The PAN-based carbon fiber of  claim 17 , wherein the modulus is less than 65 GPa along the longitudinal axis in tension. 
     
     
         19 . The PAN-based carbon fiber of  claim 16 , wherein the PAN-based carbon fiber has a break stress of less than 1 GPa along the longitudinal axis in tension.