High strength and high modulus carbon fibers

Abstract

Carbon fibers have been processed from gel spun polyacrylonitrile copolymer on a continuous carbonization line at Georgia Tech (GT) with a tensile strength in the range of 5.5–5.8GPa, and tensile modulus in the range of 354–375GPa. This combination of strength and modulus is the highest for any continuous fiber reported to date, and the gel spinning route provides a pathway for further improvements in strength and modulus for mass production of carbon fibers. At short gauge length, fiber tensile strength was as high as 12.1GPa, which is the highest value ever reported for a PAN based carbon fiber. Structure analysis shows random flaws of about 2nm size, which results in limiting tensile strength of higher than 20GPa. Inter-planar turbostratic graphite shear modulus in high strength carbon fibers is 30GPa, while in graphite the corresponding value is only 4GPa.