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AssigneesToray Industries, Inc., Toray Research Center, Inc.
InventorsYoji Matsuhisa, Toru Hiramatsu, Kazuo Yoshida, Gen Katagiri
Estimating the term…
Disclosed is a carbon fiber made from an acrylic fiber, the carbon crystal of which has a crystal size Lc of 15 to 65 .ANG. as determined by the wide angle X-ray diffractometry. This carbon fiber has regions with a lower crystallinity in the surface layer portion thereof than that of the central portion thereof, and the compressive strength .sigma..sub.cf (GPa) of the single filament thereof determined by the loop method satisfies formula (I): .sigma..sub.cf .gtoreq.10.78-0.1176.times. Lc (I). The carbon fiber is produced by ionizing in vacuo an atom or molecule which is solid or gaseous at normal temperature, accelerating the ionized atom or molecule by an electric field, and implanting the accelerated ionized atom or molecule in a bundle of carbon fibers.
A carbon fiber made from an acrylic fiber, having improved compressive strength, having a crystal size L.sub.c of 15 to 65 angstroms as determined by wide angle X-ray diffractometry, and having regions which have a lower crystallinity in the surface layer portion thereof than in the central portion thereof and whose compressive strength (.sigma..sub.cf) of a single filament of said carbon fiber, determined by the loop method, satisfies the following formula (I):
A carbon fiber made from an acrylic fiber, having improved compressive strength, having a .nu.a/.nu.b ratio of at least 1.5 where .nu.a is a half width of the scattering peak at 1320 to 1380 cm.sup.-1 of the laser Raman spectrum of at least part of regions in a surface layer portion of a single filament of said carbon fiber and .nu.b is a half width of the scattering peak at 1320 to 1380 cm.sup.-1 of the laser Raman spectrum of the central portion of said single filament.
Dependencies are inferred from the claim text.