Abstract: A carbon fiber bundle that satisfies retaining a twist count of 2 turns/m or more when suspended with one end fixed and the other end free; having a single fiber diameter of 6.1 ?m or more and a heat loss rate at 450° C. of 0.15% or less, and formula (1) wherein Lc is crystallite size and ?002 is an orientation parameter of crystallites determined from bulk measurement of the entire fiber bundle: ?002>4.0×Lc+73.2 (1); and a carbon fiber bundle that satisfies: retaining a surface layer twist angle of 0.2° or more when suspended with one end fixed and the other end free; having a single fiber diameter of 6.1 ?m or more and a heat loss rate at 450° C. of 0.15% or less, and formula (1).

Abstract: A carbon fiber bundle has a relationship among a crystallite size Lc (nm), a single-fiber compressive strength Fc (GPa) measured by a compressive fragmentation method of single-fiber composites, and an initial modulus E0 (GPa) in a resin-impregnated strand tensile test simultaneously satisfies formulas (1) to (3), and Lc is 4.00 nm or less: Fc?1.3×10/Lc?0.3??(1) E0?80×Lc+155??(2) E0?330??(3).

Abstract: [Problem] To provide a sizing-agent-coated carbon fiber bundle in which, even when the sizing-agent-coated carbon fiber bundle has superior handling properties, the sizing agent on the sizing-agent-coated carbon fiber bundle exhibits excellent solubility in water and the adhesion amount of remaining sizing agent is reduced. [Solution] A sizing-agent-coated carbon fiber bundle obtained by applying polyethylene glycol and/or a surfactant to a carbon fiber bundle as a sizing agent, wherein all of the following conditions (i)-(iii) are satisfied. (i) The adhesion amount of the sizing agent is 0.15-0.80 parts by mass (inclusive) per 100 mass parts of the sizing-agent-coated carbon fiber bundle 100. (ii) The dry F-F friction coefficient is 0.39 or less. (iii) The adhesion amount of the sizing agent after washing for 50 seconds under the conditions disclosed in the specification is 0.12 parts by mass or less per 100 parts by mass of the sizing-agent-coated carbon fiber bundle 100.

Abstract: Provided is a resin composition including carbon fibers and a thermoplastic resin, in which the carbon fibers have a tensile elastic modulus E of 350 to 500 GPa, and the tensile elastic modulus E (GPa) and a loop fracture load A (N) satisfy the relationship of A??0.0017×E+1.02. This resin composition not only has a high moldability into a member of a complex shape by injection molding, but also can yield a molded article having excellent flexural modulus and excellent impact characteristics.

Abstract: A carbon fiber bundle is characterized in that a ratio (n/N) of a number n of pairs wherein a flaw of 50 nm in size or more is present on at least one of the fracture surfaces forming the pair to a total number N of pairs of fiber fracture surfaces selected at random after performing a single fiber tensile test for a gauge length of 10 mm is 35% or less, and in that a single-fiber diameter d is 4.3 ?m or more.

Abstract: A carbon fiber bundle includes single-fibers 40% or more of which have a quasi-oval cross section perpendicular to a fiber direction and meet both Equations (1) and (2): 1.03?La/Lb?1.20 (1) and 1.05?Ld/Lc?1.25 (2), wherein La is length of a long axis defined as a line segment connecting two points farthest away from each other on a circumference of the quasi-oval cross section of a single-fiber; Lb is length of a short axis defined as a line segment extending perpendicular to the long axis, passing through a midpoint of the long axis, and connecting two points on the circumference; and Lc and Ld are defined as length of a shorter one and that of a longer one, respectively.

Abstract: A carbon fiber having a strand elastic modulus of 360 GPa or more, a strand strength of 3.5 GPa or more, and a single-fiber diameter of 6.0 ?m or more, and having a residual twist count of 2 turns/m or more in a test in which one end is fixed end and another end is free end which is capable of rotation about the axis of a fiber bundle.

Abstract: A carbon fiber bundle has a relationship among a crystallite size Lc (nm), a single-fiber compressive strength Fc (GPa) measured by a compressive fragmentation method of single-fiber composites, and an initial modulus E0 (GPa) in a resin-impregnated strand tensile test simultaneously satisfies formulas (1) to (3), and Lc is 4.00 nm or less: Fc?1.3×10/Lc?0.3??(1) E0?80×Lc+155??(2) E0?330??(3).

Abstract: A carbon fiber includes single fibers having lengths of 10 cm or less, a fiber axis of each single fiber having an undulation width of 2.5 ?m or more when a part thereof between two points with a straight-line distance of 1 mm is observed from a lateral direction, and a coefficient of variation in the undulation width being 100% or less. A method of producing carbon fiber production includes performing stabilization treatment of a precursor fiber bundle for polyacrylonitrile based carbon fiber, performing pre-carbonization treatment, and performing carbonization treatment in this order, followed by cutting the resulting carbon fiber bundle in the form of continuous fiber to a single fiber length of 10 cm or less, the twist count of the fiber bundle during the carbonization treatment step being 16 turns/m or more.

Abstract: A carbon fiber bundle that satisfies retaining a twist count of 2 turns/m or more when suspended with one end fixed and the other end free; having a single fiber diameter of 6.1 ?m or more and a heat loss rate at 450° C. of 0.15% or less, and formula (1) wherein Lc is crystallite size and ?002 is an orientation parameter of crystallites determined from bulk measurement of the entire fiber bundle: ?002>4.0×Lc+73.2 (1); and a carbon fiber bundle that satisfies: retaining a surface layer twist angle of 0.2° or more when suspended with one end fixed and the other end free; having a single fiber diameter of 6.1 ?m or more and a heat loss rate at 450° C. of 0.15% or less, and formula (1).

Abstract: A carbon fiber bundle is obtained by filtering a spinning dope solution in which a polyacrylonitrile copolymer is dissolved in a solvent, at a predetermined filtration speed, using a filter medium having a predetermined particle retention and a filter basis weight, then spinning the filtered spinning dope solution to obtain a precursor fiber bundle for carbon fiber, and heat-treating the obtained precursor fiber bundle for carbon fiber at an appropriate temperature profile in an oxidizing atmosphere until reaching a predetermined density to obtain an oxidized fiber bundle, and then heat-treating the oxidized fiber bundle at a predetermined temperature in an inert atmosphere.

Abstract: A carbon fiber bundle is characterized in that a ratio (n/N) of a number n of pairs wherein a flaw of 50 nm in size or more is present on at least one of the fracture surfaces forming the pair to a total number N of pairs of fiber fracture surfaces selected at random after performing a single fiber tensile test for a gauge length of 10 mm is 35% or less, and in that a single-fiber diameter d is 4.3 ?m or more.

Abstract: A coagulated yarn, which is used to manufacture carbon fiber, is a coagulated yarn the surface hole diameter of which is 30 nm or less and the degree of swelling is less than 100% or a coagulated yarn the surface hole diameter of which is 30 nm or less and the inner hole diameter is 30 nm or less. The carbon fiber precursor fiber and the carbon fiber are obtained using such a coagulated yarn.

Abstract: A bundle of carbon fibers has a value A obtained from a nonlinear approximation formula of a stress ?-strain ? curve in a tensile strength test of resin-impregnated strands and an orientation parameter ? (%) of crystallites in a wide-angle x-ray diffraction measurement which satisfy a predetermined relational expression, and has tensile strength with a predetermined value or more, and tensile modulus within a predetermined range and a product E×d/W of a ratio d/W of a single-fiber diameter d to a loop width W just before loop fracture evaluated by a single-fiber loop test and a tensile modulus E of the strands has a predetermined value or more, or apparent single-fiber stress has a predetermined value or more when the number of fiber breaks by a single-fiber fragmentation method for a single-fiber composite is 0.30 breaks/mm and when the number of the fiber breaks by the single-fiber fragmentation method for the single-fiber composite is 0.

Abstract: A bundle of carbon fibers has a value A obtained from a nonlinear approximation formula of a stress ?-strain ? curve in a tensile strength test of resin-impregnated strands and an orientation parameter H (%) of crystallites in a wide-angle x-ray diffraction measurement which satisfy a predetermined relational expression, and has tensile strength with a predetermined value or more, and tensile modulus within a predetermined range and a product E×d/W of a ratio d/W of a single-fiber diameter d to a loop width W just before loop fracture evaluated by a single-fiber loop test and a tensile modulus E of the strands has a predetermined value or more, or apparent single-fiber stress has a predetermined value or more when the number of fiber breaks by a single-fiber fragmentation method for a single-fiber composite is 0.30 breaks/mm and when the number of the fiber breaks by the single-fiber fragmentation method for the single-fiber composite is 0.

Abstract: A sizing agent-coated carbon fiber bundle has a sizing agent containing an aliphatic epoxy compound (C) and an aromatic epoxy compound (D) coated on the carbon fiber bundle, wherein the carbon fiber in the carbon fiber bundle is the one which exhibits, when measured by single-fiber composite fragmentation method, a number of fiber breaks of at least 2.0/mm when apparent single-fiber stress is 15.3 GPa and the number of fiber breaks of up to 1.7/mm when the apparent single-fiber stress is 12.2 GPa.

Abstract: A carbon fiber bundle includes single-fibers 40% or more of which have a quasi-oval cross section perpendicular to a fiber direction and meet both Equations (1) and (2): 1.03?La/Lb?1.20 (1) and 1.05?Ld/Lc?1.25 (2), wherein La is length of a long axis defined as a line segment connecting two points farthest away from each other on a circumference of the quasi-oval cross section of a single-fiber; Lb is length of a short axis defined as a line segment extending perpendicular to the long axis, passing through a midpoint of the long axis, and connecting two points on the circumference; and Lc and Ld are defined as length of a shorter one and that of a longer one, respectively.

Abstract: A sizing agent-coated carbon fiber bundle has a sizing agent containing an aliphatic epoxy compound (C) and an aromatic epoxy compound (D) coated on the carbon fiber bundle, wherein the carbon fiber in the carbon fiber bundle is the one which exhibits, when measured by single-fiber composite fragmentation method, a number of fiber breaks of at least 2.0/mm when apparent single-fiber stress is 15.3 GPa and the number of fiber breaks of up to 1.7/mm when the apparent single-fiber stress is 12.2 GPa.

Abstract: An evaluation data collecting system for an information processing system which connects plural processing nodes to each other by communication paths. The evaluation collecting system includes an I/O unit provided at each of the processing nodes so as to input an collection request of the evaluation data for a processing node at issue and other processing nodes and to output the evaluation data from the other processing nodes; a processing unit provided at each of the processing nodes so as to process an input of the collection request for the evaluation data and an output of the evaluation data at said I/O unit; and a storage unit provided at each of the processing nodes so as to provide the evaluation data for each processing node at issue and that for the other processing nodes with a time element to synchronize data transfer between the processing nodes and to store the evaluation data for each processing node at issue and the other processing nodes in substantially the same data format.