PURPOSE: To obtain carbon fiber having a high elongation and an isotropic crystal structure and a method for producing the carbon fiber.
CONSTITUTION: This high-elongation carbon fiber has values of physical properties of 2.5-4.0% elongation, 100-400kg/mm2 tensile strength and 3.5-10.0ton/mm2 elastic modulus and is X-ray diffractometrically amorphous without manifesting a 002 X-ray diffraction line by the X-ray diffractometry and this method for producing carbon fiber having the characteristics is to divide the heat treatment of carbon fiber precursor filaments into two stages, apply a proper stretching force in each stage and heat-treat the filaments while suppressing the drawing or shrinkage. This carbon fiber is one having excellent characteristics as reinforcing fiber for various composite materials and the time required for the heat treatment can be shortened to simplify the process.
HARA YOICHIRO
KAKEBAYASHI HIROSHI
