Abstract:On the basis of the theory of modulus, the mathematic function of the modulus with parameters of
pseudo-graphite crystallite for carbon fiber was derived. The results indicated that the crystalline modulus of carbon
fiber was affected by the shape factor and the orientation angle. With the increasing of shape factor, the crystalline
modulus of carbon fiber was rised up firstly and then decreased. While the orientation angle was decreased, the modulus
was increased. The calculated modulus of carbon fiber from crystalline parameters, which was obtained from X-ray
diffraction analysis, was closed to the measured value. It means the equation was satisfied the structure dependence of
the modulus for carbon fiber
