Study on the relationships of mechanical performance with the short-range and long-range structure of 500–900℃ carbonized fiber

The relationships of mechanical performance with the short-range and long-range structure of 500–900℃ carbonized fibers were studied by the combination of radial distribution function (RDF), Fourier transform infrared spectroscopy (FT-IR) and high-resolution transmission electron microscopy (HRTEM), etc. In the range of 500–900℃, there were different laws of change for tensile strength and elastic modulus during different temperature stages. The tensile strength was more nearly directly proportional to temperature, especially at higher than 600℃. The elastic modulus increased slowly from 500 to 700℃, and then elastic modulus increased rapidly after 700℃. The short-range structures had no effects on the mechanical performance. The uniform increasing rate of tensile strength was closely related to the crystallinity degree and crystal size. The outstanding increase of orientation degree was closely related to the change of elastic modulus.