Study on the Stabilization of Isotropic Pitch Based Fibers

Abstract

Evolution of chemical structure and out gases of isotropic pitch fibers were studied in terms of stabilization. As stabilization plays an important role in the mechanical properties of carbon fibers (CF), thermogravimetric analysis was performed to optimize the duration and temperature of stabilization in this study. Fourier transform-infrared spectroscopy was applied to investigate chemical structure and formation of O-2 containing functional groups during the stabilization. In addition, mass spectrometry showed that O-2 uptake started at around 150 degrees C along with formation of various gases such as CO, CO2, and H2O. The longer stabilization resulted in higher tensile strength of the pitch fiber with higher strain-to-failure due to intermolecular crosslinking reactions leading to a network formation of pitch molecules. The stabilized fibers were carbonized at 1500 degrees C in a furnace under nitrogen atmosphere. Maximum tensile strengths of similar to 900 MPa were obtained from CF stabilized for 60 min at 280 degrees C.