Characterization of effect of conventional and microwave assisted plasma (MAP) manufacturing processes on surfaces of pan based carbon fibers

The effects of processing parameters in conventional and Microwave Assisted Plasma (MAP) processes on the chemical and physical characteristics of PAN based carbon fibers were studied. X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope (SEM) and Small Angle X-Ray Scattering (SAXS) were used to study the hypothesis that comparable fibers could be produced much faster and more cost effective by the MAP process as could be made by conventional processes. The chemical composition and functional groups on the surface of the fibers were determined using XPS to compare the chemistry of fibers from the two processes. The SEM was used to observe the surface topography of individual fibers and to compare fracture surfaces of broom-straw composite specimens made from fibers from each process. SAXS was used to measure the porosity of the fibers. The MAP fibers were compared to the untreated unsized graphitized fibers from the conventional manufacturing process. XPS revealed very similar chemical compositions for the manufacturing process. However, the functional groups on the surface were not the same. The conventional manufacturing process had a larger variety of oxygenated functional groups than the MAP fibers contained. SEM studies revealed similar topography for the surface of the fibers including large quantities of micro-ridges that were present on both the MAP and conventional fibers. And broom-straw type fracture tests revealed less pull out for the MAP fibers than for the conventional fibers. So the MAP fibers with low-level surface treatment created equivalent or better adhesion than the conventional fibers with surface treatment. A comparison of porosity values from SAXS also provided comparable results. Statistically the values of the porosity could not be distinguished.