Structure Evolution in Polyethylene-Derived Carbon Fiber Using a Combined Electron Beam-Stabilization-Sulphurization Approach

A new approach is described for the production of poly(ethylene) (PE) derived carbon fibers (CFs) that entails the melt spinning of PE fibers from a suitable precursor, their cross-linking by electron beam (EB) treatment, and sulphurization with elemental sulphur (S-8), followed by pyrolysis and carbonization. Instead of focusing on mechanical properties, analysis of CF structure formation during all process steps is carried out by different techniques comprising solid-state nuclear magnetic resonance spectroscopy, thermogravimetric analysis coupled to mass spectrometry/infrared spectroscopy, elemental analysis, energy dispersive X-ray scattering, scanning electron microscopy, Raman spectroscopy, and wide-angle X-ray diffraction. A key step in structure formation is the conversion of PE into poly(thienothiophene)s during sulphurization; these species are stabile under inert gas up to 700 degrees C as confirmed by Raman analysis. Above this temperature, they condense into poly(napthathienophene)s, which are then converted into graphite-type structures during pyrolysis.