Abstract
Graphene oxide (GO) has received wide attention in recent years. GO has been used to enhance the mechanical properties, thermal behavior and morphology of polymers by forming well-dispersed composites. Polyacrylonitrile (PAN) is one of the common polymers used as the precursor for manufacturing carbon fiber in industrial production. This thesis is focused on the effect of GO on the thermal property of PAN and the morphology of the nanocomposite. Well-dispersed PAN/GO composite films were prepared using a solution-casting method. WAXS profiles showed no local aggregation of GO layers in PAN matrix, confirming the good dispersion of GO in the composite. FT-IR spectroscopy suggested that the major interaction between PAN chains and GO molecule was the hydrogen bonding between hydroxyl groups on the surface of GO and the nitrile group on PAN. X-ray diffraction results indicated the degree of crystalling of the PAN was enhanced by around 3-8 % upon the incorporation of GO. The study of the gelation behavior of PAN/GO/DMSO solution containing 4 wt% water revealed that a liquid-liquid phase separation occurred during the gelation with no sign of crystallization and the gelation kinetics was found to be increased by the addition of GO. SDT analysis showed that an appropriate amount of GO may enhance the thermal stability of PAN and the cyclization temperature of PAN was higher in the presence of GO. Furthermore, the kinetic parameters of the cyclization reactions for PAN incorporated with GO were estimated using the Kissinger method. The activation energies of the cyclization reaction for PAN were higher with the existence of GO, implying that GO inhibited the cyclization However, GO may accelerates the cyclization after the cyclized structure was first formed.