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Tuba Demirel,Md. Mahbubor Rahman,Kemal Şahin Tunçel,Ismail Karacan 한국섬유공학회 2022 Fibers and polymers Vol.23 No.11
Thermal-oxidative stabilization of polyacrylonitrile (PAN) fiber pretreated with ammonium bromide (NH4Br) wasperformed in the air atmosphere at temperatures between 200 and 250 °C for periods of 5 to 75 min in a multistep approach. The study demonstrates that the NH4Br incorporation is highly effective in accelerating nitrile group cyclization by reducingthe time required to form a thermally stable structure. After 60 min of the multistep stabilization, NH4Br incorporated andstabilized PAN was entirely thermally stable, infusible, and non-burning. XRD analysis showed the conversion of the pristinePAN molecular structure from a laterally ordered condition to a very disordered amorphous structure by crosslinking andaromatization process. Infrared analysis indicated rapid and concurrent aromatization and dehydrogenation reactions assistedby the formation of oxygen-containing functional groups. With the progression of the stabilization period, TGA thermogramsrevealed a comparative increase in thermal stability, as directed by the continuous rise of carbon yield. By decreasing therequired time for the stabilization process of PAN fiber, the use of NH4Br impregnation is expected to enhance carbon fiberproductivity at a reduced cost considerably.
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