An Investigation Of Thermostabilization And Mechanism Of Preoxidized Polyacrylonitrile Fibers Modified Using Hydroxylammonium Chloride

This paper studied the thermal stability process and mechanism of the Hydroxylammonium chorde (HDAC) on polyacrylonitrile fiber preoxidation. With commercial polyacrylonitrile (PAN) as the research object, by gel spinning mechanism for the original silk PAN, then by HDAC modified, and the thermal stability of extension (preoxidation) processing, preparation PAN fiber preoxidation. The FTIR results indicated that the C=N telescopic vibration absorption peaks of the modified PAN preoxidation fiber weakened dramatically, and the C=C and C=N telescopic vibration absorption peaks obvious enhancement, improved cyclization crosslinking degree. DSC thermal analysis found that the melting point and crystallinity of the modified PAN preoxidation fiber samples were significantly reduced with the modified time and the concentration of HDAC increased. With the modification temperature from40℃increased to50℃, the melting point and the corresponding crystallinity decreased. But when modification temperature by50℃rise to90℃, the melting point and instead crystallinity increase gradually. According to the SEM, we found, after the modification, the density of the PAN preoxidation fiber was improved. PAN preoxidation fiber samples modified by the2.5mol/L HDAC, which was the optimal concentration, in the60℃processing of15minutes, its tenacities and elongation at break equal to8.5g/d and12.0%, were the highest than any other samples with the different concentration of HDAC modified. If the PAN preoxidation fiber samples modified by the2.5mol/L HDAC in the50℃processing of15minutes, its tenacities and elongation at break equal to8.8g/d and12.6%, were the highest than any other samples with the different modified temperature. At the same time, PAN preoxidation fiber samples modified by the2.5mol/L HDAC in the50℃processing of5minutes, its tenacities and elongation at break equal to9.6g/d and12.8%, were the highest than any other samples with the different modified time. The mechanism of PAN preoxidation fibers about tensile strengths, FT-IR, and Thermal properties were discussed in this paper.