High molecular weight of poly(acrylonitrile- co -3-aminocarbonyl-3-butenoic acid methyl ester) used as carbon fiber precursor: preparation and stabilization

A bifunctional 3-aminocarbonyl-3-butenoic acid methyl ester (ABM) was used to prepare high molecular weight poly(acrylonitrile-co-3-aminocarbonyl-3-butenoic acid methyl ester) [P(AN-co-ABM)] by suspension polymerization in aqueous medium. The influence of ABM monomer feed ratios on the structure and stabilization of P(AN-co-ABM) was characterized by element analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Based on reactivity ratio calculation, the comonomer ABM possesses greater reactivity than acrylonitrile. The molecular weight of P(AN-co-ABM) in this work is 10 times larger, as compared to the one prepared by solution polymerization; it is the key to producing high-performance carbon fiber. The FTIR, XRD and DSC results illustrate that the stabilization of P(AN-co-ABM) is significantly improved as compared with PAN homopolymer and P(AN-AA-MA), for instance, lower initiation temperature, smaller cyclization activation energy (Ea), broadened exothermic peak and larger stabilization extent, due to the ionic cyclization initiated by ABM, which makes the resultant P(AN-co-ABM) a potential precursor for carbon fiber.