Molecular design and stabilization mechanism of acrylonitrile bipolymer

In order to replace terpolymer with bipolymer, a bifunctional comonomer 3-aminocarbonyl-3-butenoic acid methyl ester (ABM) was synthesized for preparing poly(acrylonitrile-co-3-aminocarbonyl-3-butenoic acid methyl ester) [P(AN-co-ABM)] bipolymers as carbon fiber precursor. The structure and stabilization of P(AN-co-ABM) bipolymers were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry. The monomer reactivity ratios were calculated by the Fineman-Ross and Kelen-Tudos methods, and the results show that ABM displays higher reactivity than acrylonitrile. Two parameters Es = A1618cm-1/A2244cm-1 and SI = (I0 - Is)/I0 were defined to evaluate the extent of stabilization, and the activation energy (Ea) of the stabilization reactions were calculated by Kissinger and Ozawa methods. The results show that the P(AN-co-ABM) bipolymers exhibit significantly improved stabilization performance when compared with polyacrylonitrile (PAN) homopolymer, such as lower cyclization temperature, lower Ea, and larger extent of stabilization under the same conditions. Simultaneously, the rheological analysis shows that P(AN-co-ABM) possesses better spinnability than PAN. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013