Poly(acrylonitrile-co-3-ammoniumcarboxylate-3-butenoic acid methyl ester): a better carbon fiber precursor than acrylonitrile terpolymer

Abstract

In order to replace terpolymer with bipolymer, a novel bifunctional comonomer 3-ammoniumcarboxylate-3-butenoic acid methyl ester (ACBM) containing both ester and ammonium carboxylate groups was synthesized to prepare poly(acrylonitrile-co-3-ammoniumcarboxylate-3-butenoic acid methyl ester) [P(AN-co-ACBM)] bipolymer used as carbon fiber precursor. The stabilization and spinnability of P(AN-co-ACBM) and poly(acrylonitrile-methyl acrylate-ammonium acrylate) [P(AN-MA-AA)] was studied by fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetry and rheological analysis. Two parameters \( {E}_s={A}_{1612c{m}^{-1}}/{A}_{2244c{m}^{-1}} \) 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 method and Ozawa method. The results show that the stabilization of P(AN-co-ACBM) has been remarkably improved by ACBM compared with P(AN-MA-AA) terpolymer, such as lower initiation temperature, broadened exothermic peak, larger extent of stabilization and smaller Ea of cyclization. Moreover, the spinnability of P(AN-co-ACBM) is improved by ACBM due to the lubrication of ester groups in ACBM compared with polyacrylonitrile homopolymer. This study clearly shows that P(AN-co-ACBM) bipolymer is a better material used as carbon fiber precursor than P(AN-MA-AA) terpolymer.