| In this paper polyacrylonitrile copolymers used to produce carbon fiber with high performance were obtained by aqueous deposited polymerization. Acrylamide (AM) and itaconic acid (IA) were chosen as the second and third comonomer respectively. Ammonium persulfate (APS) was used as the initiator agent for it has no alkali metal ions. Reaction temperature and time, pH value, initiator system, comonomer concentration, chain transfer agent and terminator were studied to determine the appropriate polymerization conditions. Effects of comonomers on the performance and spinning solution of PAN such as AN/AM reactivity ratio, molecular chain structure, thermal properties and rheological behavior were discussed, which were characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), X-ray diffraction (XRD), thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR) and R/SCC coaxial cylinder rheometer.Copolymers with high conversion ratio and suitable molecular weight could be manufactured by controlling reaction conditions as fllows:the temperature was between 60 to 65℃, the reaction time was 2 hours, the initiator agent concentration was 0.8wt%, AM was less than 2wt%, while IA was lwt%; ammonium sulfite (AS) was chosen as the reductant in the complex initiation system while the molar ration of APS and AS should be betwween 2:1 to 1:1; ethanolamine (EOA) was better than others as chain transfer agent; N-Ethyl-N-hydroxy ethanamine (DEHA) could serve as the termination agent and moreover the concentration should be 2wt‰of the whole monomer amount.Reactivity ratio of AN/AM was caculated with elemental analysis. The result was:rAN=0.9028, rAM=1.397 by KT method and rAN=0.9043, rAM=1.410 by YBR method. The average sequence length of PAN copolymer was seriously influnced by the feed of AM.Stretching vibration of acylamino group and carboxyl group (C=O) emerged with the introduction of AM and IA respectively. The assignment of methane carbon spectra with triad was studied by 13C-NMR spectra. It showed that the largest share, about 50% of triad in molecular chain was the heterotactic structure. The stereoregularity would reduce a little while AM and IA were introduced. The crystallinity would increase and then reduce with the raise of AM in the feed, but the crystallite dimension decreased all along, while both of them declined as IA concentration increased, which had obvious fall.The analysis of DSC, TG and FTIR showed the introduction of AM and IA could lower the initial reaction temperature, generated double peaks and three peaks in DSC curves, broadened the exothermic peak, decreased the weight loss, and alleviated the exothermic reaction, all of which would improve the property of PAN precursor. During the pre-oxidation process the stretching vibrations of nitrile group (C=N) and methane group (CH2) decreased and nearly disappeared while double bond groups such as C=C and C=N, which represented the ladder structure appeared and became stronger gradually. Meantime the dope of C=N group in copolymer decreased more quickly than that in homopolymer by degrees.The investigation on the PAN spinning solution rheology showed that the viscosity and the structure viscous index became higher, the Non-Newtonian index was smaller and the physical stability was worse while the molecular weight and solution concentration became higher. Molecular weight had greater impact on rheological performance of P(AN-co-AM) copolymer. The solution was temperature-sensitive with low molecular weight but tended to be shearing-sensitive with the higher one. The solvency of solvents to PAN was tested as follows: dimethyl formamide (DMF)> dimethylacetamide (DMAc)> dimethylsulphoxide (DMSO) while the sensitivity to temperature was opposite. The study showed when the molecular weight was about 2×105, the spinning temperature was 353K and the solvent was DMAc, we can get good spinning solution.
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