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Free-radical solution copolymerization of itaconic acid and acrylonitrile was carried out in DMSO using azodiisobutyronitrile as an initiator, changing the feed rate of itaconic acid. The resulting polymerization solution was spun to form polyacrylonitrile (PAN) precursors of carbon fibers. The precursors were treated with a CoSO 4 aqueous solution on-line. The structure and properties of untreated and treated PAN precursors and the resultant carbon fibers were characterized by SEM and TEM, a stabilization process, etc. It is suggested that CoSO 4 acts as a catalyst in the formation of a ladder structure and reduces the temperature of cyclization, and the carbon fibers developed from treated PAN fibers showed improvement in the tensile strength and the Young's modulus.

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Polyacrylonitrile (PAN) copolymers containg photocrosslinkable comonomer were obtained by the free-radical suspension copolymerization of Ultraviolet photocrosslinkable comonomer (UPC), methyl acrylate (MA) and acrylonitrile (AN) that was carried out in DMSO/H2O using redox as initiator in which have a typical composition of AN/MA/UPC in the mole ratio of 84/15/1. It was shown that MA was found to be suitable for enabling the melt processing of PAN. The ultraviolet sensitivity of UPC moiety improves the ultraviolet crosslinkability of the precursor fibers, as a result, the melt spun precursor fibers after ultraviolet irradiated can be oxidatively stabilized at 310 oC without melting and subsequently carbonized. The resultant carbon fibers with tensile strength of 602.2±151.3 MPa and modulus of 7.32±0.78 GPa were obtained.