Influence of Comonomer Feed time Control in Copolymerization of Polyacrylonitrile and Evaluation Its Solutions

Abstract

The mechanical properties and microstructure of polyacrylonitrile (PAN)-based carbon fibers are strongly influenced by the properties of PAN precursor. The precursor properties are intricately determined by the molecular weight, co-monomer composition, and processing parameters during the spinning process. The most widely used polymerization methods of PAN copolymers include solution polymerization and suspension polymerization. Among them, solution polymerization has the advantage of high yield due to the good solubility of the monomer in organic solvents like dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and dimethylacetamide (DMAC), and can be directly utilized as a spinning dope. Usually, in PAN copolymers, the content of the co-monomer can be up to 5%. [1] The effect of comonomers in PAN copolymers varies depending on their type, for example, acidic comonomers increase hydrophilicity and reduce the cyclization temperature during the stabilization step. [2] A reactivity ratio difference between acrylonitrile (AN) and acidic comonomers can have an impact on the composition and microstructure of the PAN copolymer. In other words, the microstructure and properties of PAN-based carbon fibers will also be affected. In this study, we prepared poly(acrylonitrile-co­methacrylic acid) with controlled methacrylic acid(MAA) feed time. The properties of each PAN copolymer were investigated, and for the production of PAN precursor fiber, the spinnability of each PAN copolymer solution was evaluated by rheological properties.