Fiber-Forming Acrylonitrile Copolymers: From Synthesis to Properties of Carbon Fiber Precursors and Prospects for Industrial Production

Non-Coagulant Spinning of High-Strength Fibers from Homopolymer Polyacrylonitrile Synthesized via Anionic Polymerisation

“…Polyacrylonitrile (PAN) is one of the most important industrial polymers. Synthetic fibers obtained from PAN and its copolymers have a set of properties, including resistance to main organic solvents, high mechanical strength, and many others [1,2]. First of all, PAN staples are used as a wool-like material and found a major application in mixing with natural wool.…”

“…Moreover, PAN has the greatest practical importance as a precursor of carbon fibers. This is due to the high specific strength and fiber stiffness, as well as the high carbon yield during carbonization [2,5]. In this case, the properties of the final product largely depend on the chemical structure and molecular weight of the initial polymer, which is determined primarily by the synthesis conditions.…”

“…Anionic polymerization is interesting primarily because of the absence of chain termination and chain-transfer reactions. The synthesis of PAN by the anionic mechanism is characterized by a high yield of polymers, the possibility of carrying out the reaction at high rates, and control of the polymer molecular weight distribution [2,13,14]. The initiators of the anionic polymerization of acrylonitrile are alkali metals, as well as compounds based on them, such as alcoholates, amides, and hydroxides [14,15].…”

“…Typically, to produce carbon fibers, PAN ternary copolymers containing carboxy groups are used to expand the exothermic peak during the thermal-oxidative stabilization process when the cyclization of nitrile groups is being [2,[24][25][26][27] and alkyl acrylates to increase spinnability, because PAN homopolymers are more prone to gelation due to nitrile-nitrile interactions, which prevent chains from orienting during stretching [16,28,29]. However, such monomers do not participate in the formation of the polyconjugated system at this stage, and their presence can contribute to the uneven cyclization of PAN and the formation of defects [30,31].…”

Evolution of polyacrylonitrile precursor fibers and the effect of stretch profile in wet spinning

“…To attain carbon fiber property targets, focus has been turned to precursor development and fiber spinning, which establishes the structure and morphology of the carbon fiber at the nascent stages 12–16 . Precursor structure is influenced by chemical composition, 17,18 fiber denier and crystallinity, 19 fibril structure and alignment, 20–22 and spinning speeds 21 .…”