Polyacrylonitrile-based (PAN-based) Carbon Fibers: PAN-based carbon fibers are formed from polyacrylonitrile through several stages: spinning, pre-oxidation, and carbonization. The technology for preparing precursor fibers primarily encompasses the precursor production phase and the subsequent oxidation and carbonization phases. Within the precursor production phase, spinning methods are categorized into wet spinning and dry-jet wet spinning, while the production of the polymerization solution is classified into one-step and two-step processes. Dry-jet wet spinning is a critical process for high-performance carbon fibers-such as the T1000 grade-and involves extruding a polymer dope through a spinneret, allowing it to travel briefly through an air gap, and then immersing it into a coagulation bath. These fibers are characterized by high strength, high stiffness, light weight, high-temperature resistance, corrosion resistance, and specific electrical properties; they exhibit excellent compressive and flexural performance and are widely utilized in reinforced composite materials.
Pitch-based Carbon Fibers: Pitch-based carbon fibers are manufactured using petroleum pitch or coal pitch as raw materials, undergoing a process involving pitch refining, spinning, pre-oxidation, and either carbonization or graphitization. The precursor pitch is classified into two types: isotropic and anisotropic (mesophase). Isotropic pitch is typically melt-blown or melt-spun into chopped fibers, whereas mesophase pitch can be melt-spun into continuous fibers, although the spinning process for the latter is technically more challenging. The cost of raw materials for pitch-based fibers is lower than that for PAN-based carbon fibers.
Rayon-based Carbon Fibers: Rayon-based carbon fibers are derived from rayon fibers-which consist primarily of cellulose-through a process involving dehydration, pyrolysis, and subsequent carbonization.
Vapor-Phase Grown Carbon Fibers: Vapor-phase grown carbon fibers are synthesized using raw materials such as benzene or methane, utilizing transition metals (e.g., iron, cobalt, nickel), their alloys, or their compounds as catalysts, and employing hydrogen gas as a carrier gas within a reducing atmosphere.
Research into novel precursors includes the development of lignin-based carbon fiber precursors and bio-based raw materials (such as acrylonitrile/guanidine crotonate copolymers), with the aim of either reducing production costs or enhancing performance .
The preparation of precursor fibers constitutes a critical stage in carbon fiber production, accounting for nearly half (approximately 51%) of the total production cost . Process optimization (such as the control of coagulation bath parameters and draw ratio) is crucial to the properties of the precursor fiber.
