RecommendedRecommend

hot keywordsKeywords

Contact UsContact Us

Hebei Carbon Valley Carbon Fiber Co., Ltd

Manager Hao (pre oxygenation thread): 13831164999

Manager Shi (pre oxygenation wire): 17332928150

Manager Gu (Pre oxygenation Silk): 13833138900

Manager Zhao (woven fabric, pre impregnated fabric, prefabricated body): 15028196018

Manager Zhang (woven fabric, axial fabric): 13703314888

Manager Zhao (Composite Products): 13944687090

Address: 226 Shifu East Road, Gaocheng District, Shijiazhuang City, Hebei Province

What is the chemical stability of pre-oxidized fiber?

2026-01-30 17:51:11

10139

Pre-oxidized fiber (a key intermediate in carbon fiber production, typically derived from polyacrylonitrile (PAN), pitch, or rayon precursors) exhibits excellent chemical stability overall, with its resistance to chemical degradation, corrosion, and solvent dissolution far superior to its unoxidized precursor fibers, and this stability is a foundational characteristic that enables its subsequent carbonization into high-performance carbon fiber. Its chemical stability stems from the profound structural transformations during the pre-oxidation process—under controlled thermal treatment (200–300 °C in air for PAN-based fibers), the precursor’s linear macromolecular chains undergo a series of irreversible reactions including cyclization, dehydrogenation, oxidation, and cross-linking, forming a rigid, thermally stable heterocyclic network structure with conjugated double bonds and oxygen-containing functional groups (e.g., C=O, –OH, –COOH). This cross-linked aromatic heterocyclic framework eliminates the weak intermolecular forces and reactive aliphatic segments of the original precursor, making the fiber highly resistant to chemical attacks that break covalent bonds or disrupt molecular structure.

In terms of resistance to acids and alkalis, pre-oxidized fiber shows good tolerance to most inorganic acids (e.g., dilute sulfuric acid, hydrochloric acid, nitric acid) and weak alkalis under ambient temperature and moderate concentration conditions; the heterocyclic structure is not easily hydrolyzed or protonated by these media, and the fiber’s physical form (shape, mechanical strength) remains largely unchanged. It has limited resistance to strong concentrated alkalis (e.g., hot concentrated NaOH, KOH) and oxidizing strong acids (e.g., fuming sulfuric acid, concentrated hot nitric acid), as prolonged exposure to these harsh conditions can cause partial cleavage of the cross-linked network or oxidation of residual reactive sites, leading to slight surface etching or a small reduction in mechanical properties, but complete dissolution or structural collapse is still unlikely—this is a critical difference from unoxidized PAN fibers, which are readily soluble or degraded in strong acids/alkalis.

For organic solvents, pre-oxidized fiber is nearly insoluble and infusible in all common organic solvents, including polar solvents (e.g., DMF, DMSO, NMP—solvents that readily dissolve raw PAN powder/fibers), non-polar solvents (e.g., benzene, toluene, hexane), and polar protic solvents (e.g., methanol, ethanol, water). The cross-linked three-dimensional network structure prevents solvent molecules from penetrating the fiber’s internal macromolecular chains and disrupting intermolecular interactions, so the fiber does not swell, dissolve, or plasticize in organic solvents, even at elevated temperatures. This solvent resistance is a core advantage of pre-oxidized fiber in industrial processing, as it can be subjected to subsequent carbonization, graphitization, or surface modification without being damaged by organic media.

In oxidizing and reducing environments, pre-oxidized fiber has moderate oxidation resistance at ambient temperature: the oxygen-containing functional groups on its surface have already undergone partial oxidation during pre-oxidation, so it is not easily further oxidized by air, weak oxidants (e.g., hydrogen peroxide, sodium hypochlorite) at room temperature, and can maintain structural stability for long periods in atmospheric conditions. At high temperatures (>300 °C), however, it will undergo further oxidative degradation in the presence of oxygen (this is why carbonization is carried out in an inert atmosphere), but its high-temperature oxidation resistance is still far better than unoxidized precursors. In reducing environments (e.g., H₂, CO), pre-oxidized fiber is stable at low to moderate temperatures; at high temperatures (above the carbonization temperature), partial oxygen-containing functional groups are reduced and removed (a key step in carbonization to increase carbon content), which is a controlled chemical change rather than random degradation.

Additionally, pre-oxidized fiber is resistant to hydrolysis and microbial degradation: the absence of easily hydrolyzable groups (e.g., ester, amide linkages in the original precursor) and the rigid cross-linked structure make it unaffected by water, humidity, or microbial activity, even in long-term wet or corrosive industrial environments, without aging, rotting, or structural damage. Its chemical stability is also accompanied by thermal stability (it does not melt or soften below 300 °C) and dimensional stability, forming a comprehensive performance system that supports its industrial applications not only as a carbon fiber precursor but also as a standalone high-temperature resistant, corrosion-resistant fiber for fireproof materials, filter media, and high-temperature sealing components.

It is important to note that the chemical stability of pre-oxidized fiber is precursor-dependent and process-tunable: PAN-based pre-oxidized fibers generally have better overall chemical stability (especially acid/alkali and solvent resistance) than pitch-based or rayon-based ones due to their more complete cyclization and cross-linking reactions; the pre-oxidation temperature, holding time, and air flow rate also affect the degree of structural cross-linking—higher pre-oxidation completeness leads to a more rigid network and better chemical stability, while incomplete pre-oxidation leaves residual reactive segments, slightly reducing resistance to harsh chemicals. In summary, pre-oxidized fiber’s chemical stability is a result of its unique cross-linked heterocyclic structure, making it a chemically robust intermediate material with far better resistance to degradation than precursor fibers and laying the groundwork for the ultra-high chemical stability of the final carbon fiber.