การผลิตเส้นใยคาร์บอนจากโพลีอะคริโลไนไตรล์

วัสดุระดับอวกาศที่แข็งแกร่งกว่าเหล็กสิบเท่า

Materials Science & Polymers Commercial Production $5.8 billion

ภาพรวม

Carbon fiber is produced by the controlled thermal conversion of polyacrylonitrile (PAN) precursor fiber through oxidation, carbonization, and graphitization steps. The resulting fiber has a tensile strength 10 times that of steel at one-fifth the weight, making it essential for aerospace, automotive, wind turbine blades, and sporting goods. PAN accounts for over 90% of all carbon fiber precursor, with Toray, Teijin, and SGL as major producers.

กระบวนการทางเคมี

PAN precursor fiber is stretched and stabilized in air at 200-300 degrees C (oxidation), forming a thermally stable ladder polymer. The stabilized fiber is carbonized at 1,000-1,500 degrees C in nitrogen, removing non-carbon elements. Optional graphitization at 2,000-3,000 degrees C further increases modulus. The fiber is surface-treated and sized for composite compatibility.

PAN (CH2-CH(CN))n ->[200-300 degrees C, air] Stabilized ladder polymer (cyclization + oxidation)
Stabilized fiber ->[1,000-1,500 degrees C, N2] Carbon fiber + HCN + H2O + N2 (carbonization, >95% C)

วัตถุดิบ

Polyacrylonitrile (PAN) precursor fiber — Wet or dry-jet spinning of PAN copolymer (Carbon fiber precursor (>90% of production))
Nitrogen gas (N2) — Air separation unit (cryogenic) (Inert atmosphere for carbonization)

ผลิตภัณฑ์สำเร็จรูป

Carbon fiber tow — Aerospace composites, automotive, wind turbines, sporting goods (3K-48K filament count, tensile modulus 230-600 GPa)

Environmental Impact

Carbon fiber production is extremely energy-intensive (~200 GJ/ton) and generates HCN as a toxic byproduct during carbonization. CFRP waste is difficult to recycle, though pyrolysis-based recycling is emerging. The high cost and energy input limit adoption outside high-performance applications.

ข้อควรพิจารณาด้านความปลอดภัย

⚠ HCN generation during stabilization and carbonization -- lethal gas
⚠ High-temperature furnaces (up to 3,000 degrees C)
⚠ Carbon fiber dust is electrically conductive -- short circuit risk in electronics
⚠ Fiber fragments cause skin irritation (mechanical, not chemical)

นวัตกรรมล่าสุด

Microwave and plasma-assisted carbonization can reduce energy consumption by 50%.
Bio-based precursors (lignin, cellulose) are being developed as cheaper, renewable alternatives to PAN.
Recycled carbon fiber from pyrolysis of CFRP waste is entering the market for non-critical applications.