PEEK Fiber
PEEK (polyether ether ketone) occupies a unique position among high-performance fibers: it is the rare HPF that can be melt-spun on modified polyester equipment — no toxic solvents, no complex solution-spinning — yet delivers aerospace-grade thermal stability (continuous service 250°C, Tg 143°C, Tm 343°C), exceptional chemical resistance (attacked only by concentrated sulfuric and nitric acids), and inherent flame resistance (LOI ~35%). Its defining performance advantage is hot-wet stability: PEEK retains >90% strength after 7 days in pressurized steam at 121°C, while meta-aramid loses more than half. Commercialized by ICI as Victrex® in the 1980s, PEEK fiber is produced primarily by ZYEX. Its cost ($80–120/kg) limits it to high-value applications — aerospace wire protection, chemical filtration, medical implants — where its unique combination of melt-processability and extreme environmental resistance justifies the premium.
High-Performance / Melt-Spinnable Thermoplastic Polyether Ether Ketone
Quick Facts
| Type | Semi-crystalline thermoplastic aromatic polyether ketone; rare among HPFs — melt-spinnable |
| Commercialized | 1980s (ICI: Victrex® PEEK); ZYEX is the primary fiber producer; global PEEK resin ~10,000 t/yr |
| Tg / Tm | Tg = 143°C; Tm = 343°C; continuous service ~250°C; the highest-temperature melt-spinnable thermoplastic fiber |
| Density | 1.30 g/cm³ (similar to PET at 1.38) |
| Strength | 0.3–0.4 N/tex (~3.0–4.0 cN/dtex) — comparable to standard PET |
| Key advantage | Melt-spinnable on modified polyester equipment; combines conventional textile processability with extreme chemical/thermal resistance |
Properties
| Property | Rating | Engineering implication |
|---|---|---|
| Hot-wet stability | ★★★★★ | Exceptional; outperforms meta-aramid in pressurized steam (121°C, 7 days: >90% strength retention vs. Nomex® <50%) |
| Chemical resistance | ★★★★★ | Resists almost all organic solvents, acids, and alkalis at room temperature; attacked only by concentrated sulfuric and nitric acids |
| Flame resistance | ★★★★★ | LOI ~35%; self-extinguishing; very low smoke and toxic gas emission; aerospace-qualified FR material |
| Mechanical (vs. PET) | ★★★★☆ | Comparable strength, higher modulus, better creep resistance; adequate for textile processing on standard equipment |
| Cost | ★★★★☆ | $80–120/kg — expensive vs. commodity fibers ($2–5/kg for PET); justifiable only for high-value applications |
Applications
| Application | Form | Key criteria |
|---|---|---|
| Aerospace interiors | PEEK woven fabric or braided sleeving | FR + low smoke/toxicity; lightweight wire harness protection; Airbus/Boeing qualified |
| Chemical / high-temp filtration | PEEK monofilament woven mesh | Corrosive gas filtration >200°C; chemical plant, pharmaceutical, semiconductor |
| Medical implants | PEEK fiber in composite spinal cages, bone plates | Biocompatible, radiolucent (X-ray transparent), modulus similar to bone |
| Industrial brush filaments | PEEK monofilament; 0.1–1.0 mm diameter | Chemical-resistant, high-temp brush bristles; food processing, chemical cleaning |
Summary
PEEK is the rare HPF that can be melt-spun like polyester but performs like a high-temperature engineering plastic — combining textile processability with aerospace-grade thermal and chemical resistance. Its cost premium is the barrier to broader textile use. See the Textile Material framework.