PEEK vs PPS: Complete Engineering Comparison (2026) — Temperature, Strength, Cost

Which Material Should You Choose?Choose PEEK (Polyetheretherketone) if:Extreme chemical + thermal environmentsapplications above 200°Cwhere toughness and fatigue resistance are criticalChoose PPS (Polyphenylene Sulfide) if:Cost-sensitive...

PEEK and PPS are both semicrystalline high-performance thermoplastics widely used in demanding chemical and thermal environments. While they share a semicrystalline structure that provides chemical resistance and dimensional stability above Tg, the performance gap between them is substantial — PEEK offers 60°C higher continuous service temperature, 25% higher tensile strength, and dramatically better toughness, while PPS costs 4-6× less and offers superior flow for thin-wall molding.

Property Comparison

Continuous Service Temperature: PEEK: 260°C / PPS: 200°C. PEEK maintains full mechanical properties 60°C higher than PPS, making it the only choice for applications in the 200-260°C range such as oil & gas downhole tools, aerospace engine peripherals, and semiconductor process chambers. Tensile Strength (unfilled): PEEK: 100 MPa / PPS: 80 MPa. PEEK is 25% stronger unfilled. With glass fiber reinforcement (30% GF), the gap narrows: PEEK 30GF ~170 MPa vs PPS 40GF ~180 MPa — at high fiber loadings, PPS can match or exceed PEEK's strength. Impact Toughness: PEEK: Notched Izod 5.5 kJ/m² / PPS: Notched Izod 1.5-2.0 kJ/m². This is the most dramatic difference — PEEK is approximately 3× tougher than PPS. PPS is inherently brittle and notch-sensitive, making it unsuitable for impact-loaded applications. Chemical Resistance: Both materials offer excellent chemical resistance, but with different profiles. PEEK resists virtually all solvents, acids, and bases except concentrated sulfuric acid and halogens. PPS has similarly broad chemical resistance but is attacked by strong oxidizing agents and some chlorinated solvents that PEEK handles well. A key distinction: PPS is resistant to automotive fluids (coolant, brake fluid, transmission oil) at temperatures where other polymers fail — this is why PPS dominates automotive under-hood connectors. Melt Flow & Processability: PPS has exceptionally low melt viscosity — it flows like water compared to PEEK. This makes PPS ideal for thin-wall, high-aspect-ratio parts (electrical connector inserts with 0.3mm wall sections) where PEEK would short-shot. PPS processes at 300-330°C melt / 120-150°C mold; PEEK requires 360-400°C melt / 160-200°C mold — PEEK needs more expensive high-temperature tooling. Moisture Absorption: PEEK: 0.15% (24h) / PPS: 0.02% (24h). PPS has the lowest moisture absorption of any engineering thermoplastic — essentially zero — making it ideal for dimensional stability in humid environments. Cost: PEEK: $80-200/kg / PPS: $15-40/kg. PPS is 4-6× less expensive. For high-volume automotive and electrical applications below 200°C, PPS is the clear economic choice.

Decision Matrix

Choose PEEK When: (1) Service temperature exceeds 200°C continuous — oil & gas, aerospace, semiconductor; (2) Impact toughness and fatigue resistance are critical — PPS is too brittle for cyclic loading; (3) The part contacts aggressive chemicals at elevated temperature where PPS might be attacked; (4) Steam or hydrolysis resistance is required — PEEK is essentially inert to steam at 260°C; (5) Long-term creep resistance at 200°C+ is needed. Choose PPS When: (1) Service temperature is below 200°C and cost is a primary driver — automotive connectors, pump components, sensor housings; (2) Extremely thin-wall molding is required (0.3-0.5mm) — PPS's low viscosity fills these geometries reliably; (3) Dimensional stability in humid environments is critical — PPS's near-zero moisture absorption ensures tight tolerances; (4) Flame retardance is required without additives — PPS achieves UL94 V-0 at 0.4mm inherently due to its limited fuel value; (5) High-volume production where the 4-6× cost difference makes PEEK economically infeasible.

Comparison at a Glance

Equivalents & Cross-References

Related Diagnostics & Materials

References & Industry Standards

• ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
• UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
• MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
• ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org