Ultra-High Performance
Plastics Difference Guide
Deep analysis of PI, PAI, PEEK, and PEI for aerospace, semiconductor, and medical applications.
Engineered for the extremes of thermal and mechanical stress.
PI
The king of heat resistance and electrical insulation. Widely used for films and precision bearings.
PAI
Unmatched in mechanical strength, wear resistance, and high-temperature rigidity. The top choice for high-load bearings and seals.
PEEK
Offers the best balance of chemical resistance, self-lubrication, and semi-crystalline stability. A classic choice for Oil & Gas and medical implants.
PEI
The leader in cost-effectiveness, transparency, and processability. A mainstay for high-end applications in aerospace and electronics.
Basic Definitions & Structural Comparison
| Property | PI (Polyimide) | PAI (Polyamide-imide) | PEEK (Polyetheretherketone) | PEI (Polyetherimide) |
|---|---|---|---|---|
| Crystallinity | Semi-crystalline / Amorphous (Grade dependent) | Amorphous | Semi-crystalline | Amorphous |
| Appearance | Dark Brown / Black (Opaque) | Amber / Black (Translucent) | Beige / Black (Opaque) | Transparent Amber / Black (High Transparency) |
| Typical Tg / Tm | Tg >300°C / Decomposes ~500°C | Tg 275°C / No distinct Tm | Tg 143°C / Tm 343°C | Tg 217°C / No Tm |
| Processing Trend | Thermoset-like (Requires post-curing) | Melt-processable (Requires post-curing) | Typical Thermoplastic | Typical Thermoplastic |
Performance Characteristics Comparison
| Property | PI | PAI | PEEK | PEI | Ranking (High to Low) |
|---|---|---|---|---|---|
| Continuous Service Temp | 260-300°C+ (Short 500°C) | 260°C | 250°C (Short 300°C) | 170-180°C (Short 210°C) | PI > PAI > PEEK > PEI |
| HDT (1.8MPa) | 300°C+ (Higher if filled) | 270-280°C | 250-320°C (Filled) | 190-210°C | PI > PAI > PEEK > PEI |
| Tensile Strength (MPa) | 80-120 | 190-220 (Highest) | 90-110 | 100-120 | PAI >> PEI ≈ PI > PEEK |
| Notched Impact Strength | Med - High | High (Great Toughness) | Med - High | High (Excellent) | PAI ≈ PEI > PEEK ≈ PI |
| Compressive Strength / Rigidity | Extremely High | Highest (2x PEEK) | High | High | PAI > PI > PEEK ≈ PEI |
| Chemical Resistance | Excellent | Excellent | Extreme (Conc. H₂SO₄ only) | Good - Excellent | PEEK > PAI ≈ PI > PEI |
| Wear / Friction Coeff. | Excl. (Best at high temp) | V. Good (Lowest if modified) | V. Good (Bearing King) | Average | PAI ≈ PEEK > PI > PEI |
| Dimensional Stability / Creep | Excellent | Excellent | Excellent | Excellent | PI > PAI ≈ PEEK ≈ PEI |
| Transparency / Processing | Fair (Film only) / Difficult | Translucent / Med (Post-cure) | Opaque / Good | High Transp / Best (Easy IM) | PEI > PEEK > PAI > PI |
| Flame Retardancy | V-0 Inherent | V-0 Inherent | V-0 Inherent | V-0 Inherent | All Equivalent |
Application Scenario Comparison
| Material | Core Advantages | Typical Applications | Market Positioning |
|---|---|---|---|
| PI | Ultimate heat resistance, electrical insulation, and aerospace extremes. | Aero-engine insulators, Kapton flexible circuits, semiconductor wafer rings, high-precision bearings, rocket nozzles. | Premier choice for Aerospace, Semiconductor, and High-temp Films. |
| PAI | Superior strength, high-temp wear resistance, and reliable sealing. | Aerospace hydraulic pumps, automotive turbo impellers, oil-drilling seals, bearing cages, medical instruments. | High-end Aerospace, Oil & Gas, and Precision Bearings. |
| PEEK | Optimal chemical resistance, self-lubrication, and biocompatibility. | Oil & Gas valves, medical implants/screws, semiconductor wafer carriers, automotive gears, food processing parts. | Mainstream leader for Oil & Gas, Medical, and Automotive. |
| PEI | Cost-effective, transparent, easy processing, and aerospace certified. | Aircraft interior panels, medical instrument handles, electronic connectors, LED reflectors, water filtration supports. | High-to-Mid-end Aerospace, Electronics, and Medical. |
Quick Material Selection Decision Form
(One-Sentence Summary)
| Your Core Requirement | Top Choice | Quick Reason |
|---|---|---|
| Highest Heat + Electrical Insulation + Film/Aerospace | PI | "The Heat Ceiling" – Exceptional performance, though hardest to process. |
| Max Mechanical Strength + High-temp Wear + Sealing | PAI | "King of Strength & Wear" – The classic Torlon® standard. |
| Best Chemical Resistance + Self-lubrication + Bio-compat | PEEK | "The All-Rounder" – Top pick for Oil & Gas and Medical implants. |
| Cost-effective + High Transp + Easy IM + Aero-Certified | PEI | "The Smart Choice" – The Ultem® value-performance king. |
| Limited Budget but Needs 180°C+ Heat Resistance | PEI | Most affordable high-performance polymer option. |
| Needs Ultimate Strength or High-temp Bearings | PAI / PI | PAI for easier machining; PI for extreme environments. |
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