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PI
Material Type
Engineering Plastics
Material Full Name
Polyimide
Process Compatibility
Injection Molding, CNC Machining
Basic Properties
Property |
Parameter/Performance |
Remarks |
|---|---|---|
| Chemical Name | Polyimide | Imide ring (-CO-N-CO-) backbone structure |
| Molecular Structure | Semi-crystalline/amorphous (type-dependent) | Thermoplastic PI (e.g., PEI) vs thermoset PI (e.g., Kapton®) |
| Density | 1.35~1.45 g/cm³ | 50-60% lighter than metals |
| Color | Amber to dark brown (typically opaque) | Film grades can be transparent (>85% transmittance) |
| Mechanical Properties | ||
| – Tensile Strength | 100-200 MPa (film)/150-300 MPa (GF) | Rivals aluminum alloy strength |
| – Elongation at Break | 5-10% (film)/2-4% (GF) | Ultra-high modulus (3-5 GPa) |
| – Wear Resistance | μ=0.2-0.3 (self-lubricating) | Outperforms PTFE at high temps |
| Thermal Properties | ||
| – HDT (1.82MPa) | 260-370℃ (type-dependent) | Highest continuous use temp among polymers |
| – Service Temperature | -269℃~260℃ (short-term 400℃) | Aerospace grades (e.g., PMR-15) withstand 316℃ |
| Chemical Properties | ||
| – Radiation Resistance | >1000 kGy (gamma rays) | Top choice for nuclear reactor components |
| – Chemical Resistance | Resists all organics/acids (except conc. H₂SO₄) | Tolerates 10% NaOH (80℃) |
Processing Characteristics
Thermoset PI:
- Requires high-temp imidization (300-400℃ cure)
- Solution-cast into films (e.g., Kapton®)
Thermoplastic PI:
- Melt temp: 350-450℃ (needs specialized equipment)
- Mold temp: 180-230℃
Special Requirements:
- Oxygen-free processing (prevents oxidation)
Common Application Areas
-
Aerospace: Satellite MLI, rocket engine seals
-
Electronics: IC packaging substrates, 5G flexible antennas
-
Industrial: High-temp filters, bearing cages
-
Medical: Bioabsorbable sutures, neural conduits
PI Modified Types
Type |
Characteristics |
Typical Applications |
|---|---|---|
| Thermoset PI | Insoluble/infusible (e.g., Kapton® films) | Flexible PCBs, spacecraft thermal blankets |
| Thermoplastic PI | Moldable/extrudable (e.g., PEI) | Jet engine parts, 3D-printed high-temp components |
| Carbon-Fiber PI | Thermal conductivity 1.5-2.0 W/mK | Missile nose cones, brake friction materials |
| Conductive PI | Silver/CNT filled (10⁻³-10⁶ Ω·cm) | Anti-static satellite components |
| Medical PI | ISO 10993-1 compliant | Joint implants, vascular stents |
Advantages & Disadvantages
Advantages |
Disadvantages |
|---|---|
| Unmatched heat resistance (260℃+ long-term) | Extremely difficult processing (special equipment required) |
| Inherent flame retardancy (UL94 V0, LOI 45%) | Prohibitively expensive (20-50× PA66 cost) |
| Metal-like dimensional stability (CTE) | Color limitations (difficult to dye light shades) |
Other Engineering Plastics Selection
POM Materials
PA Materials
PC Materials
PET Materials
PEEK Materials
FAQ Of PI Materials
Visit our FAQ center for more questions.
Where is PI irreplaceable in cutting-edge fields?
Critically used in spacecraft thermal shields, nuclear reactor insulation, advanced microelectronics (flexible PCB/chip packaging), and ultra-high-speed bearings (lubrication-free).
Why is PI extremely difficult to process?
PI does not melt (decomposition >500°C), making injection molding impossible. Requires high-temperature sintering or solution-casting film processes, with corrosion-resistant equipment (trace HF release).
What are PI's most extreme performance advantages?
PI offers the highest continuous-use temperature among plastics (300-400°C), exceptional radiation resistance (space-grade), and self-lubricating/wear-resistant properties, with minimal mechanical performance loss across extreme temperatures.