Thermoplastic Polyimide (TPI): The Ideal Combination of High-Temperature Performance and Excellent Processability

Thermoplastic Polyimide (TPI) is an advanced material that combines ultra-strong high-temperature resistance with the melt-processability of common engineering plastics. Simply put, it solves the problem of traditional polyimides, which, despite their excellent performance, are difficult and costly to process. If you need to manufacture parts that must operate at extreme high temperatures, have complex shapes, and require precise tolerances (such as bearings, seals, electronic components), TPI allows you to achieve this more efficiently and economically.

Advantages

Performance Advantages of Allstar Material's Thermoplastic PI

It resists high temperatures, supports efficient molding, and maintains strength, rigidity, and wear resistance. It also offers chemical, radiation, and flame resistance, plus excellent insulation.

Exceptional High-Temperature Performance

Exceptional High-Temperature Resistance
The high-temperature resistance of Thermoplastic Polyimide (TPI) is exceptional. Its Glass Transition Temperature (Tg) typically ranges from 250°C to 350°C. Its Continuous Use Temperature (CUT) generally reaches 240°C to 300°C, allowing long-term stable operation at these temperatures without significant loss of mechanical, electrical, or other key properties. This thermal stability makes TPI ideal for replacing metals or other high-performance plastics in extreme heat environments.

Melt Processability

Thermoplastic Processability of TPI Unlike traditional thermosetting polyimides, TPI can melt and flow at high temperatures. This allows it to be processed using standard thermoplastic methods such as injection molding and extrusion. Processing temperatures are typically high, generally in the range of 350°C to 420°C, depending on the grade. This enables TPI to be used for manufacturing precision components with complex geometries, expanding its application range and allowing for high-volume, cost-effective production, which is difficult to achieve with traditional PI.

Excellent Mechanical Strength and Wear Resistance

TPI Mechanical & Tribological Performance
TPI offers tensile strength of 120–180 MPa and flexural modulus of 4–6 GPa (unreinforced), ensuring stability under high loads. Self-lubricating grades achieve low friction (0.1–0.3 vs. steel) and minimal wear (low K factor). High PV limits (>1.5–2.5 MPa·m/s) enable reliable, long-term use in high-load, high-speed applications like bearings and seals.

Note: Actual values depend on TPI grade, fillers, and test conditions. Figures are typical ranges.

Good Chemical Inertness and Radiation Resistance

Chemical Resistance:
TPI resists organic solvents, fuels, oils, weak acids, and bases, ensuring stable performance in harsh chemical environments.

Radiation Resistance:
TPI withstands gamma ray doses up to 1 × 10⁷ Gy (or 1 × 10⁹ Rad) with minimal degradation, ideal for nuclear, aerospace, and radiation sterilization uses.

(Performance may vary by grade, temperature, exposure time, and radiation type.)

Flame Retardancy

UL 94 Rating:
Unreinforced TPI typically achieves UL 94 V-0, even at 0.8–1.6 mm, meaning it self-extinguishes quickly without dripping.

Limiting Oxygen Index (LOI):
Generally above 35% (some grades over 40%), indicating high flame resistance and low combustibility.

Low Smoke & Toxicity:
Produces low smoke and fewer toxic gases when burned, making it suitable for aerospace, transport, and enclosed spaces.

Electrical Insulation

Dielectric Strength:
TPI typically offers 15–25 kV/mm (ASTM D149), ensuring excellent high-voltage resistance.

Volume Resistivity:
Exceeds 10¹⁶ Ω·cm (ASTM D257), minimizing current leakage through the material.

Surface Resistivity:
Also above 10¹⁶ Ω/sq (ASTM D257), preventing surface current leakage.

Dielectric Constant & Dissipation Factor:
Low and stable εr (3.0–3.5 @ 1 MHz) and very low tan δ (<0.003 @ 1 MHz), ideal for high-frequency and microwave uses with minimal loss.

Processing

Processing of Allstar Material's Thermoplastic Polyimide (TPI)

Allstar Material's Thermoplastic Polyimide (TPI) is processed using standard methods like injection molding, extrusion, and compression molding, with a typical processing temperature of 350–400°C due to its high melting point.

Injection Molding

Injection molding efficiently produces complex TPI parts. Pre-dried TPI pellets (dried at 150°C–200°C) are fed into a heated barrel (350°C–400°C), melted, and injected into precision molds under high pressure. Mold temperatures (150°C–230°C) ensure good crystallinity, stability, and minimal stress. Due to TPI’s high viscosity, high pressures and speeds are needed. Parts may undergo post-annealing. Equipment must handle high temperatures.

Extrusion

Extrusion forms continuous TPI profiles like rods, tubes, and films. After pre-drying, pellets are melted in the extruder (350°C–400°C) and shaped through a die. The profile is cooled and drawn at a steady speed, with TPI’s high melt strength aiding shape retention. The process demands heat-resistant extruders, dies, and screws designed for TPI’s properties.

TPI Compression Molding

Compression molding suits thick parts and small-batch TPI production. Pre-dried powder or preforms are placed in a heated mold (360°C–400°C) and compressed under high pressure. Heat and pressure are maintained to melt, fill, and compact the material. Cooling may occur under pressure or in a cold press. Though simple, this method has longer cycles.

Applications

Thermoplastic Polyimide (TPI) Applications

Thermoplastic Polyimide (TPI), with its excellent comprehensive properties, is widely used in several demanding fields. The following are some major application areas:

Aerospace & Defense

Engine Components: Used to manufacture some non-structural high-temperature components in jet and rocket engines, such as insulation parts, low-friction bushings, and seal rings.

Connectors & Cables: Due to its excellent electrical insulation, high-temperature resistance, and flame retardancy, used for manufacturing high-performance connectors, sockets, and insulation layers or sheaths for special wires and cables.

Electrical & Electronics

Connectors & Sockets: For high-temp, high-frequency, and precision parts like IC test sockets.

Coil Bobbins & Insulators: Used in high-temp or high-voltage environments.

FPC Substrates: TPI film as coverlay or substrate for high-temp flexible circuits.

Semiconductor Manufacturing: For wafer handling, testing, and packaging parts needing high-temp, low outgassing, and plasma resistance.

Industrial Machinery

Bearings & Bushings: For sliding parts in harsh, high-temp, and corrosive conditions with low friction and high wear resistance.

Pump & Valve Parts: For corrosion and high-temp resistant components in chemical, oil, and gas industries.

Compressor Components: Piston and guide rings for oil-free or high-temp operations.

Wear Parts: For wear strips, guide rails, gears, and other equipment components.

Automotive Industry

Engine & Transmission Systems: Used to manufacture high-temperature, wear-resistant components like thrust washers, seal rings, and bearing cages.

Electrical Systems: Applied in sensor housings, connectors, etc., requiring high-temperature resistance.

Dalian Allstar Material Co., Ltd.

Your Trusted Thermoplastic Polyimide TPI Supplier & Solution Provider

Dalian Allstar Material, China—offering high-quality Thermoplastic Polyimide (TPI) products and wholesale solutions.

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