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What Are Heat-Resistant Plastics? 6 Reliable High-Performance Engineering Plastics

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What Are Heat-Resistant Plastics? 

Key Thermal Properties of Heat-Resistant Plastics

Detailed Overview of 6 Heat-Resistant Plastics

>> 1. Polyetheretherketone (PEEK) Material

>> 2. Polyimide (PI) Material

>> 3. Polyphenylene Sulfide (PPS) Material

>> 4. Polyetherimide (PEI, trade name Ultem) Material

>> 5. Polyphenylsulfone (PPSU) Material

>> 6. Polysulfone (PSU) Material

What Are Heat-Resistant Plastics? 

Untill 2026, the common plastics with good heat-resistant properties include Polyetheretherketone (PEEK), Polyimide (PI), Polyphenylene Sulfide (PPS), Polyetherimide (PEI), Polyphenylsulfone (PPSU), and Polysulfone (PSU). Their long-term continuous operating temperatures span a wide range from 160°C to over 300°C: among them, PI leads the pack with a capability of 300°C+, followed by PEEK at 260°C, PPS at 220°C, PPSU at 180°C, PEI at 170°C, and PSU at 160°C. Leveraging their unique thermal properties, these materials are widely used in high-temperature applications across aerospace, automotive manufacturing, medical devices, and electrical and electronic industries.

Material
Long-Term Continuous Operating Temperature
Polyimide(PI)
300°C+
Polyetheretherketone(PEEK)
260°C
Polyphenylene Sulfide(PPS)
220°C
Polyphenylsulfone(PPSU)
180°C
Polyetherimide(PEI)
170°C
Polysulfone(PSU)
160°C

Key Thermal Properties of Heat-Resistant Plastics

When evaluating materials for high-temperature applications, the following five thermal metrics are the core indicators:
Performance Metric
Description
Glass Transition Temperature (Tg)
The critical temperature at which a material transitions from a rigid, glassy state to a flexible, rubbery state. For amorphous plastics, this is essentially the ceiling of their practical operating temperature.
Melting Point (Tm)
The specific temperature at which a semicrystalline plastic transitions from a solid to a liquid. Amorphous plastics and PI do not have a melting point; they only degrade at high temperatures without melting or dripping.
Heat Deflection Temperature (HDT)
The temperature at which a material deflects by a specified amount under a defined mechanical load (typically 1.8 MPa). This directly reflects the material's heat resistance under load-bearing conditions.
Continuous Operating Temperature
The maximum temperature at which a material can operate continuously over the long term without significant degradation of its key mechanical properties.
Decomposition Temperature (Td)
The temperature at which the molecular chains of a material begin to undergo chemical breakdown. A high decomposition temperature means a wider processing window and a higher safety margin.

Detailed Overview of 6 Heat-Resistant Plastics

1. Polyetheretherketone (PEEK) Material

PEEK Material is the benchmark among semicrystalline high-performance thermoplastics, combining extreme heat resistance, mechanical strength, and chemical inertness. Its long-term continuous operating temperature reaches 260°C, with short-term peak tolerance of 300°C. PEEK's decomposition temperature is as high as approximately 580°C, providing an extremely wide processing window. When reinforced with glass or carbon fibers, its Heat Deflection Temperature (HDT) can jump from 152°C to over 315°C, making it the material of choice for metal replacement in aerospace, medical implants, and semiconductor manufacturing.
Key Properties:
  • Glass Transition Temperature: 143°C / Melting Point: 341–343°C

  • Heat Deflection Temperature: 152°C (unreinforced, 1.8 MPa)

  • Continuous Operating Temperature: 260°C / Short-term: 300°C

  • Decomposition Temperature: ~580°C

  • Flame Rating: UL 94 V-0 (inherent)

Typical Applications: Aerospace brackets and interiors, medical implants, semiconductor wafer carriers, high-temperature automotive bearings, 3D printing high-performance filaments.

heat resistant plastic PEEK material

2. Polyimide (PI) Material

PI is one of the most heat-resistant engineering plastics. It is a thermosetting polymer with no melting point; at high temperatures, it only carbonizes without melting. Its long-term continuous operating temperature exceeds 300°C, with short-term tolerance of extreme temperatures up to 480°C. PI's Glass Transition Temperature ranges from 280–360°C, and it maintains excellent mechanical properties and electrical insulation at ultra-high temperatures, making it the ultimate material for military, aerospace, and deep-well exploration applications.
Key Properties:
  • Glass Transition Temperature: 280–360°C 

  • Heat Deflection Temperature: 280°C+

  • Continuous Operating Temperature: 300°C+ / Short-term Peak: 480°C

  • Decomposition Temperature: >500°C

Typical Applications: Aircraft engine components, flexible circuit board substrates, high-temperature sealing rings, deep-well drilling equipment, spacecraft thermal insulation layers.

heat resistance plastic PI material

3. Polyphenylene Sulfide (PPS) Material

PPS  Material is a semicrystalline specialty engineering plastic known for its exceptional chemical corrosion resistance and flame retardancy. Its long-term continuous operating temperature is 220°C, with a short-term peak of 260°C. The HDT of neat PPS is around 135°C, but with 30% glass fiber reinforcement, the HDT can jump to 250–260°C. It offers outstanding cost-effectiveness, making it a preferred choice for high-temperature structural parts in the automotive and industrial sectors.
Key Properties:
  • Glass Transition Temperature: 90°C / Melting Point: 280°C

  • Heat Deflection Temperature: 135°C (unreinforced, 1.8 MPa)

  • Continuous Operating Temperature: 220°C / Short-term Peak: 260°C

  • Decomposition Temperature: ≥500°C

Typical Applications: Automotive turbocharger piping, water pump impellers, electronic connectors, industrial filter bags, chemical pump and valve components.

heat resistant plastic PPS material

4. Polyetherimide (PEI, trade name Ultem) Material

PEI  Material is a high-performance amorphous thermoplastic that combines high strength with excellent dimensional stability. Its Glass Transition Temperature is as high as 217°C, but its long-term continuous operating temperature is rated at 170°C, with a short-term peak of 210°C. PEI is inherently flame retardant (UL 94 V-0), produces low smoke, and maintains good electrical properties at high temperatures, making it a common material for aircraft interiors and electronic enclosures.
Key Properties:
  • Glass Transition Temperature: 217°C 

  • Heat Deflection Temperature: 210°C

  • Continuous Operating Temperature: 170°C / Short-term: 210°C

  • Decomposition Temperature: ~500°C

Typical Applications: Aircraft interior panels, medical surgical instrument handles, 5G base station radomes, food processing equipment components, electrical insulation housings.

heat resistant plastic PEI material

5. Polyphenylsulfone (PPSU) Material

PPSU Material is the most heat-resistant amorphous plastic in the sulfone family, renowned for its exceptional resistance to repeated steam sterilization and impact toughness. Its Glass Transition Temperature is as high as 220°C, its long-term continuous operating temperature is 180°C, and its short-term peak can reach 230°C. PPSU is highly popular in medical and food-contact applications, capable of withstanding thousands of high-temperature, high-pressure sterilization cycles without aging.
Key Properties:
  • Glass Transition Temperature: 220°C / No melting point

  • Heat Deflection Temperature: 207°C

  • Continuous Operating Temperature: 180°C / Short-term Peak: 230°C

Typical Applications: Medical sterilization trays, dental instrument handles, baby bottles, airline catering utensils, hemodialysis equipment.

heat resistant plastic PPSU material

6. Polysulfone (PSU) Material

PSU is a classic high-performance amorphous plastic that offers good heat resistance, transparency, and electrical insulation. Its Glass Transition Temperature is 187°C, its long-term continuous operating temperature is 160°C, and its short-term peak is 190°C. PSU is moderately priced and easy to process, performing reliably in applications requiring both transparency and heat resistance.
Key Properties:
  • Glass Transition Temperature: 187°C

  • Heat Deflection Temperature: 174°C

  • Continuous Operating Temperature: 160°C / Short-term: 190°C

Typical Applications: PCB test fixtures, membrane modules for the food industry, medical dialyzer housings, lighting reflector covers, electrical switch bases.


Rio Liang | High-Performance Plastics Expert
 
Email: rioplastic@foxmail.com   TEL/Whatsapp/Wechat: 008613421811533
 
20+ Years specializing in PEEK, PPSU, PES, PPS & PEI materil modification. Expert in resolving material properties and injection molding solutions. Open to technical discussions.

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