Beyond High-Temperature Nylons: Performance & Applications of 5 Heat-Resistant Engineering Plastics

I. PPO (Polyphenylene Oxide)  

A top-five global engineering plastic, PPO offers high rigidity, thermal stability, flame resistance, strength, and electrical properties. It also features wear resistance, non-toxicity, and stain resistance. With the lowest dielectric constant/loss among engineering plastics (unaffected by temperature/humidity), it suits low-to-high-frequency electric fields.  

Combustion Characteristics  

Self-extinguishing; dense black smoke with floral/fruity odor during melting.  

Key Advantages  

- Highest Tg (210°C) among thermoplastics  

- Withstands boiling water without deformation  

- Superior creep resistance vs. PA/POM/PC; high surface hardness  

- Maintains ductility at -135°C; exceptional dimensional stability  

- Stable dielectric properties across frequency/temperature/humidity ranges  

- Supports metallization (electroplating/vacuum deposition)  

Limitations  

Stress cracking with solvents; poor UV resistance; low melt flow.  

Applications  

Moisture-loaded environments requiring dielectric/mechanical performance:  

- Microwave insulators  

- Water treatment equipment  

- Medical devices  

- Food-contact components  

- High-stiffness electrical housings  

Processing Notes  

- Melting point: 217°C | Decomposition: 360°C  

- Processing temp: 280–340°C  

- Drying: 140°C × 2–4 hrs (hygroscopic)  

II. PPS (Polyphenylene Sulfide)  

White crystalline polymer with extreme thermal stability and thermoset-like durability.  

Combustion Characteristics  

Non-flammable; self-extinguishing; metallic "clinking" sound when struck.  

Key Advantages  

- Solvent resistance at elevated temperatures  

- Outstanding creep/mechanical properties  

- Stable dimensions/performance under heat  

- Consistent dielectric properties  

Limitations  

Low impact strength; brittle fracture tendency.  

Applications  

High-temperature/humidity/load environments:  

- Electrical insulation  

- Corrosion-resistant chemical equipment  

Processing Notes  

- Melting point: 280°C | Decomposition: 400°C  

- Processing temp: 300–340°C  

- Drying: 140°C × 2–4 hrs  

III. PSF (Polysulfone)  

Amber-translucent or ivory-opaque polymer (density: 1.24 g/cm³).  

Combustion Characteristics  

Self-extinguishing; yellow-brown smoke; rubbery burning odor.  

Key Advantages  

- Retains 80% strength at 150°C; 75% at -100°C  

- Excellent creep resistance  

- Stable dielectric properties at 190°C (even wet)  

- Radiation resistance  

- Metallization capability  

Limitations  

Hydrolytic stress cracking under load; low melt flow.  

Applications  

- Precision connectors/relays (dimensional stability)  

- Chemical/thermal exposure components  

- Water treatment parts (pumps/valves)  

Processing Notes  

- Processing temp: 280–320°C  

- Drying reference: PC standards  

IV. Polyarylate (e.g., U-100)  

Combustion Characteristics  

Self-extinguishing; low smoke density (non-toxic).  

Key Advantages  

- Inherent heat resistance (no glass fiber needed)  

- Self-extinguishing without halogen additives  

- Low CTE, creep, and moisture absorption  

- Acid/oil resistance  

Limitations  

Degrades with alkalis/organic solvents.  

Applications  

Household appliances:  

- Heat-resistant components  

- Insulating elements  

Processing Notes  

- Drying: 100–120°C × 4–6 hrs  

- Processing temp: 330–350°C  

V. Polyarylsulfone (e.g., Astrel 360)  

Transparent polymer with higher density than PSF.  

Key Advantages  

- 100°C higher HDT/continuous use temp vs. PSF  

- Retains mechanical strength at extreme heat  

Limitations  

Poor flow; high processing precision required.  

Applications  

Ultra-high-temperature scenarios:  

- Aerospace components  

- High-end electronic insulators  

Processing Notes  

- Processing temp: 320–410°C  

- Mold temp: 232–260°C  

- Drying: 260°C × 2–4 hrs  

Terminology Consistency:  

- Tg: Glass transition temperature  

- CTE: Coefficient of thermal expansion  

- HDT: Heat deflection temperature  

- Self-extinguishing: UL94 V0 compliance  

- Metallization: Electroplating/vacuum deposition capability  

- Hygroscopic: Material moisture absorption tendency