🧩 PSU – Polysulfone
(A transparent or semi-transparent technical material, rigid, with excellent temperature resistance (up to 160–180°C) and high dimensional stability. PSU is amorphous and chemically stable, used in precision parts and cooling systems.)
🔹 What is PSU
PSU (Polysulfone) is an amorphous thermoplastic polymer from the polysulfone family, alongside PES and PPSU. It is recognized for its thermal stability up to 180°C, its slightly yellowish (amber) transparency, and its excellent behavior under steam and thermal shock. Compared to PPSU, polysulfone is more rigid but has lower impact resistance. It excels in environments requiring resistance to oils, fuels, and detergents.
🔧 Composition & Properties
- Base: 100% Polysulfone.
- Density: 1.24–1.26 g/cm³.
- Vicat Softening Temperature: ≈ 190–200 °C.
- Chemical Resistance: Excellent.
- Continuous Heat Resistance: 160–180 °C.
🚗 Where PSU is used in the automotive industry
| Component | Example parts | Observations |
| Cooling Systems | Pumps, fittings, valves | Resists boiling fluids and steam |
| Electrical / Sensors | Covers, housings, connectors | Thermal and electrical stability |
| Braking / EGR | Control parts, valves | Rigid, zero shrinkage, easy to machine |
| Technical Interior | Transparent covers, frames | Glossy finish, amber color |
🔧 Welding Temperature and Methods
| Method | Optimal Temp | Observations |
| Hot Air | 320–340 °C | Slow melting, controlled airflow |
| Plastic Extrusion | 310–330 °C | Compatible with PSU or PES rods |
| Heat Plate (Mirror) | 310–330 °C | Clean bond, no oxidation |
🔩 Material Compatibility
- ✅ Compatible: PSU, PES, PPSU, PEI, PPS+PEI, PPS+PEEK.
- ⚠️ Good Compatibility: PPS, PPS+Noryl, PPA.
- ❌ Incompatible: PP, PE, ABS, PVC, PET, PC (completely different melting points).
💡 ReplastMD Recommendation: Use PSU or PES rods at 330°C. Heat gradually while maintaining a constant temperature to avoid internal bubbling. Slow cooling ensures a clear bond without internal stress.
🧠 How to Identify PSU
- Engraved marking: >PSU<, >UDEL<, >ULTRASON S<, >TECASON S<.
- Texture: Glossy or semi-transparent, very rigid.
- ReplastMD practical test: If the part is rigid, amber-colored, and does not deform under 250°C hot air, it is confirmed. Burns with a clean flame and a faint sulfone scent.
🛠️ PSU Welding at ReplastMD:
At our ReplastMD service center (Chisinau, Ciocana sector), we perform professional PSU / Udel welding for pump covers and thermal sensors, ensuring a clear, dense, and factory-grade finish.