PSU Polymer: Properties, Uses & Cost Guide
Tensile data verified against MatWeb.com database & manufacturer datasheets · Last updated July 2026
Published: 2026-06-02
Polysulfone (PSU) combines steam sterilizability (autoclave at 134°C, 1,000+ cycles), chemical resistance, and optical clarity in an amorphous, rigid thermoplastic. This unique combination makes PSU the dominant polymer for reusable medical...
Polysulfone (PSU) combines steam sterilizability (autoclave at 134°C, 1,000+ cycles), chemical resistance, and optical clarity in an amorphous, rigid thermoplastic. This unique combination makes PSU the dominant polymer for reusable medical devices and surgical instrument handles. Unlike semi-crystalline polymers that become opaque upon sterilization-induced crystallization, PSU remains transparent. FDA Master File: PSU is listed under 21 CFR 177.1655 for repeated food contact and has extensive ISO 10993 biocompatibility data supporting medical device applications.
PSU vs PPSU (Radel R): PPSU has higher impact strength and better chemical resistance but is amber-colored (not transparent). PSU is water-clear with a slight amber tint. Processing: PSU is hygroscopic — dry at 135°C for 4 hours. Melt temperature 330-380°C, mold temperature 120-160°C. High melt viscosity requires generous runners and gates. PSU is notch-sensitive — radius all internal corners to >0.5mm. Sterilization compatibility: EtO, gamma (yellowing), steam autoclave (1,000+ cycles), and hydrogen peroxide plasma (Sterrad).
Recommended Applications
PSU Polysulfone is commonly specified for:
Selection & Application Guide
Polysulfone (PSU) is a transparent, high-temperature amorphous polymer offering 150°C continuous service, excellent hydrolysis resistance, and autoclave capability at lower cost than PEEK or Ultem. Choose PSU when you need transparency with steam sterilization resistance — it fills the gap between polycarbonate (limited to 130°C, poor steam resistance) and Ultem (higher temperature but more expensive and amber-tinted). PSU is the standard for medical and food-service applications requiring repeated sterilization.
Real-World Applications
PSU withstands thousands of steam autoclave cycles at 134°C without degradation, making it standard for surgical instrument trays and dental cassette systems.
PSU's biocompatibility, transparency for visual inspection, and resistance to blood-contact sterilization make it the material for hemodialysis component housings.
PSU is FDA-compliant for repeated food contact and withstands commercial dishwashing temperatures — used for coffee machine components, hot water dispensers, and food processing sight glasses.
PSU's clarity, chemical resistance, and autoclave capability make it ideal for beakers, filter housings, and other lab ware that requires repeated sterilization.
Processing & Cost Considerations
Manufacturing Tips
- PSU processes at 360-390°C melt temperature with mold temperatures of 100-150°C. These temperatures are achievable on standard high-temperature injection molding machines — no special equipment required.
- PSU must be thoroughly dried before processing (120-130°C for 3-4 hours) as it is hygroscopic. Moisture causes splay marks and reduces mechanical properties.
- PSU has higher melt viscosity than polycarbonate — higher injection pressures and faster fill speeds are needed. Optimize gate design for adequate flow length, especially for thin-wall parts.
PSU costs $15-35/kg — less than Ultem ($30-80/kg) and significantly less than PEEK ($80-200/kg). This positions PSU as a cost-effective choice for transparent, sterilizable components. When opacity is acceptable and higher temperature is needed, Ultem may justify its higher cost. When transparency and autoclave resistance are the primary requirements, PSU is typically the most economical choice.
Technical Properties
| Density | 1.24 g/cm³ |
|---|---|
| Tensile Strength | 70 MPa |
| Melting Point | Amorphous (Tg 185°C) |
| Shrinkage Rate | 0.7% |
| Flexural Modulus | 2.7 GPa |
| Hdt | 174 °C at 1.82 MPa |
Engineering Tool: Shrinkage & Cost Estimator
Calculate part weight, mold cavity dimensions accounting for shrinkage, and material cost — all locally in your browser.
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| Udel P-1700 | |
| Ultrason S | |
| Radel R (PPSU) — higher impact variant |
Frequently Asked Questions
What is the difference between PSU, PPSU, and PES?
PSU (Udel, Ultrason S): transparent, rigid, Tg 185°C, lowest cost of the three. PPSU (Radel R, Ultrason P): amber-colored, highest impact strength, Tg 220°C, best chemical resistance. PES (Ultrason E, Veradel): transparent, Tg 225°C, highest thermal performance. Select PSU for transparency + autoclave; PPSU for impact + chemical; PES for highest thermal.
Can PSU be sterilized with gamma radiation?
Yes, but gamma causes yellowing — the color shift is cosmetic and does not affect mechanical properties. For medical devices where color is critical (light pipes, viewing windows), EtO or hydrogen peroxide plasma sterilization is preferred because they do not discolor PSU.
What is the difference between PSU, PES, and PPSU?
PSU (polysulfone, Udel) has 150°C continuous service, excellent clarity, and the lowest cost of the three. PES (polyethersulfone, Veradel/Ultrason) offers 180°C service and better chemical resistance at higher cost. PPSU (polyphenylsulfone, Radel) provides the highest impact toughness (notch sensitivity 10× better than PSU) and 180°C service. Choose PSU for standard sterilization, PES for higher temperature, PPSU for impact-critical medical applications.
Is PSU truly transparent?
Yes. PSU is water-clear transparent with a slight yellow tint, providing better clarity than Ultem (which is amber-tinted). PSU's light transmission is approximately 85-90% for 3mm thickness, suitable for sight glasses and inspection windows.
How many autoclave cycles can PSU withstand?
PSU typically withstands 1,000-2,000 autoclave cycles at 134°C before showing significant property degradation. This is far superior to polycarbonate (50-100 cycles) and comparable to Ultem. For applications requiring even more cycles, PPSU offers the best autoclave resistance among transparent polymers.
Can PSU be bonded or welded?
Yes. PSU can be solvent-bonded using methylene chloride or dichloroethane for strong, clear bonds. It can also be ultrasonically welded and heat-sealed. Solvent bonding is the most common joining method for medical device assembly.
Is PSU resistant to chlorine and chlorinated water?
PSU has good resistance to chlorinated water at moderate temperatures, making it suitable for pool and spa components and water treatment equipment. However, prolonged exposure to hot chlorinated water above 60°C can cause stress cracking. For continuous hot chlorinated water service, PPSU offers better resistance.
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References & Industry Standards
- ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
- UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
- MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
- ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org