PSU Udel: Polysulfone High-Clarity Medical & Food-Grade Polymer Properties
Published: 2026-05-28
Polysulfone (PSU), commercially known as Solvay Udel, is the foundational member of the sulfone polymer family—the original high-temperature amorphous thermoplastic that established the market for transparent, sterilizable engineering polymers....
Polysulfone (PSU), commercially known as Solvay Udel, is the foundational member of the sulfone polymer family—the original high-temperature amorphous thermoplastic that established the market for transparent, sterilizable engineering polymers. With a glass transition of 185°C and continuous service rating of 160°C, PSU offers the best price-to-performance ratio in the sulfone family, costing significantly less than PES (Tg 225°C) or PPSU (Tg 220°C) while still providing excellent hydrolytic stability, clarity, and biocompatibility.
PSU is the workhorse material for medical device manifolds (dialyzer housings, surgical instrument handles), hot-water plumbing fittings, reverse osmosis membrane supports, and food service equipment. It is naturally transparent (slight amber tint) and maintains clarity after 1000+ autoclave cycles. PSU is FDA-compliant for repeated food contact and meets USP Class VI and ISO 10993 biocompatibility standards for medical devices. The material processes at melt temperatures of 330-380°C with mold temperatures of 80-150°C—the higher end of the mold temperature range produces lower molded-in stress and better environmental stress crack resistance (ESCR). Drying at 135°C for 3-4 hours to <0.02% moisture is required.
Technical Properties
| Density | 1.24 g/cm³ |
|---|---|
| Tensile Strength | 75 MPa |
| Melting Point | N/A (Amorphous, Tg 185°C) |
| Shrinkage Rate | 0.6-0.7% |
| Flexural Modulus | 2.7 GPa |
| Hdt | 174 °C at 1.82 MPa |
| Continuous Service Temp | 160 °C |
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 |
|---|---|
| Solvay Udel PSU | |
| BASF Ultrason S | |
| Sumitomo SumikaExcel PSU |
Frequently Asked Questions
What is the environmental stress crack resistance (ESCR) limitation of PSU?
PSU has good chemical resistance to aqueous solutions, acids, and bases, but it is susceptible to environmental stress cracking (ESC) when exposed to polar organic solvents—particularly ketones (acetone, MEK), esters, chlorinated solvents (methylene chloride), and aromatic hydrocarbons. The cracking occurs when the chemical attacks the polymer while the part is under molded-in or applied stress. Mitigation: (1) anneal parts after molding (160°C for 2-4 hours) to relieve molded-in stresses, (2) avoid press-fit or interference-fit designs that create sustained tensile stress, (3) use radiused internal corners (minimum 0.5 mm radius) to reduce stress concentration factors. For applications involving repeated solvent exposure, upgrade to PPSU (Radel) which has significantly better ESCR.
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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