Material guide
PSU, polysulfone
PSU, polysulfone. A transparent high temperature plastic that can be boiled, steam sterilized and run in the autoclave over and over again without losing its shape. It belongs where hygiene and sterilization govern the choice of material.
What it is
PSU, polysulfone, is an amorphous high temperature plastic that is often transparent and that withstands repeated sterilization better than most. It handles hot steam, autoclave and hot water time after time without deforming or breaking down, and keeps its strength and stiffness in the heat. The material also resists many chemicals and cleaning agents, which makes it a recurring choice in medical technology, laboratories and food handling. PSU sits in the premium segment, a step above everyday engineering plastics but below the very most expensive ones. It is available both as a pure grade and in filled versions, more about that under grades.
Properties
Withstands repeated sterilization in autoclave, steam and hot water without losing its shape
High continuous heat resistance compared with engineering plastics
Often transparent, you can see through it in suitable grades
Good resistance to many cleaning agents and disinfectants
Dimensionally stable and stiff even when hot
Glass fiber is available for higher stiffness and heat resistance
Common applications
PSU sits where things have to be sterilized time after time. Typical parts are components in medical technology equipment, instrument holders and parts that are run in the autoclave, plus membrane housings and vessels in water treatment and laboratories. It is also used in food environments where parts have to withstand hot cleaning, and in parts that need to be transparent and take heat at the same time. When a designer needs a material that survives hundreds of sterilization cycles without cracking or deforming, PSU is often the first stop.
Limitations
PSU is no everyday plastic in price, so it is chosen for its sterilization and heat properties, not as a cheap engineering plastic. It is sensitive to stress cracking in contact with certain solvents and greasy media, something to allow for in the design and the choice of material. UV and weather outdoors are not the material's home ground, so for prolonged outdoor use there are better choices. If your part needs higher chemical resistance, or even higher hot water resistance, PPSU or a fluoroplastic may suit better.
Our PSU grades withstand 160 °C in continuous operation and 180 °C for short periods, and go down to -40 °C.
Grades and variants
PSU is available in a pure grade and in filled versions. The grades differ in stiffness, heat resistance and whether the material is transparent or not.
Base grades
- PSU pure grade, often transparent. First choice for sterilizable and transparent parts.
Additives and reinforcements
- Glass fiber filled, for higher stiffness, heat resistance and dimensional stability, where the transparency has to give way.
If your part has to handle even harder sterilization cycles or higher impact strength, PPSU is a closely related alternative. We will help you compare.
Machining
PSU is sawn, milled, drilled and turned. The material cracks from certain solvents and greasy media, and the cracks often appear only after the part has been in place for a while, so check both the cutting fluid and the cleaning agent.
Formats we can supply
PSU is available as sheets, round rods and hollow bars. You see formats and dimensions in the range. Would you like a piece cut to size? Enter the dimensions in VisualCutter and you will see the price straight away.