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Engineering Plastic

PSU (Polysulfone)

Polysulfone is an amorphous, transparent amber engineering thermoplastic rated to 160C continuous, with good toughness (60% elongation) and full chemical resistance. Its standout trait is repeated steam sterilizability, making it a staple for medical and fluid-handling parts that must survive autoclaving without losing strength or clarity.

How PSU (Polysulfone) machines

Rated 4.0/5 — PSU machines well with standard tooling, producing clean edges and good surface finish. The main caution is residual stress: aggressive cuts or built-up heat can trigger crazing, so use sharp tools, adequate coolant, and consider annealing stock before finishing tight-tolerance parts.

Manufacturing & processing

Offered in injection molding, CNC, and extrusion. Molding suits high-volume medical components; CNC from transparent stock makes prototypes and low-volume fluid parts. Being amorphous, it has predictable, low shrinkage and holds tight tolerances, which is why it is favored for sterilizable housings and manifolds.

Typical applications

Best for sterilizable medical devices and fluid handling — autoclavable trays, IV components, membrane housings, and labware. The amber transparency lets users see flow or fill levels. Its 160C rating and full chemical resistance also suit hot-water and food-contact fittings where repeated cleaning cycles are required.

When to choose it

Choose PSU when you need autoclavable, transparent, dimensionally stable parts and PPSU's higher cost or impact strength is not required. It machines easier than most high-temp plastics. Avoid it with ketones, chlorinated, and aromatic solvents, which cause stress cracking — switch to a fluoropolymer or PPSU in those environments.

Suitable surface finishes

Common finishes for PSU (Polysulfone): bead blasting, powder coating. Use the finish selector →

FAQ

Can polysulfone be autoclaved repeatedly?
Yes — repeated steam autoclaving is one of its defining strengths, which is why it is widely used for reusable medical and labware parts. It withstands many sterilization cycles at 134C without significant loss of strength or transparency, though PPSU tolerates even more cycles.
What solvents should I avoid with PSU?
Being amorphous, PSU is prone to stress-cracking from ketones, esters, chlorinated solvents, and some aromatics, especially under load. For service involving those chemicals, choose a semi-crystalline or fluoropolymer like PVDF or PPS instead, which resist solvent attack far better.
Why is polysulfone amber and transparent?
Its amorphous molecular structure transmits light, giving the characteristic clear amber color. This lets engineers monitor fluid flow, fill level, or particulates through housings and connectors — a practical advantage over opaque high-temp plastics in medical and fluid-handling assemblies.

Property values are typical/nominal for early guidance and vary by temper, grade, supplier and heat treatment. Confirm critical specs against a certified datasheet or with an mfgiq engineer.