PSU · grade
PSU Unfilled
Properties of the Unfilled condition, compared with the other PSU grades.
Standard injection/extrusion grade: pick for transparency, autoclavability and general high-temperature insulating parts.
What is PSU Unfilled?
PSU Unfilled is PSU in the Unfilled grade — standard injection/extrusion grade: pick for transparency, autoclavability and general high-temperature insulating parts. PSU Unfilled has a yield strength of 70 MPa (10.2 ksi) and a tensile strength of 71 MPa (10.3 ksi) — stronger than 77% of polymer grades. Elongation at break is 60% and the elastic modulus is 2.5 GPa (0.363 Msi). PSU Unfilled has a density of 1.24 g/cm³ (0.0448 lb/in³), heavier than 63% of polymer grades. Its glass-transition temperature is 185°C (365 °F). Medical Grade is the default condition FabDigit quotes; Unfilled is available on request or by drawing note.
Advantages
- High service temperature — 150°C (302 °F), better than 78% of polymer grades
- Polishes to a fine finish — 70/100, better than 78% of polymer grades
- High strength — 70 MPa (10.2 ksi), better than 77% of polymer grades
- Conducts heat well — 0.26 W/m·K (0.15 BTU/hr·ft·°F), better than 76% of polymer grades
Limitations
- High embodied carbon — 7 kg CO₂/kg, worse than 77% of polymer grades
PSU Unfilled properties
Typical room-temperature values for PSU Unfilled — 13 properties are specific to this condition; the rest are grade-level values shared by every PSU grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical6
PSU Unfilled has a density of 1.24 g/cm³ (0.0448 lb/in³), heavier than 63% of polymer grades. Its glass-transition temperature is 185°C (365 °F).
Mechanical15
PSU Unfilled has a yield strength of 70 MPa (10.2 ksi) and a tensile strength of 71 MPa (10.3 ksi) — stronger than 77% of polymer grades. Elongation at break is 60% and the elastic modulus is 2.5 GPa (0.363 Msi).
Thermal11
PSU Unfilled is rated for continuous service to 150°C (302 °F). It conducts heat at 0.26 W/m·K (0.15 BTU/hr·ft·°F), better than 76% of polymer grades. Thermal expansion is 56 µm/m·K (31.1 µin/in·°F).
Electrical7
PSU Unfilled is an electrical insulator with a dielectric strength of 17 kV/mm (431.8 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (80/100), worse than 55% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of PSU Unfilled takes about 130 MJ of energy and emits 7 kg of CO₂ — more than 78% of polymer grades. Typical recycled content is 0%.
Manufacturability8
PSU Unfilled's machinability is good (65/100, better than 66% of polymer grades); weldability good (60/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other PSU grades and fills
PSU is also supplied in 8 other conditions. The full side-by-side table is on the PSU overview.
- Medical GradeDefaultChoose for reusable surgical trays, sterilization cases and fluid-handling devices needing biocompatibility documentation and 1000+ steam cycles.70 MPa tensile
- CF30Polysulfone compounded with 30% short carbon fiber for maximum stiffness, dimensional stability and static-dissipative behaviour at up to ~160 °C.155 MPa tensile
- GF40Highly filled 40% short-glass polysulfone for maximum stiffness, creep resistance and low thermal expansion in electrically insulating structural parts.130 MPa tensile
- GF30Highest stiffness/creep resistance and lowest CTE of the PSU family; opaque, more abrasive to tools and molds.117 MPa tensile
- GF20Mid-level stiffening with lower warpage than GF30; use for load-bearing housings at 120–150 °C.100 MPa tensile
- UnfilledStandard injection/extrusion grade: pick for transparency, autoclavability and general high-temperature insulating parts.71 MPa tensile
- EXT-STOCKPick when parts are machined from semi-finished stock; annealed shapes minimize stress crazing and post-machining distortion.70 MPa tensile
- PTFE-LUBUse for sliding/wear parts needing low friction at high temperature; strength and ductility drop versus natural PSU.55 MPa tensile
Working with PSU Unfilled
Is PSU easy to machine?
Machines like a tough amorphous plastic: sharp positive-rake carbide tools, high speed, light feed, air or water-soluble coolant only (avoid ketone/chlorinated cutting fluids); anneal blanks ~165 °C to relieve stress and prevent crazing.
Can PSU be welded?
Joins well by ultrasonic, hot-plate/hot-gas and spin welding; solvent bonding with methylene chloride blends is fast but leaves stress-crack risk, so epoxy or ultrasonic is preferred for medical parts.
Can PSU be formed, bent or molded?
Dry resin 3–4 h at 135–150 °C to <0.05% moisture, mold at 330–385 °C melt with 100–160 °C tool, moderate-high injection pressure; thermoformable and extrudable, shrinkage ~0.6% natural / ~0.2% GF30.
What surface finishes work on PSU?
Transparent grade can be flame- or vapor-polished and buffed to optical clarity; paints/adhesives need degreasing or plasma/corona activation; can be metallized or vacuum-sputtered, but unprotected surfaces yellow in sunlight.
PSU chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| bisphenol A (BPA) monomer unitpolycondensation with DCDPS forms the polysulfone backbone | ≈ 45 | 45 |
| 4,4'-dichlorodiphenyl sulfone (DCDPS) moaryl-ether-sulfone repeat unit -[O-C6H4-C(CH3)2-C6H4-O-C6H4-SO2-C6H4]- | ≈ 55 | 55 |
| glass fiberonly in GF variants (sized chopped E-glass) | 10 – 30 | 30 |
| PTFEonly in lubricated bearing grades | 10 – 15 | 15 |
| polysulfone polymernatural grade is 100% polymer; no filler, minimal additives | balance | — |
PSU Unfilled — frequently asked
What is PSU Unfilled used for?
PSU Unfilled is typically used for medical instrument trays and sterilization cases, dialyzer housings and membranes, food-contact containers, hot-water pipe fittings, electrical insulating components and reusable autoclavable medical parts. In short: high-heat steam resistant.
What is the yield strength of PSU Unfilled?
PSU Unfilled has a typical yield strength of 70 MPa (10.2 ksi) and a tensile strength of 71 MPa (10.3 ksi) — stronger than 77% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is PSU Unfilled easy to machine?
Reasonably — machinability is rated good (65/100, better than 66% of polymer grades). Machines like a tough amorphous plastic: sharp positive-rake carbide tools, high speed, light feed, air or water-soluble coolant only (avoid ketone/chlorinated cutting fluids); anneal blanks ~165 °C to relieve stress and prevent crazing.
Can PSU Unfilled be welded?
Yes — weldability is rated good (60/100). Joins well by ultrasonic, hot-plate/hot-gas and spin welding; solvent bonding with methylene chloride blends is fast but leaves stress-crack risk, so epoxy or ultrasonic is preferred for medical parts.
What surface finishes work on PSU Unfilled?
Transparent grade can be flame- or vapor-polished and buffed to optical clarity; paints/adhesives need degreasing or plasma/corona activation; can be metallized or vacuum-sputtered, but unprotected surfaces yellow in sunlight.
Can PSU Unfilled be formed, bent or molded?
Dry resin 3–4 h at 135–150 °C to <0.05% moisture, mold at 330–385 °C melt with 100–160 °C tool, moderate-high injection pressure; thermoformable and extrudable, shrinkage ~0.6% natural / ~0.2% GF30.
What is the maximum service temperature of PSU Unfilled?
PSU Unfilled is rated for continuous use to about 150°C (302 °F), and briefly to 180°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in PSU Unfilled?
Yes — PSU Unfilled is available for CNC machining, sheet metal and injection molding with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Udel PSU Design Guide & P-1700 data sheet — Solvay Specialty Polymers (2021)
- TECASON S (PSU) stock shapes datasheet — Ensinger (2022)
- CAMPUS plastics data – polysulfone (PSU) grades — CWFG / CAMPUS consortium (2023)
- Engineered Materials Handbook Vol.2: Engineering Plastics — ASM International (1988)
- ISO 527-2 / ISO 75 / ASTM D638, D790, D256, D257 test methods — ISO / ASTM (2019)
- GB/T 13527 / ISO 10993-1 biological evaluation reference for medical PSU — SAC / ISO (2018)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.