BASF 3D Ultrafuse PPSU Fused Filament is an unfilled polyphenylsulfone feedstock derived from the BASF Ultrason P 3010 polymer platform and supplied in 1.75 mm diameter on 750 g spools. The material is amorphous and transparent amber in its natural grade. Datasheet values generated according to ISO 1183-1, ISO 527-2, ISO 178, ISO 75-1/-2, and ISO 306/B50 list density at 1.29 g/cm³, tensile strength at 69 MPa, tensile modulus at 2.3 GPa, flexural strength at 91 MPa, flexural modulus at 2.2 GPa, heat deflection under 1.8 MPa at 207 °C, and Vicat softening at 212 °C. The glass transition of the PPSU matrix is near 220 °C. Published machine settings range from 360 °C to 390 °C nozzle temperature, 140 °C to 160 °C bed temperature, and 90 °C to 120 °C chamber temperature.

Ultrafuse PPSU is processed on fused filament fabrication equipment with an enclosed heated chamber and an all-metal hot end capable of continuous operation at 390 °C. The filament is not abrasive, so a hardened nozzle is not required, but PTFE-lined hot ends are unsuitable because PTFE degrades above 260 °C. The product differs from lower-temperature amorphous filaments such as ABS and PETG in that the chamber, bed, and nozzle must remain above the glass transition range during the entire build cycle; otherwise residual stress accumulates at the intralayer boundary.

What separates unfilled PPSU filament from polysulfone and polyetherimide feedstocks?

In comparison with typical unfilled polysulfone filament, Ultrafuse PPSU shifts the heat deflection boundary upward while retaining comparable tensile strength. The following matrix lists datasheet values used to separate the two sulfone feedstocks during material selection.

Against unfilled polyetherimide filament, PPSU accepts a lower tensile modulus in exchange for higher notched impact and better hydrolytic stability. PEI-grade filament datasheets commonly list tensile modulus near 3.0 GPa and HDT/A between 200 °C and 216 °C depending on supplier, whereas PPSU is specified for repeated steam sterilisation and wet chemical duty where some PEI grades can develop environmental stress cracking. Specific PEI values vary by grade and should be read from the supplier’s material datasheet; published data for this specific configuration is limited.

Before extrusion, spooled feedstock is dried at 120 °C for 4 h in a forced-air oven according to the supplier’s handling instructions. Residual moisture absorbed by the sulfone matrix is converted to steam at melt temperatures above 360 °C; the resulting gas phase produces splay, microvoids, and reduced interlayer fusion. After drying, filament is kept in a desiccant dry box or an actively dried hopper. Exposure to uncontrolled room air above 50 % relative humidity can restore sufficient surface moisture to produce visible splay within a single build, particularly on the first layer and on long unsupported spans. A dew point below -30 °C in the dry storage environment prevents significant moisture regain during spool changes.

Extrusion, bed, and chamber temperature boundaries for reliable layer fusion

When the build chamber is held below 90 °C, flat PPSU sections with span greater than 120 mm may lift from the build plate or develop intralayer cracks because the amorphous resin solidifies under residual stress. The heated build platform is maintained from 140 °C to 160 °C to delay solidification. Adhesion to glass requires a high-temperature adhesive or a polyetherimide-based film. A flat borosilicate glass or carbon-fiber-reinforced build plate is specified, and the part cooling fan remains off. Nozzle temperatures below 360 °C reduce interlayer diffusion, while temperatures above 390 °C lower melt viscosity enough to produce stringing, nozzle drool, and local degradation if dwell time is uncontrolled. The hot end must operate continuously at 390 °C without PTFE liner degradation; an all-metal hot end with a hardened drive gear and a heat-break-isolated cold zone is required. The nozzle thermistor must be calibrated with a reference thermocouple at the heater block to avoid setpoint drift above 5 °C.

Layer adhesion is controlled primarily by chamber temperature, extrusion speed, and raster pattern. At a chamber setpoint of 120 °C, a layer height of 0.15 mm, a line width of 0.4 mm, and a unidirectional raster, printed specimens frequently exhibit in-plane tensile values close to the supplier’s reported injection-moulded datasheet values; published data for this specific configuration is limited, and printed-part results depend on toolpath, infill density, moisture state, and annealing history. Annealing at 160 °C for 2 h reduces frozen-in stress but may produce dimensional change below 1 %. Critical features are therefore post-machined or drilled after annealing rather than printed to final geometry.

Because the sulfone backbone resists hydrolysis, PPSU is used in printed fluid manifolds, autoclave trays, and reusable device housings. Selected PPSU base resin grades are tested for cytotoxicity per ISO 10993-5 and irritation or sensitisation per ISO 10993-10; however, the filament itself is not an ISO 10993-certified finished device, and printed parts require biocompatibility validation under ISO 10993-1 for the intended contact category. For repeated food-contact use, resin compliance may be referenced to 21 CFR 177.2500, but printed surfaces must be sealed or polished because porosity and interlayer voids can harbour process residues.

When sterilisation and chemical exposure set the service envelope

In steam autoclave service, printed PPSU is evaluated at 134 °C saturated steam for repeated cycles; cycle life depends on wall thickness, infill density, and internal stress from the build. The material is selected over amorphous PETG where thermal stability above 120 °C is required, and over some PEI grades where repeated steam exposure can promote environmental stress cracking. It is not recommended for continuous immersion in ketones such as methyl ethyl ketone, chlorinated solvents such as dichloromethane, or N-methyl-2-pyrrolidone, which stress-crack or dissolve the amorphous sulfone phase. Compatibility with aliphatic hydrocarbons, alcohols, dilute acids, and many aqueous salt solutions is documented in supplier chemical resistance tables for the base resin; validation is required for mixed solvent streams at elevated temperature above 60 °C.

For instrument housings and aircraft interior brackets, the product is processed with a brim or raft to minimise corner lift; part orientation is set so that the lowest-strength interlaminar direction does not carry primary load. Where aerospace interior compliance is required, printed specimens are evaluated for 12 s vertical ignition under 14 CFR 25.853; results depend on wall thickness, surface finish, and infill. Solvent bonding with methylene chloride is not recommended because the solvent attacks the sulfone matrix; adhesive bonding with epoxy or polyurethane systems is preferred after surface abrasion. Printed PPSU parts should not be placed in continuous service above their UL 746B relative thermal index without creep-rupture evaluation, and parts used in pressure boundaries require hydrostatic testing per the relevant ASME or ISO pressure-vessel code because FFF layer fusion cannot be assumed equal to injection-moulded PPSU.