PPSU Printing – Temperatures, Requirements and Problems

PPSU (Polyphenylsulfone) is a durable, high-performance amorphous engineering thermoplastic commonly used in applications requiring high resistance to heat or chemicals. Due to the properties of PPSU, it is used in a wide range of products spanning from baby bottles through to aerospace components.

3D printing with PPSU is possible, and can be purchased in filament, granule, or powder form, depending on which additive manufacturing system is being used. However, it should be noted that PPSU is quite tricky to print without the proper hardware and printing parameters, as is commonly the case with high-performance plastics with high temperature processing requirements.

Which is why we will dissect the difficulty of printing PPSU and how to get it right, and why one might choose PPSU as the material for their engineering needs.

Material Structure and Its Relevance to Printing

PPSU is a member of the polysulfone family of polymers.

The PPSU molecule consists of aromatic benzene rings connected by sulfone groups, along with ether linkages that connect the benzene rings into a polymer chain. The sulfone group is strongly electronegative and restricts rotation of the aromatic rings around it, and that rigidity is what puts PPSU’s glass transition temperature at 220–230 °C. Every processing temperature in the table below follows from that one number.

The amorphous nature of PPSU means that its chains never pack into an ordered crystalline phase. Thus, PPSU has no melting point, softening progressively above Tg instead. The relevance to printing is that nothing changes state as the part cools. The chains simply lose mobility gradually, finally solidifying, while the chains stay disordered tangles as they were in the melted state. This means the shrinkage comes from thermal contraction and post-print heat treatment will not affect the final result.

The above means that the high chamber temperature is not necessary for a crystallization process like PEEK printing needs, but rather for proper layer adhesion during the print.

PPSU Printing Temperatures

The table below shows required printing temperatures for an unfilled PPSU filament.

Description	Value
Printer nozzle temperature	380 – 400°C (minimum)
Heated bed temperature	180 – 200°C (minimum)
Chamber temperature	225°C (minimum)
Print Speed	18 mm/s
Bed Material	Garolite G-10 (preferred), CF PEEK, PEI, or PPSU
Bed Adhesion	Glue stick
Pre drying recommendations	150 – 170°C for a minimum of 4 hours

Printer Features

As shown in the table above, PPSU is not something that can be printed on a consumer-grade printer. The high temperatures needed across the board means that an industrial-grade additive manufacturing system is required to print the material reliably.

Nozzle

Firstly, the nozzle temperature required is roughly 1.5x that which can be supplied by consumer-grade machines. And being of such elevated temperatures, an all-metal hotend should be used rather than one with PTFE components inside. For the nozzle itself, a high temperature version capable of handling temperatures over 380 – 400°C is needed. Unfilled PPSU is not particularly abrasive, so a hardened steel nozzle is perfectly acceptable.

Printer Bed

In terms of print bed temperature, PPSU is fairly demanding in this regard, requiring bed temperatures almost twice that for common consumer-grade filaments. The required bed temperature of 180 – 200 °C is easily achievable for most industrial systems.

Chamber Temperature

While consumer-grade 3D printers can be modified to reach PPSU processing temperatures in terms of nozzle and bed temperatures, the extremely high chamber temperatures needed for PPSU printing require industrial 3D printing systems. PPSU has a very high glass transition temperature of 220–225 °C, and printing with a chamber temperature in that region is mandatory for high quality and repeatable prints.

Common Issues with PPSU Printing

As with many filaments, PPSU is prone to warping if the thermal environment isn’t up to requirements. While PPSU is an amorphous thermoplastic and is not susceptible to shrinkage-related warping like semi-crystalline plastics, it is still open to warping as it is extruded onto the build plate.

Due to the high extrusion temperature of PPSU, printing it onto a cooler bed results in a large thermal gradient, which in turn results in thermal contraction during cooling, residual stresses in the part, and ultimately, warping on the bed. This is why both the bed temperature and chamber temperature requirements are so high for PPSU.

Naturally, if the part warps, other defects can manifest in the part such as cracking, layer delamination, and general dimensional instabilities.

Print Speed

Another thing worth considering is the print speed, which is listed as being around 18mm/s. This need for a low printing speed is also related to PPSU’s high nozzle temperature requirements. In short, printing with a lower speed means that there is a lower volumetric flow from the nozzle, meaning that the material can be heated more efficiently as it is being deposited. A hotter deposited material means that better interlayer diffusion occurs, resulting in a stronger part. The obvious downside is that the print takes longer to finish.

Of course, it is likely quite possible to print at higher speeds, however, this low speed is suggested by manufacturers to ensure consistency and quality of the printing process. If you are printing with PPSU and notice under extrusion, void formation, or poor layer bonding, checking the print speed might be a good place to start when trying to pinpoint the diagnosis.

On the topic of layer bonding, PPSU is known for its toughness and strong layer bonding, and as a consequence, removal of support material can be a little tricky, particularly if PPSU is also used as a breakaway support. For best results, a soluble support material should be used where possible.

Moisture

Finally, regarding the topic of water absorption, PPSU is not especially hygroscopic when compared to materials such as nylon, measuring just 0.37% water uptake over 24 hours. However, given the elevated printing temperatures of PPSU, even a tiny bit of moisture can cause problems during extrusion, so follow the manufacturer’s recommendations regarding drying of materials.

PPSU Applications

Sector	Why PPSU?	Typical printed parts
Aerospace	High heat and chemical resistance, toughness, dimensional stability and flame-retardant capability (UL 94 rated for some blends) make PPSU suitable for demanding aerospace environments.	Aircraft cabin components, functional prototypes and production parts requiring heat/chemical resistance and low flammability.
Automotive	PPSU provides high thermal stability, chemical resistance and mechanical toughness, making it suitable for components exposed to heat, oils, fuels and other aggressive automotive environments.	Engine-emissions components, functional prototypes and production parts exposed to elevated temperatures and chemicals.
Medical / Healthcare	PPSU combines toughness, chemical resistance, high-temperature performance and resistance to repeated sterilisation by steam,plasma and radiation.	Sterilizable medical components, functional prototypes and production parts requiring repeated exposure to sterilisation processes.
Fluid Handling / Plumbing	PPSU has excellent hydrolysis resistance, chemical resistance and temperature capability, while its toughness makes it suitable for demanding fluid environments.	Fluid-handling components, plumbing components and complex pressure-containing geometries.
Industrial Manufacturing	High heat resistance, chemical resistance, toughness and dimensional stability allow PPSU to be used where conventional engineering thermoplastics cannot tolerate the operating environment.	Manufacturing tooling, tooling aids, functional prototypes and limited-production parts exposed to heat and industrial chemicals/lubricants.

When to Choose PPSU Over Other Plastics?

Given the difficulty in printing PPSU regarding high temperatures, and the capital required to invest in the industrial grade printer needed for the task (and the cost of filament itself), it is hardly surprising that PPSU is quite niche in its appeal in terms of accessibility.

But beyond the costs and difficulty, in what event would one choose PPSU over other high performance engineering plastics?

Well, like other premium thermoplastic feedstocks, PPSU is not valued for a single material parameter in isolation, rather it is preferred when a very select combination of material properties is needed. In particular, PPSU is prized for its high heat and chemical resistance, as well as its toughness. But there are other plastics (particularly engineering plastics like PEI or PEEK) that also satisfy such requirements. So when is PPSU the right choice to make?

First, let’s compare PPSU to common consumer-grade filaments, because the choice is much clearer to see when examined in this context.

Common plastics such as ABS, PETG, or PLA, all have incredibly low HDT (heat deflection temperature) values, all in the sub-100°C region. PPSU in contrast has a HDT of over 200°C, measured at 1.8 MPa according to ASTM D648. So if you are in need of a plastic structure that can sustain loads at elevated temperatures, these common plastics don’t even compete.

So why opt for PPSU over other engineering-grade super plastics such as PEEK or PEI?

In short, when comparing PPSU to PEEK, PPSU offers better dimensional stability, as it is an amorphous plastic and doesn’t suffer from crystallization-related shrinkage. PPSU can be 2x cheaper than PEEK, and slightly easier to process.

When compared to PEI, the differences are even less apparent, as both PEI and PPSU are amorphous. But in this comparison, PPSU ranks higher in terms of chemical resistance, resistance to hydrolysis/steam, and improved impact resistance / toughness.

Ultimately, PPSU occupies a useful sweet spot where high-temperature performance, chemical resistance, hydrolysis/steam resistance, and toughness are required, without the crystallization-related processing demands of PEEK, or the comparatively lower toughness and hydrolysis resistance of PEI.

Where PPSU Actually Fits

PPSU asks for most of the same hardware PEEK does. The 380–400 °C hot end, the actively heated chamber, and the 180–200 °C bed are all necessities. Missing any of them results in deformations, delamination or poor layer adhesion, so the parts that should be performing to the numbers in the datasheet are failing at surprising points.

However, meeting the requirements returns all that PPSU has to offer, including steam and hydrolysis resistance, toughness well below freezing, and a filament at roughly half of PEEK’s price.