PPSU / PEI / PSU

PPSU, PEI and PSU are high-quality plastics within the group of advanced engineering plastics. These materials are used when standard engineering plastics do not perform sufficiently in terms of temperature resistance, dimensional stability, strength, stiffness or resistance to moisture and steam.

The three plastics have many similarities, but differ in temperature resistance, toughness, chemical resistance and mechanical properties. That is why it is important to determine which material is most suitable for each specific application.

PPSU stands for polyphenylsulfone, PEI for polyetherimide and PSU for polysulfone. All three are amorphous high-performance plastics that are widely used for technical components in industries such as mechanical engineering, food processing, the medical sector and equipment manufacturing.

What are PPSU, PEI and PSU?

PPSU, polyphenylsulfone, is a high-quality plastic with high temperature resistance, excellent hydrolysis resistance and high toughness. PPSU is often selected for applications in which components are repeatedly cleaned or sterilised with steam.

PEI, polyetherimide, is a strong and rigid high-performance plastic with a high operating temperature and good dimensional stability. PEI also has good electrical insulating properties and is widely used in technical and electrotechnical components.

PSU, polysulfone, is a high-quality engineering plastic with a good combination of temperature resistance, mechanical strength, dimensional stability and hydrolysis resistance. PSU is often used in components where stability, toughness and reliability are important.

Key characteristics

• High maximum permissible operating temperature in air: 180 °C, 170 °C and 150 °C continuously for PPSU, PEI and PSU respectively
• High mechanical strength, stiffness and creep resistance, even at high temperatures
• Excellent hydrolysis resistance, suitable for repeated steam sterilisation
• High toughness, even at low temperatures
• Physiologically inert, suitable for contact with food
• Very high dimensional stability
• Translucent, non-optical quality, with the exception of PPSU, which is black
• Very good resistance to high-energy radiation, such as gamma rays and X-rays
• Good electrical insulating and dielectric properties

High temperature resistance

An important advantage of PPSU, PEI and PSU is their high temperature resistance. These materials retain their mechanical properties at elevated temperatures better than many standard engineering plastics.

Within this group, PPSU generally has the highest maximum permissible operating temperature in air, followed by PEI and PSU. This makes the materials suitable for applications in which components are exposed to heat for long periods or are regularly subjected to thermal loads.

For components that operate continuously in warm environments, this thermal stability is an important reason to choose PPSU, PEI or PSU.

Dimensional stability and mechanical stability

PPSU, PEI and PSU have high dimensional stability. This means that components retain their shape and dimensions well, even when they are loaded or exposed to fluctuating temperatures.

This property is important for technical parts where tolerances, fit and shape retention play a major role. Examples include housings, insulating components, guides, machine parts, precision parts and components that come into contact with heat, moisture or cleaning processes.

In addition, PPSU, PEI and PSU have good creep resistance. This makes the materials suitable for applications in which components are subjected to long-term mechanical loads.

Hydrolysis resistance and steam sterilisation

A distinctive property of PPSU, PEI and PSU is their good to excellent hydrolysis resistance. This makes these plastics suitable for applications involving moisture, hot water or steam.

PPSU in particular is known for its excellent resistance to repeated steam sterilisation. As a result, PPSU is widely used in medical, laboratory and food-related applications where cleanability and reliability are important.

PEI and PSU are also suitable for applications involving repeated cleaning, sterilisation or exposure to moisture, provided that the exact application and operating conditions are carefully assessed.

Electrical insulating properties

PPSU, PEI and PSU have good electrical insulating and dielectric properties. As a result, these materials are also used in electrotechnical and electronic components.

PEI is particularly often selected for technical components where dimensional stability, stiffness, temperature resistance and electrical insulation are all important. Examples include insulators, connector parts, housings and other components used in electrical or electronic applications.

Differences between PPSU, PEI and PSU

Although PPSU, PEI and PSU are similar, there are also clear differences:

PPSU is often selected when high toughness, hydrolysis resistance and resistance to repeated steam sterilisation are important. The material is suitable for demanding conditions in which components must continue to function reliably.

PEI is highly suitable when high stiffness, mechanical strength, dimensional stability and electrical insulation are required. PEI is often used in technical components that need to remain precise, strong and stable.

PSU offers a good balance between temperature resistance, toughness, dimensional stability and hydrolysis resistance. PSU is suitable for a wide range of technical applications where a high-quality plastic is required, but where the extreme properties of PPSU or PEI are not always necessary.

Machining PPSU, PEI and PSU at Lakwijk

PPSU, PEI and PSU are available as plastic semi-finished products, for example in sheet and rod form. At Lakwijk, we can cut these materials to size and further machine them into technical components.

Depending on the desired shape and application, PPSU, PEI and PSU can be milled, turned or processed in another way. For flat or rectangular parts, milling is often suitable. This allows features such as contours, recesses, drilled holes, tapped holes and bevelled edges to be added.

For round parts, such as bushes, rings, bearings or other cylindrical components, turning is often the most logical machining method.

We work based on the required dimensions, a technical drawing, a 3D model or a supplied sample. We also think along with you about the right material choice and machining method.