Polyethersulfone (PES) - Complete Guide on High-temperature Engineering Polymer

Polyethersulfone (PES or PESU) is relatively a new class of polymer and known since 1972 when first introduced by ICI. This high-temperature engineering thermoplastic has good transparency and flame resistance, and it is one of the lowest smoke-emitting materials available.

Let’s explore key properties and benefits offered by PPS, in detail, which makes it a material of choice in several sectors. Get detailed technical information on PES by reviewing:

  » What is PESU – Polyethersulfone?
  » Key properties of PESU (physical, mechanical, chemical…)
  » How to optimize its properties?
  » What are the popular applications of PES
  » Different methods used to process PES

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What is PESU – Polyethersulfone?

Polyethersulfone (PES) - Complete Guide on High-temperature Engineering PolymerSulfone polymers or polysulfones (PSUs) is the class of high temperature thermoplastics which contains a common structural unit “diphenyl sulfone”. The polymers of this family (standard PSU, polyaryl sulfone, polyether sulfone, polyphenyl sulfone) are characterized by extraordinary, inherent flame retardancy and high transparency.

POLYETHERSULFONE – is one of the high-temperature engineering thermoplastics in the polysulfone family.

  • It is an amorphous, transparent thermoplastic. 
  • It is rigid, tough, and dimensionally stable over a wide temperature range. 

The low flammability and low smoke generation of PES make it a good candidate to meet FAA regulations for aircraft interior parts. Unreinforced grades are used in high-temperature electrical applications, bakery oven windows, and medical components. The reinforced grades are incorporated in radones, airplace components and automotive parts.

It can be processed on conventional injection molding, blow molding, extrusion and thermoforming equipment.

Some of the key producers of PESU include:

  » Solvay - Veradel®
  » BASF - Ultrason®
  » Lehmann & Voss - LUVOCOM®
  » RTP Company - RTP 1400 series

» View All Commercially Available PESU Grades & >20 Suppliers in Omnexus Plastics Database

This plastic database is available to all, free of charge. You can filter down your options by property (mechanical, electrical…), applications, conversion mode and many more dimensions.

Of all the polyarylsulfones (PSU, PESU, PPSU), PESU has the highest values of temperature resistance and tensile modulus in elasticity. PESU properties are similar to those of PSU, although it exhibits a higher impact strength and better chemical resistance. Its stiffness and stability are high, and its notch sensitivity is low.

Key Properties of Polyphenylene Sulfide (PES)

PES [CAS: 25667-42-9, Chemical name: Poly(oxy-1,4-phenylenesulfonyl-1,4-phenylene)] is produced through polysulfonation or polyester synthesis. It consists of mainly consists aromatic rings (phenyl and biphenyl groups) linked alternatively by ether and sulfone groups.

Molecular Structure of Polyethersulfone

Molecular Structure of Polyethersulfone
Molecular Formula: (C12H8O3S)n

  • An amorphous polymer which possesses bonds of high thermal and oxidative stability
  • Sulfone group provides high temperature performance
  • Ether linkage contributes toward practical processing by allowing mobility of the polymer chain when in the melt phase

Physical, Mechanical, Chemical Properties...

Polyether sulfone has a glass transition temperature news 225°C and is dimensionally stable over a wide temperature range. It has a heat-deflection temperature of 203°C at 264 psi. Certain grades are capable of operating at temperatures above 200°C.

  • It has outstanding long-term resistance to creep at temperatures up to 150°C.
  • It is superior to polysulfone, phenylene oxide-based resins, or polycarbonate in terms of creep.
  • It can be easily processed and exhibits low mold shrinkage.
  • It is also capable of being used continuously under load at temperatures of up to about 180°C and in some low-stress applications to 200°C. As constant stress of 3000 psi at 20°C for 3 years produces a strain of 1%, where as a stress of 6500 psi results only 2.6% over the same time period.

Polyethersulfone is especially resistant to acids, alkalis, oils, greases, and aliphatic hydrocarbons and alcohols. It is attacked by ketones, ester, and some halogenated and aromatic hydrocarbons.

  • The high-temperature oil and gas resistance allow Polyethersulfone to be used in automotive applications. 
  • The ability of PES to endure repeated sterilization allows it to be used in a variety of medical applications.

Check Out Several Other Properties (Electrical, Mechanical, Physical...) of PES with their values!

The polymer has:

  • Good optical clarity
  • Very good hydrolytic and sterilization resistance
  • Biocompatibility
  • Excellent insulation properties
  • Outstanding rigidity even at high temperatures

Limitation of PESU and How to Optimize its Properties?

  • Very high cost. Applicable for highly demanding applications 
  • Processing at high temperature and pressure 
  • Attacked by polar solvents such as ketones, chlorinated solvents and aromatic hydrocarbons 
  • Low resistance to UV light

Being amorphous in nature, PES furthermore suffers from a low stress crack resistance, especially during exposure to organic solvents. As discussed above, very high sales price is also among the major drawbacks of PES as compared to engineering thermoplastics like polyamides, polyesters and polycarbonates.

For this reason, the applications are rather limited and restricted to highly sophisticated small volume areas in the electronics, aerospace and medical industries.

However, blending of high performance PES with other engineering thermoplastics opens up an opportunity to improve processabilty as well as chemical properties of the base polymer. Depending on the amount of incorporated engg. thermoplastics, a significant price reduction of high performance PES might as well be achieved. These improvements accelerated the penetration into large volume applications.

  • The PES/PC blend leads to materials with good flow properties and have same mechanical performance as neat PES. Though due to amorphous nature of PC, there is no improvement in chemical resistance

  • PES/PA polymer alloys show improved flow, improved toughness and a stable morphology. Thanks to semi-crystalline nature of polyamides, the chemical resistance of these materials is significantly higher than the pure PES

Popular Application for PES High-heat Plastic

From aircraft interiors, automotive and electrical applications to medical and consumer uses, today PES has several market applications. Let’s discuss some of them in detail…

Polyethersulfone Replaces Metals/ Thermosets in Automotive

Automotive Applications of Polyethersulfone Polyethersulfone (PESU) has found growing usage in automotive applications. PESU resin reinforced with glass or carbon fibers is increasingly used in automotive components & thus replacing metal and thermoset materials.

Polyethersulfones are very high temperature resistant amorphous thermoplastics that are used where the performance requirements exceed the capabilities of other engineering plastics.

In the automotive industry, the main applications for PESU are found under-the-hood such as battery caps, oil pumps, oil control pistons, transmission parts, carburetor parts, bearing cages and ignition components. Polyethersulfone are also found in car headlights (screens, housings and reflectors).

Glass fiber-reinforced PESU is also particularly well suited to engine oil circulation systems because the polymer matrix ensures the necessary thermal and dimensional stability when in contact with hot engine oil.

» See All Glass Fiber-reinforced PESU Grades Now!

PESU's High Heat Resistance Performance for Electrical/Electronic Applications

High stiffness, strength and dimensional stability permit use of polyethersulfone in electrical/ electronics application.

Electrical/Electronic Applications of Polyethersulfone PESU is used in various electrical components such as coil formers; plug-and-socket connectors; injection-molded printed circuit boards; parts for power circuit breakers; parts for power contactors and relays; transparent covers for signal lamps and switchboards, lamp holders and lampshades; heat shields; sensors; chip carriers; chip trays; battery seals; TV components, hairdryer parts, oven, fan heater and projector components.

In the electrical/ electronic field, Polyethersulfone and polysulfone are subject to growing competitionfrom other less expensive amorphous high temperature plastics due to rising cost pressure.

» Search PESU Grades Based on Their Electrical Property

PESU for High Performance Industrial Applications

PES are majorly used where the performance required exceeds the capabilities of other engineering plastics such as polyamide. The exceptional property spectrum of these materials allows them to replace thermosets, metals and ceramics. Futhermore, PESU offers several benefits such as stiffness, mechanical strength, continuous operating temperatures etc.

In industrial markets, Polyethersulfone is used mainly for manufacture of pumps and valves for use in chemical and electrochemical industries, and in process equipment. In general, mechanical engineering, PES can be used in:

  • Oil level indicators
  • Parts for pumps and heat exchangers
  • Parts for automatic beverage dispensers and milking machines
  • Packing for absorption and distillation columns 
  • Seals and conveyor belt idlers

Outstanding Sterlization Resistance Make PES Suitable for Medical

PES withstands cold sterilants, disinfactans and germicides. It offers very high resistance to gamma and electron beam radiation over the entire range of service temperature. However, when exposed to high-energy radiation, it suffers a noticeable decrease in tensile strength at yield and a significant decrease in ultimate elongation.

PES parts can be repeatedly sterilized in superheated steam. After more than 100 sterlization cycle, it remans transparent and largely retain its high level of mechanical properties.

PES is widely used in medical applications such as membranes for dialyzers; instruments; parts for instruments; surgical theater luminaries; sterilizing boxes; infusion equipment; secretion bottles and reusable syringes.

Medical Applications of PES

Membranes Made from Polyethersulfone

Polyethersulfone (PES) is a very common polymer used in commercial membrane fabrication. The strong, microporous film asymmetric membranes are created from high-temperature polyethersulfone polymer. These membranes efficiently remove particulates from solutions during general filtration. Additionally, the low protein and drug binding characteristics maximize recovery of critical drugs used in I.V. therapy, chemotherapy and open-heart surgery.

Recently thin film composite membranes were successfully made using sulfonated polyethersulfone as a substrate material. These sulfonated polymers were found to match the performance of unmodified polyethersulfone (PES) polymer in RO applications. SPES is a modified PES in that there are sulfonic acid group located orthogonally to the ether on the aryl groups.

Thin Film Composite Membranes Made Using Sulfonated Polyethersulfone
Chemical structures of PES (L) and Sulfonated Polyethersulfone (SPES, R)
Source: University of Connecticut

Processing Methods and Conditions for Polyethersulfone

PES can be processed by conventional thermoplastics methods such as: injection molding, extrusion, blow molding or thermoforming. It exhibits low shrinkage. For injection molding, barrel temperatures of 340-380°C with melt temperatures of 360°C are recommended.

Mold temperatures should be in the range of 140-180°C. For thin-walled molding, higher temperatures may be required. Unfilled PES can be extruded into sheets, rods, films and profiles.

  • Processing temperature : 340 to 390°C
  • Drying is recommended, in order to obtain % of water < 0.04 %: 4 h at 150°C or 2h at 180°C.

Injection Molding

  • A mold temperature of 120-160°C is recommended. 
  • Screws of L/D around 25 are recommended. 
  • Polyethersulfone is suitable for injection of very small parts with tight dimensional tolerances due to its low lineic shrinkage.

Extrusion (film/sheet/tube)

  • Extrusion temperature : 340-390°C 
  • L/D around 20 is recommended 
  • Elasticity is generally high, so the orientation is weak.

Commercially Available PES (Polyethersulfone) Grades

Polyethersulfone is commercially available in blow molding, extrusion, and injection molding grades. Glass fiber-reinforced grades are available for increased physical properties.

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