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Key Properties and Applications of PES

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. Explore key properties and benefits offered by PPS, in detail, which makes it a material of choice in several sectors.


What is PESU – Polyethersulfone?

What is PESU – Polyethersulfone?

Sulfone 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.

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 PESU (physical, mechanical, chemical…)

Key properties of PESU (physical, mechanical, chemical…)

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 and 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.

The polymer also exhibits the below mentioned set of properties.

  • 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?

Limitation of PESU and How to Optimize its Properties?

Along with the excellent performance properties offered by PES, there are some key limitation worth noting. These include:
  • Very high cost - only 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

Different methods used to process PES

Different methods used to process PES

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.

Find Suitable Polyethersulphone (PESU) Grade

View a wide range of polyethersulphone (PESU) grades available in the market today, analyze technical data of each product, get technical assistance or request samples.

Key Applications



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1 Comments on "Polyethersulfone (PES) - Complete Guide on High-temperature Engineering Polymer"
Kushlani P Oct 24, 2023
Good content. Easy to understand as well I would like to know, value of the refractive index of PES (polyethersulfone)

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