High Performance Polymers

Since inception, Foster Corporation has focused on the custom formulation and blending of performance materials for critical medical applications. Our range of precision, twin-screw compounding equipment makes Foster ideally suited for custom compounding of high performance thermoplastics, such as Polyetheretherketone (PEEK), Polyetherimide (PEI) and Polyphenylsulfone (PPSU).

High Performance PolymersPolyetheretherketone 

Polyetheretherketone (PEEK) is a semi-crystalline thermoplastic that offers a unique combination of properties including high temperature performance, chemical, hydrolysis and wear resistance, electrical performance, and mechanical properties. The composition and inherent purity result in low levels of ionic extractables, low outgassing, and extremely low smoke and toxic gas emissions. PEEK is highly stable and requires no flame retardant additives to achieve a V-0 rating at 1.45 mm (0.057 in) thickness.

Key Properties of PEEK:

  • Maintains properties when exposed to a wide range of temperatures.
  • Excellent strength, stiffness, long-term creep and fatigue properties.
  • High abrasion and cut through resistance combined with low coefficient of friction.
  • Resistant to a wide range of chemicals at elevated temperatures in harsh environments.
  • Low moisture absorption, resistant to stream, water and brine, with low permeability.
  • Naturally flame retardant with electrical properties which are maintained over a wide frequency and temperature range.
  • Inherently pure with low particle generation and low outgassing for reduced contamination.


Polyetherimide (PEI) is an amorphous thermoplastic that offers outstanding elevated thermal resistance, high strength and stiffness, and broad chemical resistance. PEI is among the most dimensionally stable thermoplastics available, offering predictability over a wide temperature range. Filled grades offer exceptionally high-tolerance dimensional capabilities. Unlike most other amorphous thermoplastics, PEI resins retain strength and resist stress cracking when exposed to aliphatic hydrocarbons, alcohols, acids, and weak aqueous solutions.  Most grades of PEI are inherently flame resistant without additives, exceptionally difficult to ignite, and generate extremely low smoke.

Key Properties of PEI:

  • Excellent stability of physical and mechanical properties at elevated temperatures thanks to high glass transition temperature of 217 °C.
  • Outstanding strength and amorphous thermoplastic among the available alternatives, with predictable stiffness and strength up to 200 °C.
  • Exceptional dimensional stability over a wide temperature range.
  • Resistance to aliphatic hydrocarbons, alcohols, acids, and weak aqueous solutions
  • Limiting oxygen index (LOI) of 47%, meeting UL94 V0 specifications in sections as thin as 0.41 mm.
  • Low smoke generation per the NBS smoke evolution test


Polysulfone (PSU) is a transparent amorphous thermoplastic that offers higher heat resistance and better hydrolytic stability than polycarbonate (PC). It retains its good mechanical properties when exposed to steam and other sterilization techniques.  PSU excels in many fluid-handling applications and has successfully replaced brass in pressurized hot water applications. It exhibits low creep under a sustained load at elevated temperatures and can withstand continuous exposure to hot chlorinated water.

Key Properties of PSU

  • HDT of 174°C (345°F)
  • High strength
  • Good practical toughness
  • Excellent hydrolytic stability
  • Transparent
  • Colorable


Polyphenylsulfone (PPSU) is a transparent amorphous thermoplastic that offers the highest performance of the sulfone polymer family, with better impact resistance and chemical resistance than polysulfone (PSU) and polyetherimide (PEI).  The high heat resistance and excellent hydrolytic stability of PPSU make it an excellent choice for hot water fittings and medical devices requiring repeated steam sterilization.

Key Properties of PPSU

  • High HDT of 207°C (405°F)
  • Superior toughness and impact strength
  • Exceptional long-term hydrolytic stability
  • Better chemical resistance than PSU and PEI
  • Withstands over 1,000 cycles of steam sterilization without any significant loss of properties
  • Inherently flame retardant
  • Transparent
  • Colorable


Polyethersulfone (PESU) is a transparent amorphous thermoplastic that combines good chemical resistance with a high heat deflection temperature of 204°C (399°F). This resin is also inherently flame retardant.

Key Properties of PESU:

  • HDT of 204°C (399°F)
  • Good chemical resistance
  • Excellent electrical properties
  • Transparent