PEEK (polyetheretherketone) polymers are carving out niches to replace metals in a variety of applications, particularly medical.
A semicrystalline thermoplastic with excellent mechanical and chemical resistance properties at high temperatures, PEEK is used to make bearings, piston parts, pumps, compressor plate valves and cable insulation. It's one of the few plastics compatible with ultra-high vacuum applications.
"This material greatly improves the lifespan of sealing elements in the valve," says Tim Bremner, vice president of materials technology at Hoerbiger Corp., explaining selection of PEEK for a new application. "There is a dramatic increase in overall reliability and high-temperature performance when compared to other commonly used valve plate materials."
New Series Targets Medical
A combination of mechanical properties and excellent resistances with biocompatibility are creating options for Vestakeep aromatic PEEK polymers in medical applications. A new medical series from Evonik is described as suitable for short-term body contact. The series includes a medium-viscosity grade, a high-viscosity compound and a powder grade. Engineers often specify PEEK as an inexpensive alternative to metals and other materials. PEEK is resistant to gamma rays or X-rays and offers X-ray transparency. Target applications include surgical instruments and endoscopes.
Machined Shapes are Implantable
Stock shapes made of Zeniva PEEK from Solvay Advanced Polymers offer a combination of broad chemical resistance, high strength, stiffness, excellent toughness and fatigue resistance. They are aimed at close tolerance machining of finished components and for prototypes used in injection molding applications. PEEK is one of four polymers that comprise the company's family of biomaterials being offered for use in implantable medical devices. They comply with ISO 13485 manufacturing and meet current Good Manufacturing Practices (GMP).
CFRP PEEK Makes a Tough Valve
Hoerbiger Corp., the world's largest independent compressor valve manufacturer, is using low-flow, carbon-fiber-reinforced PEEK compound to create a tough compressor valve plate with high thermal and dimensional stability. Tim Bremner, vice president of materials technology at the OEM, says, "Valve plate materials must provide a high degree of physical strength while maintaining high impact and cyclic fatigue resistance. In many instances, compressor plates compress highly acidic or caustic gas streams, posing serious challenges for the chemical compatibility of the valve plate material." The primary benefit of the PEEK compound from RTP Co. is the high flexural modulus achieved through careful incorporation of carbon fiber into the resin matrix during compounding.