Polyetheretherketone (PEEK) is a high performance, semicrystalline, high temperature resistant, engineering thermoplastic. It is one of the most popular materials we manufacture here at Craftech, with a strong following in the aerospace industry. In this article, we will describe some of the excellent mechanical properties that make this plastic material so popular.
The processing conditions used to mold PEEK can influence its crystallinity and mechanical properties. The Young's modulus is 3.6 GPa and its tensile strength is 90 to 100 Mpa. PEEK has a glass transition temperature of 143 °C (289 °F) and melts at 343 °C (662 °F.) With its resistance to hydrolysis, it is highly tolerant to thermal degradation as well as attacks by both organic and aqueous environments. It is susceptible to halogens and strong Bronsted and Lewis acids as well as some halogenated compounds and aliphatic hydrocarbons at high temperatures. It is soluble in concentrated sulfuric acid at room temperature. Some grades have a continuous operating temperature of up to 250 °C (482 °F). PEEK is highly resistant to thermal degradation as well as to both organic and aqueous environments. It is soluble in concentrated sulfuric acid at room temperature. PEEK has a UL flammability rating of V-0 and exhibits low smoke and toxic-gas emissions. It resists radiation and a wide range of solvents. PEEK can withstand boiling water and the superheated steam used with autoclave and sterilization equipment at temperatures higher than 482°F. The material also has superior creep resistance and is a high strength alternative to fluoropolymers
Several grades of PEEK are currently commercially available. The unfilled grade offers the highest elongation and toughness of all the grades of peek. It is available in light brown or tan and black. All unfilled PEEK grades comply with FDA regulation 21 CFR 177.2415 for food contact.
PEEK 30% glass filled includes glass fibers as an additive. It is ideal for structural applications that require improved strength, stiffness or stability at temperatures of about 300°F (150°). This grade dramatically lowers the material’s expansion rate and increases its flexural modulus. Glass-filled PEEK is light brown or tan in color.
PEEK 30% carbon filled uses carbon fibers as an additive. The carbon fibers enhance the compressive strength and stiffness of the material and dramatically lower its expansion rate. This plastic material grade offers optimum wear and resistance as well as excellent load carrying capability. Peek 30% carbon filled provides 3 ½ times higher thermal conductivity than unfilled peek, meaning that it dissipates heat from the bearing service faster. Peek 30% carbon filled is black in color.
PEEK (Bearing Grade, Ketron HPV™) is a grade that is reinforced with graphite, PTFE and carbon fibers. It offers the lowest coefficient of friction and the best machinability of all the PEEK grades. The PEEK bearing grade, Ketron HPV™ sports an excellent combination of low friction, low wear, high limiting PV, low mating part wear and easy machining. This grade is black or dark gray in color.
PEEK is often used in automobiles, the marine industry, the nuclear industry, oil-wells, electronics and aerospace industries. PEEK is considered an advanced biomaterial and is used in medical implants. It is also used increasingly in spinal fusion devices and reinforcing rods. Because of its robustness, PEEK is used to make items in demanding applications such as bearings, piston parts, pumps, compressor plate valves and cable insulation.
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