PEEK Polyetheretherketone

PEEK is a linear polyaromatic thermoplast having the following chemical structure  

It is a proprietary product of ICI and is an engineering polymer suitable for applications that require mechanical strength with the need to resist difficult thermal and chemical environments. PEEK has an operating temperature range of —85 to +480°E ( — 65 to +250°C). 

PEEK is not chemically attacked by water. It has excellent long-term resistance to water at both ambient and elevated temperatures. It also has excellent rain erosion resistance. Because PEEK is not hydrolyzed by water at elevated temperatures in a continuous cycle environment, the material may be steam sterilized using conventional sterilization equipment. 

PEEK is insoluble in all common solvents and has excellent resistance to a wide range of organic and inorganic solvents. 

It also exhibits excellent resistance to hard (gamma) radiation, absorbing over 1000 Mrads of radiation without suffering significant damage. 

Polyetheretherketones are high performance, semi-crystalline, melt processable materials with a imique combination of properties. 

PEEKS can be made by two general routes. In both cases the main difficulty is to keep the crystallisable polymer in solution. Formation of the carboxyl link by polyaroylation can be carried out in liquid HF by catalysts such as BF3. The reaction is also possible in solvents such as dichlorobenzene with an excess of AICI3 both to catalyse the reaction and to solubilise the polymer by complexing with the carbonyl group in the backbone. AICI3 must then be neutralized and extracted from the polymer. The waste stream contains organic compounds, aluminium salts and hydrochloric acid. 

The alternative is to form the ether link via displacement of activated halogen atoms by phenoxide anions. Hence PEEK can be manufactured from 4,4 -difluorobenzophenone and hydroquinone. The polymer is then isolated by removal of the alkali metal fluoride and the polymerisation solvent. 

A comparison of key performance properties for three different grades of PEEK polymers is summarised in Table 3.13. 

High temperature performance - a continuous service temperature of up to 260 °C (500 °F) with excellent electrical and mechanical properties retained Melt temperature of 343 °C 

Polyaryletherketones (PAEK) are aromatic polymers with ether and ketone linkages in the chain, viz., PEK, PEEK, PEEKK, etc. Polyetheretherketone (Victrex PEEK), [-(j)-C0-(t)-0-(t)-0-]n, was commercialized in 1980 (Tg = 143 °C, Tm = 334 °C). Commercial blends of PEEK include Sumiploy PEEK/PES/ PTFE, PEEK/LCP, Cortem PEEK/LTG, etc. Evolution of PEEK blends technology is outlined in Table 1.72. 

---

For fluorine-free products, the labiUty of fluorine in fluoronitrobenzenes and other activated molecules permits it to serve as a handle in hair-dye manufacturing operations, high performance polymers such as polyetheretherketone (PEEK), production of dmgs such as diuretics, and fiber-reactive dyes. Labile fluorine has also been used in analytical appHcations and biological diagnostic reagents. 

Another commercial appHcation of nucleophilic reactions of nitro-free duoroaromatics is the manufacture of polyetheretherketone (PEEK) high performance polymers from 4,4 -diduoroben2ophenone [345-92-6], and hydroquinone [121-31-9] (131) (see PoLYETHERS, AROMATIC). 

High-temperature TPs are available to compete with TSs, metals, ceramics, and other nonplastic materials. The heat-resistant TPs include polyetheretherketone (PEEK) and polyethersulfone (PES), polyamideimide, liquid crystal polymer (LCP) and others. 

Polyetheretherketone PEEK is a high-temperature, crystalline engineering TP used for high performance applications such as wire and cable for aerospace applications, military hardware, oil wells and nuclear plants. It holds up well under continuous 450°F (323° C) temperatures with up to 600°F (316° C) limited use. Fire resistance rating is UL 94 V-0 it resists abrasion and long-term mechanical loads. 

In the last decade, some systems, such as the Dionex DX-500, have been manufactured with a flow path using corrosion-resistant materials such as polyetheretherketone (PEEK , ICI Americas Wilmington, DE), rather than the traditional stainless steel. Since stainless steel is prone to corrosion by salts, particularly halides, the introduction of titanium, ceramic, and PEEK was welcomed by those performing chromatography in aqueous systems, particularly in biological applications. PEEK , however, is not useful in applications requiring pressures greater than about 4000 psi. 

Polyetheretherketone, PEEK High temperature polymers CH063O0.16 0.029 1.60 0.001 0.008 17.0... 

Polyetheretherketone (PEEK) fibers electrical properties of, 23 718 properties of, 20 199t sulfonation of, 23 717 PEEK-based composites, 26 764 Peel-apart color films, 19 286 Peel-apart film(s), 19 274, 281, 282, 299, 314... 

Polyether-foZoc/ -polyesther, 7 646 Polyether diols, 14 271 20 76 25 476 Polyetheretherketone (PEEK) fibers,... 

Fig. 6.9. Normalized fracture toughness, (Kc - AKQ)/K. of short glass fiber-thermoplastics injection molded composites as a function of reinforcing effectiveness parameter, ft (O) polyetheretherketone (PEEK) matrix (K = 6.5 MPa m) (A) polytetrafluoroethylene (PTFE) matrix (K = 1.9 MPaym).

The model PBZT/ABPBI molecular composite system is limited since the rod and the matrix do not possess glass transition temperatures for subsequent post form consolidation. In an effort to improve the processability for molecular composites, thermoplastics were used as the host matrix. Processing from acidic solvents requires the thermoplastic host to be soluble and stable in meth-anesulfonic add. Thermoplastic matrices were investigated including both amorphous and semicrystalline nylons [71,72], polyphenylquinoxaline (PPQ) [73] and polyetheretherketone (PEEK) [74], Table 5 shows the mechanical properties obtained for various processed PBZT thermoplastic molecular composite systems. As an example, the PBZT/Nylon systems showed 50-300% improvement over uniaxially aligned chopped fiber composite of comparable compositions. However, the thermally-induced phase separation during consol-... 

Engineering thermoplastics have also been used in preimpregnated constructions. The thermoplastic is thoroughly dispersed as a continuous phase in glass, other resins, carbon fibers (qv), or other reinforcement. Articles can be produced from these constructions using thermoforming techniques. For example, the aerospace industry uses polyetheretherketone (PEEK) in woven carbon-fiber tapes (26). Experimental uses of other composite constructions have been reported (27) (see also COMPOSITE MATERIALS, POLYMER-MATRIX). 

Another promising aspect of SME development has been directed toward achieving the continuous flow of an aqueous sample phase to a seemingly immobilized organic solvent drop, permitting the direct and continuous interaction of the drop with a fresh sample. The technique was called continuous-flow microextraction (CFME).11 12 In CFME, a polyetheretherketone (PEEK) tube is used as a holder for both the extraction solvent drop and the sample delivery supply. The drop (3 pL) is introduced into the PEEK tube via a valve and is pushed by the sample aliquot inside the tube until it reaches the tube outlet, where it remains (a little off-center of the tube) as a solvent drop. Then, the sample volume (typically 3 mL) is pumped continuously (from the PEEK tube) around the... 

---