PEEKs

PEEK can be processed on all conventional processing technologies and so this material is often used in demanding and niche high-temperature engineering plastic applications. It has been used in a wide variety of applications including chemical pumps, coffee machines and microchips. 

PEEK is also easy to machine and so is often used in industry for the production of high-precision plastic components in small batches. 

PEEK is difficult to bond with engineering adhesives due to its low surface energy and usually requires some form of surface treatment (e.g., plasma) to give a good bond (Table 2.7). 

Notes All shear strengths are given as guidelines only and may vary considerably depending on grade of plastic, fillers, surface finish, etc. 

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Engleman R Jr, Rouse P E, Peek H M and Biamonte V D 1970 Beta and gamma band systems of nitric oxide Los Aiamos Scientific Laboratory Report no LA-4364... 

Peek K, Stryer L, Glazer A N and Mathies R A 1989 Single-moleeule fluoresoenoe deteotion autoeorrelation eriterion and experimental realization with phyooerythrin Proc. Natl Acad. Sc/. USA 86 4087-91... 

Brynda E, Fllady V and Andrade J D 1990 Protein peeking in adsorbed layers studied by exeitation-energy transfer J. Colloid Interface Sc/. 139 374-80... 

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). 

Fig. 5. Interlaminar fracture toughness, for a number of thermosetting and thermoplastic composites (36,37). Open white bars represent glass-fiber composites shaded bars are for carbon fibers. The materials are A, polyester (unidirectional) B, vinyl ester (CSM = chopped strand mat) C, epoxy (R/BR1424) D, epoxy (T300/914) E, PPS F, PES and G, PEEK. To convert J/m to fdbf/in. multiply by 2100.

Polyarylether Ketones. The aromatic polyether ketones are tme thermoplastics. Although several are commercially available, two resins in particular, poly ether ether ketone [31694-16-3] (PEEK) from ICI and poly ether ketone ketone (PEKK) from Du Pont, have received most of the attention. PEEK was first synthesized in 1981 (20) and has been well studied it is the subject of numerous papers because of its potential use in high performance aircraft. Tough, semicrystalline PEEK is prepared by the condensation of bis(4-fiuorophenyl) ketone with the potassium salt of bis(4-hydroxyphenyl) ketone in a diaryl sulfone solvent, such as diphenyl sulfone. The choice of solvent is critical other solvents, such as Hquid HE, promote the reaction but lead to premature low molecular-weight crystals, which do not exhibit sufficient toughness (21). 

Another method that has great potential for the preparation of advanced prepregs and has been explored extensively requites fine powders. The reinforcing fibers are coated with fine particles of the resin and, when heated, the resin flows over the fiber. This method requites finely divided particles either in aqueous solution, in an inert volatile solvent, or as high dielectric material that can be charged and coated by electrostatic attraction to the fiber. Synthetic methods that make fine particles, similar to that described for PEEK (23), are needed. 

Engineering thermoplastics have also been used ia preimpregaated coastmctioas. The thermoplastic is thoroughly dispersed as a coatiauous phase ia glass, other resias, carboa fibers (qv), or other reinforcement. Articles can be produced from these constmctions usiag thermoforming techaiques. For example, the aerospace iadustry uses polyetheretherketoae (PEEK) ia wovea carboa-fiber tapes (26). Experimental uses of other composite coastmctioas have beea reported (27) (see also Composite materials, polymer-matrix). 

Polyetheretherketone Resin (PEEK). The resia was commercialized as Victrex PEEK by Imperial Chemical Industries, Ltd. (ICl) ia the late 1970s and by Amoco Chemicals Corp. ia the middle 1980s under the trade name Kadel. It is produced by both companies ia the United States. Kadel is beheved made by the displacement reaction of 4,4 -difluorodiphenyl ketone by the potassium salt of hydroquinone ... 

Other companies offering similar materials are Du Pont, BASE, and Hoechst-Celanese. PEEK is a difficult resia to manufacture because of batch procedures and iasolubiUty. 

The PEEK resia is gray, crystalline, and has excellent chemical resistance T is ca 185°C, and it melts at 288°C. The unfilled resia has an HPT of 165°C, which can be iacreased to near its melting poiat by incorporating glass filler. The resia is thermally stable, and maintains ductiUty for over one week after being heated to 320°C it can be kept for years at 200°C. Hydrolytic stabiUty is excellent. The resia is flame retardant, has low smoke emission, and can be processed at 340—400°C. Crystallinity is a function of mold temperature and can reach 30—35% at mold temperatures of 160°C. Recycled material can be safely processed. Properties are given ia Table 16. 

Property ASTM method Victrex PEEK resia Reiaforced Victrex PEEK 30% glass 30% carboa ... 

The PEEK resia is marketed as aeat or filled pellets for iajectioa mol ding, as powder for coatiags, or as preimpregaated fiber sheet and tapes. Apphcations iaclude parts that are exposed to high temperature, radiation, or aggressive chemical environments. Aerospace and military uses are prominent. At present, polyamideimide (PAl) resia and poly(arylene sulfides) are the main competitors for apphcations requiring service temperatures of 280°C. At lower temperatures, polyethersulfones, amorphous nylons, and polyetherimides (PEI) can be considered. 

Production of PEEK resia is less than 500 t/yr worldwide (106). Growth is expected to exceed 10%/yr. Because of chemical and manufacturiag constraints, the price, ca 55/kg for neat resia, is likely to remain high. 

R. B. Rigby, PTCTREXPofethersnfone (PES) and TTCTKENPolyetherethersulfone (PEEK), SPE-RETEC, Mississauga, Ontario, Canada, Oct. 17,... 

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