Polyimides and Polyether Ketones

S Polyimides and Polyether Ketones Poly(ether imide), pel Applications electrical 

Poisson s ratio jjL Stress at yield Oy (MPa) Strain at yield Sy (%) Stress at 50% elongation aso (MPa) 0.41 5 

Notched impact strength (Charpy) (kJ/m ) Sound velocity Uj (m/s) Oongitudinal) Sound velocity Us (m/s) (transverse) 

Melt viscosity-molar-mass relation Viscosity-molar-mass relation 

Poly(ether ether ketone), PEEK. Applications injection-molded parts, automotive parts, aircraft parts, electronic parts, cable insulation, foils, fibers, tapes, plates. 

Poly (amide imide), PAI. Applications constructional parts, wheels, rotors, bearings, housings, slip fittings, lacquers. 

Poly(ether imide), PEI. Applications electrical housings, sockets, microwave parts, bearings, gear wheels, automotive parts. 

Polyimide, PI. Applications foils, semifinished goods, sintered parts. 

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Considerable attention has been devoted to the preparation of fluorine-containing polymers because of their unique properties and high temperature performance (I). Recently we reported the preparation and characterization of novel fluorine-containing polyimides and polyethers which exhibit low moisture absorption and low dielectric constants (2, 3). Fluorinated polyimides absorb 1 wt% water and have dielectric constants of about 2.8 (all dielectric constants reported in this paper were measured at 10 kHz) vtdiereas their non-fluorinated analogs absorb as much as 3 wt% water and have dielectric constants of about 3.2. Fluorinated polyarylethers, which are free of polar groups such as ketones, imides and sulfones, absorb as little as 0.1 wt% water and have dielectric constants less than 2.8. 

The primary resin of interest is epoxy. Carbon-fiber-epoxy composites represent about 90% of CFRP production. The attractions of epoxy resins are that they polymerize without the generation of condensation products that can cause porosity, they exhibit little volumetric shrinkage during cure which reduces internal stresses, and they are resistant to most chemical environments. Other matrix resins of interest for carbon fibers include the thermosetting phenolics, polyimides, and polybismaleimides, as well as high-temperature thermoplastics such as polyether ether ketone (PEEK), polyethersulfone (PES), and polyphenylene sulfide. 

Polymer Specimens. The materials used in this work were polyimide (PI),polyamide-imide (PAl), polyether-ether-ketone (PEEK), polyphenylene sulfide (PPS) and polyether sulphone (PES). The chemical formulas and physical properties of the specimen polymers are summarized in Table I. The specimen polymers, except PPS, were unfilled while the PPS specimen was filled with glass fiber of Uo wt. %. PAI and PES are amorphous polymer with considerably high glass temperature. The polymers, except PI, can flow at hi temperatures and allow the use of injection molding. 

Several reviews on membranes for DMFC fuel cells have been published in the last decade [1-9], starting with that by Kreuer [1], discussing the differences between Nafion and sulfonated polyether ketone membranes. According to Fig. 6.1, reviews published till 2006 [1 ] cover only one third of the ionomeric membranes currently developed for DAFC. More recent reviews deal with polyimide ionomer membranes [5], composite membranes for high temperature DMFC [6], non-perfluorated sulfonic acid membranes [7], modified Nafion membranes [8], and hybrid membranes [9-11]. 

In all three areas, some considerable success has been achieved in fulfilling the main objective, to the extent that, in some cases, adhesive formulations based on these three categories are at, or close to, full commercialization. For more detailed accounts of these developments, see the articles entitled Polyimide adhesives, Polyether ether ketone and Polyphenylquinoxalines. 

Cocondensation of macromers containing trialkoxysilyl groups with modified polystyrene (PS), polyoxazoline, polyimide, polyethylene glycol (PEG), polyether-ketones, polymethyl methacrylate, and derivatives of polytetramethylene oxide was established as convenient procedure for the preparation of telechelic polymer net-... 

The pol3miers given in this chapter are divided into polyolefines, vinyl polymers, fiuoropolymers, polyacrylics, polyacetals, polyamides, polyesters, polysulfones, polysulfides, polyimides, polyether ketones, cellulose, polyurethanes, and thermosets. The structural units of the polymers are as follows ... 

This survey covers measurements on plastics with all the reinforcing agents previously mentioned and includes a wide range of plastics now being used in plastics technology. It includes commonly used plastics such as polyamides, polyesters, polyethylene terephthalate, and epoxy resins, but also covers newer plastics, such as polyimides, polysulfones, polyethersulfone, polyphenylene sulfide, and polyether ether ketone, all of which have more specialized applications. 

Table A.31 Chemical resistance of polyimide (Pi), polyamide imide (PAI), polyphenylene ether (PPE). and polyether ether ketone (PEEK) sc = semi-crystalline [1039]...

Several materials have been studied on the goal of producing cost-effective PFMs [55-62]. Some of these are PBI-based membranes, polysterene membranes, sulfonated polyimide, cross-Unked poly(vinyl alcohol), and phosphobenzene, sulfonated poly(aryl ether ketone) —based manbranes. Sulfonation of aromatic thermoplastics such as polyether sulfone, polybenzimidazole, polyimides, and poly(ether ether ketone) makes them proton conductive suitable for fuel cell... 

In addition to Nafion-based catalyst layers, additional types have been developed, including CLs with different ion exchange capacities (lECs) [57,58] or with other hydrocarbon-type ionomers such as sulfonated poly(ether ether ketone) [58-60], sulfonated polysulfone [61,62], sulfonated polyether ionomers [63], and borosiloxane electrolytes [64], as well as sulfonated polyimide [65]. These nonfluorinated polymer materials have been targeted to reduce cost and/or increase operating temperature. Unfortunately, such CLs still encounter problems with low Pt utilization, flooding, and inferior performance compared wifh convenfional Nafion-based CLs. 

Different TPs have been used to modify thermosets, such as poly(ether sulfone) (PES), polysulfone (PSF), poly(ether ketone) (PEK), polyether imide (PEI), poly(phenylene oxide) (PPO), linear polyimides, polyhydan-toin, etc. (Stenzenberger et al., 1988 Pascal et al., 1990, 1995 Pascault and Williams, 2000). 

In recent years, remarkable progress has been made in the syntheses of aromatic and heterocyclic polymers to search a new type of radiation resistant polymers. Sasuga and his coworkers extensively investigated the radiation deterioration of various aromatic polymers at ambient temperature [55-57] and reported the order of radiation resistivity evaluated from the changes in tensile properties as follows polyimide > polyether ether ketone > polyamide > polyetherimide > polyarylate > polysulfone. 

A serious limitation to the use of organic polymers in general and of adhesives, in particular, is their poor resistance to thermal degradation. Considerable effort has been put into the development of High-temperature adhesives and examples of the materials that have been produced are described in articles on Polybenzimidazoles, Polyether ether ketone, Polyimide adhesives and Polyphenylquinoxalines. Some of the general principles used in the search for enhanced thermal stability are discussed in this article. 

Further discussion on the general theme of high-temperature adhesives can be found in the articles entitled Polyether ether ketones, Polyimide adhesives and Polyphenylqui-noxalines. 

In addition to conventional materials engineering polymers include materials as diverse as polyether ether ketone, polyimide, polyetherimide and polysulfides. 

The heat distortion temperature at 1.80 Mpa is the temperature that causes a beam loaded to 1.80 to deflect by 0.3 mm. If the heat distortion temperature is lower than the ambient temperature, -20 C is given. Polymers such as low-density polyethylene, styrene ethylene-butene terpolymer, ethylene-vinyl acetate copolymer, polyurethane, and plasticized polyvinyl chloride distort at temperatures below <50°C, whereas others, such as epoxies, polyether ether ketone, polydiallylphthalate, polydiallyl isophthalate, polycarbonate, alkyd resins, phenol formaldehyde, polymide 6,10 polyimide, poly-etherimides, polyphenylene sulfide, polyethersulfone, polysulfonates, and silicones, have remaikably high distortion temperatures in the range of 150°C to >300 C. Thermomechanical analysis has been used to determine the deflection temperature of polymers and sample loading forces (i.e., plots of temperature vs. flexure). 

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