Dimethyl PEEK

In partieular we specify on a new protocol for packing glassy polymer with intermediate eontrol of free volume distribution for four polyether-ether-ketones, an amorphous poly(oxa-p-phenylene-3,3-phthalido-/>-phenylenxoxa-p-phenyl-enexoxi-p-phenylene) (PEEK-WQ, the dimethyl PEEK-WC (DMPEEK), the tetramethyl PEEK-WC (TMPEEK) and the di-isopropyl dimethyl PEEK-WC (DIDMPEEK). 

Note that PEEK tubing has a lower pressure rating and might not be compatible with solvents such as dimethyl sulfoxide, tetra-hydrofuran, inorganic acids, and methylene chloride. 

Nylon, polyacetal, polycarbonates, poly(2,6-dimethyl)phenylene oxide (PPO), polyimides, polyphenylene sulfide (PPS), polyphenylene sulfones, polyaryl sulfones, polyalkylene phthalates, and polyarylether ketones (PEEK) are stiff high-melting polymers which are classified as engineering plastics. The formulas for the repeating units of some of these engineering plastics are shown in Figure 1.15. 

PC = polycarbonate PET = polyethylene terephthalate) PEEK = poly (aryl-ether-ether-ketone) PO = poly(oxy-1,4-pheny lene) PPS = poly (thio-l,4-phenylene) PPO = poly(oxy-2,6-dimethyl-l,4-phenylene) PEN = poly(ethylene-2,6-naphthalenedicarboxylate) PBT = poly... 

PB PBI PBMA PBO PBT(H) PBTP PC PCHMA PCTFE PDAP PDMS PE PEHD PELD PEMD PEC PEEK PEG PEI PEK PEN PEO PES PET PF PI PIB PMA PMMA PMI PMP POB POM PP PPE PPP PPPE PPQ PPS PPSU PS PSU PTFE PTMT PU PUR Poly(n.butylene) Poly(benzimidazole) Poly(n.butyl methacrylate) Poly(benzoxazole) Poly(benzthiazole) Poly(butylene glycol terephthalate) Polycarbonate Poly(cyclohexyl methacrylate) Poly(chloro-trifluoro ethylene) Poly(diallyl phthalate) Poly(dimethyl siloxane) Polyethylene High density polyethylene Low density polyethylene Medium density polyethylene Chlorinated polyethylene Poly-ether-ether ketone poly(ethylene glycol) Poly-ether-imide Poly-ether ketone Poly(ethylene-2,6-naphthalene dicarboxylate) Poly(ethylene oxide) Poly-ether sulfone Poly(ethylene terephthalate) Phenol formaldehyde resin Polyimide Polyisobutylene Poly(methyl acrylate) Poly(methyl methacrylate) Poly(methacryl imide) Poly(methylpentene) Poly(hydroxy-benzoate) Polyoxymethylene = polyacetal = polyformaldehyde Polypropylene Poly (2,6-dimethyl-l,4-phenylene ether) = Poly(phenylene oxide) Polyp araphenylene Poly(2,6-diphenyl-l,4-phenylene ether) Poly(phenyl quinoxaline) Polyphenylene sulfide, polysulfide Polyphenylene sulfone Polystyrene Polysulfone Poly(tetrafluoroethylene) Poly(tetramethylene terephthalate) Polyurethane Polyurethane rubber... 

The upper temperature at which polyelectrolytes can be utilised can be extended by substitution of a polar organic solvent for water in the electrolyte. Conductivities of up to 1 Q 1m 1 have been obtained for sulphonated PEEK using anhydrous pyrazole and imidazole at 200 C (Kreuer et al., 1998). Solvents used to form electrolytes in Nafion membranes have included alcohols, amines, propylene carbonate, dimethoxyethane, dimethyl form-amide, dimethyl sulphoxide and TV-methyl pyrrolidone. Typical conductivities for the latter three solvents are 10 to 1 O-lm 1 at room temperature, and the conductivity is thermally activated with activation energies in the range 9 to 24 kJ/mol (Doyle et al., 2001). 

In addition to the polymers described above, the MALDI technique has also been employed for the characterization of several synthetic polymeric materials. The literature reports the MALDI characterization of polyacrylonitrile (PAN), poly(ether sulfone) (PES), poly(dimethyl phenylene oxide) (PDMPO), and functionalized poly(p-phenylene)s. Analysis by MALDI-TOF of aromatic polyethers (such as PEEK), can be found, and several macrocyclic samples were also characterized by MALDI-TOF. ... 

In terms of polymer matrices for composite materials, there will be a compromise between solvent and water resistance. Thus non-polar resins are likely to be less resistant to hydrocarbon solvents, which have low polarity, but more resistant to moisture absorption. Polar resins behave in the opposite way. Strongly polar solvents, such as dimethyl sulphoxide or similar, can interact with polar structures in the resin and are difficult to resist. Crystalline thermoplastic polymers are often better for such applications. For example, polyethene will only dissolve in hydrocarbon solvents (of similar solubility parameter) at temperatures above the crystalline melting point. Polar semi-crystalline polymers such as the polyamides or nylons can be dissolved in highly polar solvents, such as cresol, because of a stronger interaction than that between molecules within the crystallites. High performance thermoplastic polymers such as polyether ether ketone (PEEK) have been promoted for their resistance to organic solvents (see Table 3.5) [12], The chemical resistance of unsaturated polyester and vinyl ester and urethane resins is indicated in Table 3.6 [15]. 

Chemicals interacting with polyether ether ketone (PEEK ) are not pH-dependent. However, this material is to be avoided with nitric, sulfuric, and halogenated acids such as HF, HBr, and HI. It can be usually employed with HCl, and also with pure halogen gases. In addition, it should be used carefully with methylene chloride, THE, and dimethyl sulfoxide (DMSO) in order to avoid swelling. 

There is, however, an Important practical difference between the reaction conditions required for successful operation of the routes to polyetherketones as compared with those for the polysulphones and this arises from a crucial difference between the two classes of polymers. Polyethersulphones are amorphous or only slightly crystalline and dissolve readily in polar organic solvents such as nitrobenzene or dimethyl sulphoxide at room temperature, but many polyetherketones develop considerable crystallinity and dissolve only at temperatures close to their melting points in this type of solvent. The insolubility of these polymers presented a major synthetic problan as it limits the molecular weights that could be obtained before the growing chains crystallised out from the polycondensation system and this is the main reason why commercial development of the polyetherketones lagged behind that of the polyethersulphones Solutions to this problem for the polyaroylation reactions, (1), were found first by du Pont and then by Raychem, while for the polyether syntheses the problem was solved by ICl. Raychem manufactured a polymer of structure 1, named Stilan, between 1972 and 1976, and manufacture of the ICI polymer, II, trade name Victrex PEEK", started in 1982. 

For DS <30%, sPEEK polymers are soluble in dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or A-methylpyrrolidone (NMP). For DS >50%, sPEEKs are soluble in A,iV-dimethylacetamide (DMAc) also at room temperature [151], while for DS above 60%, sPEEKs are highly swollen in methanol/water solution at 80-90 °C, and for these reasons, they are not suitable for DMFC applications [155]. For DS >70%, sPEEKs are soluble in methanol, and for DS = 100%, in hot water [182,183]. When PEEK sulfonation is carried out via the concentrated sulfuric acid procedure, it is limited and takes place only on the four chemically equivalent positions of the hydroquinone segment and the DS does not exceed the value of 100% owing to the electron-withdrawing deactivating... 

Attractive blends for PEMs with high proton conductivity have been made from sulfonated PES, PSU, polyetherketone (PEK), PEEK or poly(2,6-dimethyl 1,4-phenylene ether) (PPE) blended with polybenzimidazole (PBI) or polyetherimide (PEI). To preserve the desired PEM performance, the blends are often crosslinked by radiation, chemical reaction of ionic interactions. For long-term PEM applications it is important that membranes resistance to mechanical, chemical and thermal degradation is maximized. Accelerated aging tests should follow several membrane functionalities, for example conductivity, membrane integrity and permeability. The tests should also identify a possible cross-correlation of effects, namely stress on thermal and/or chemical degradation. 

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