Modification PEEKS

Upadhyay et al. [98] used primarily correlated XPS and water contact angle measurements to study the surface degradation and recovery of amorphous films of a PMMA and a poly (aryl ether ether ketone) (PEEK). Surface modification of the films was carried out in a dielectric barrier discharge (DBD) unit, samples being treated with different dose levels of dielectric discharge. The modified (treated) samples were then stored for one month and re-examined. Figure 35 shows C(ls) and 0(1 s) XPS envelopes and their curve-fitting deconvolutions,... 

Sulfonation is very useful chemical modification of polymer, as it induces high polarity in the polymer changing its chemical as well as physical properties. Sulfonated polymers are also important precursors for ionomer formation [75]. There are reports of sulfonation of ethylene-propylene diene terpolymer (EPDM) [76, 77], polyarylene-ether-sulfone [78], polyaromatic ether ketone [79], polyether ether ketone (PEEK) [80], styrene-ethylene-butylene-styrene block copolymer, (SEBS) [81]. Poly [bis(3-methyl phenoxy) phosphozene] [82], Sulfonated polymers show a distinct peak at 1176 cm"1 due to stretching vibration of 0=S=0 in the -S03H group. Another peak appears at 881 cm 1 due to stretching vibration of S-OH bond. However, the position of different vibrational bands due to sulfonation depends on the nature of the cations as well as types of solvents [75, 76]. 

Another approach to covalently attach carbon nanotubes is based on the chemical modification of a PEEK matrix which allows further covalent interaction with functionalized carbon nanotubes. In 2007 Babaa et al. (40) proposed a route to covalently graft commercial MWCNTs by using this approach. The process initiates by dissolution of PEEK in concentrated H2S04, leading to functionalization yields of 70%. MWCNTs covalently functionalized with... 

An engineering plastic core was found preferable examples included polyetherether ketone (PEEK), polyphenylene sulfide (PPS), and polyether imide (PEI). Polytetrafluoroethylene bearers were placed in the mold to keep the core material away from the walls of the mold. No special cavity modifications were required. Any hot-melt fluoroplastic could be molded surrounding the insert examples include PVDF, FEP, ETFE, PFA, ECTFE, and PCTFE. 

The surface properties of PEEK can be controlled by functionalization of the surface. For example, surface modified PEEK films can be used in the field of cell cultivation. Therefore, there is a certain interest in surface modification. 

Another method of surface modification is oxygen plasma treatment. Oxygen plasma treatment also affects surface topography, by unveiling the spherulitic structure of PEEK. ... 

Other filler materials are hydroxyapatite, aluminum oxide and aluminum nitride. In addition, nanofillers are used. PEEK polymer filled with nano sized silica or alumina fillers of 15-30 nm exhibit an improvement of the mechanical properties by 20-50%. The agglomeration tendency can be somewhat dimiiushed by a modification of the surface of the fillers with stearic acid. °... 

Zhang H, Fan X, Zhang J, Zhou Z (2008) Modification research of sulfonated PEEK membranes used in DMFC. Solid State Ion 179 1409-1412... 

Two experimental poly(ether ether ketone) (PEEK) membranes for methanol fuel cell application, one with a zirconium modification to reduce the methanol crossover (samples PEEK-sn-0 and PEEK-sn-Zr, respectively), which were prepared and kindly submitted by Dr. S. Nunes (GKSS, Germany) (Nunes et al. 2002 Silva et al. 2006). To observe the electrical changes only due to membrane material modification, impedance measurements with these membranes were performed both in contact with the NaCl solutions and in a dry state. 

Furthermore, the PEEK sulfonation can be realized introducing directly the sulfonic acid group onto the polymer back-bone [5-7] by modification or by polymerizing suUbnated monomers [8,9],... 

PEEK modifieation procedure such as chemical polymerization with polyaniline or PEEK chemical modification as the PEEK-WC, useful in PEMFC/DMFC application in sulfonated form or like blend with zireonia oxides. 

A modification of the procedure has also been developed for PEEK. Olley, Bassett and Blundell [279] found that a 2% w/v solution of potassium permanganate in a mixture of 4 volumes of orthophosphoric acid and 1 volume of water was effective. Samples were etched at room temperature for 50 min, then etching was stopped by adding the reagent to twice the volume of hydrogen peroxide solution followed by washing and replication. The method clearly revealed the spherulitic detail in PEEK [279]. 

PARK are frequently used without surface modification. There are a significant number of papers and patents which describe PEEK modified with fillers such as hydroxyapatite (HA) or calcium phosphates, titanimn coatings or even biomimetic protein and peptide sequences. Some of these are described in reference [2]. However, in HA-filled PARK there is a trade-off between mechanical properties and modified biocompatibility. Various attempts have been made to overcome this limitation - for example by using HA coatings or HA whiskers [3, 4]. Biological modifications would be subject to extremely complex regulatory approval. In fact unmodified PEEK has been shown to be comparable in vitro with the bone forming capacity of titanium [5]. 

The most studied anti-wear material modified by whiskers is PEEK. Wang et al." compared the performances of PEEK before and after modification with potassium titanate whiskers. The friction and wear performances of the latter showed obvious improvement over the former. Under 300 N, the wear resistance of the latter increases 2.64 and 2.11 times than the former, respectively. In addition, calcium carbonate whiskers have an excellent anti-friction effect on PEEK composite material. When the whisker content is less than 15%, the wear rate of the material decreases dramatically. The wear rate of the... 

High performance polymers, such as poly(ether-ether ketone), PEEK, as well as new resins, still coming on stream, such as polyfethylene naphthalate), syndiotactic polystyrene, and cyclo-olefinic copolymers, are offering further challenges to impact modification. 

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