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Ether Ether Ketone (ether + ether_ketone)
Selected AbstractsInternal electrolyte temperatures for polymer and fused-silica capillaries used in capillary electrophoresisELECTROPHORESIS, Issue 22 2005Christopher J. Evenhuis Abstract Polymers are important as materials for manufacturing microfluidic devices for electrodriven separations, in which Joule heating is an unavoidable phenomenon. Heating effects were investigated in polymer capillaries using a CE setup. This study is the first step toward the longer-term objective of the study of heating effects occurring in polymeric microfluidic devices. The thermal conductivity of polymers is much smaller than that of fused silica (FS), resulting in less efficient dissipation of heat in polymeric capillaries. This study used conductance measurements as a temperature probe to determine the mean electrolyte temperatures in CE capillaries of different materials. Values for mean electrolyte temperatures in capillaries made of New Generation FluoroPolymer (NGFP), poly-(methylmethacrylate) (PMMA), and poly(ether ether ketone) (PEEK) capillaries were compared with those obtained for FS capillaries. Extrapolation of plots of conductance versus power per unit length (P/L) to zero power was used to obtain conductance values free of Joule heating effects. The ratio of the measured conductance values at different power levels to the conductance at zero power was used to determine the mean temperature of the electrolyte. For each type of capillary material, it was found that the average increase in the mean temperature of the electrolyte (,TMean) was directly proportional to P/L and inversely proportional to the thermal conductivity (,) of the capillary material. At 7.5,W/m, values for ,TMean for NGFP, PMMA, and PEEK were determined to be 36.6, 33.8, and 30.7°C, respectively. Under identical conditions, ,TMean for FS capillaries was 20.4°C. [source] SPEEK/Polyimide Blends for Proton Conductive MembranesPresented at the 1st CARISMA Conference, Progress MEA 2008, La Grande Motte, 21st,24th September 2008.FUEL CELLS, Issue 4 2009H. Maab Abstract A series of membranes, based on sulphonated poly(ether ether ketone) (SPEEK)/polyimide (PI) blends, was prepared at different casting conditions. They were characterised by SEM, FTIR, DMTA, DSC, TGA, water/methanol pervaporation and impedance spectroscopy. The membranes prepared at 130,°C from blends with 10, 20 and 30,wt.-% of PI are homogeneous, and the methanol permeabilities decreased from 28,×,10,10,kg,m,s,1,m,2 (plain SPEEK) to 7.21, 2.61 and 0.55,×,10,10,kg,m,s,1,m,2, respectively. This corresponds to a 4- to 57-fold methanol crossover reduction. With this improvement, by the introduction of PI, the power density of SPEEK-based membranes in DMFC tests could be greatly improved. [source] Kinetic study of the thermal degradation of poly(aryl ether ketone)s containing 2,7-naphthalene moietiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Si-Jie Liu Abstract The degradation of poly(aryl ether ketone) containing 2,7-naphthalene moieties was subjected to dynamic and isothermal thermogravimetry in nitrogen and air. The dynamic experiments showed that the initial degradation temperature, temperature for 5% weight loss, and temperature corresponding to the maximum degradation rate of poly(aryl ether ketone) containing 2,7-naphthalene moieties were a little higher than those of poly(ether ether ketone) and almost independent of the 2,7-naphthalene moiety content. The thermal stability of poly(aryl ether ketone) containing 2,7-naphthalene moieties in air was substantially less than that in nitrogen, and the degradation mechanism was more complex. The results obtained under the isothermal conditions were in agreement with the corresponding results obtained in nitrogen and air under the dynamic conditions. In the dynamic experiments, the apparent activation energies for the degradation processes were 240 and 218 kJ/mol in nitrogen and air for the second reaction stage as the heating rate was higher than 5°C/min. In the isothermal experiments, the apparent activation energies for the degradation processes were 222 and 190 kJ/mol in nitrogen and air, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Theoretical studies on structural and electrical properties of PES/SPEEK blend nanofiltration membraneAICHE JOURNAL, Issue 8 2009A. F. Ismail Abstract Polyethersulfone (PES) nanofiltration membranes were prepared using a simple dry-jet wet spinning technique with different contents of sulfonated poly(ether ether ketone) (SPEEK) ranging from 0 to 4 wt %. The structural parameters (rp and Ak/,x) and electrostatic properties (, and X) of the blend membranes were deduced by employing the combination of irreversible thermodynamic model, steric hindrance pore (SHP) model, and Teorell-Meyer-Sievers (TMS) model. The modeling results obtained have been analyzed and discussed. The mean pore radius and pore size distribution of the blends were also determined based on the theoretical models. The results showed that pore radius increased with increasing the concentration of SPEEK from 0 to 2 wt % but decreased with a further increase in SPEEK content. The water flux, however, showed a systematically increase with increasing SPEEK content. The SPEEK also showed significant effect on membrane electrical properties. Both effective charge density and ratio of effective charge density to electrolyte solution increased with increasing concentration of SPEEK in the dope solution, reaching a value of ,21.02 and ,2.29, respectively. The pore radius which was determined by using different transport models has also been analyzed and discussed. It is found that the addition of SPEEK into dope solution is one of the paramount parameters in developing the negatively charged nanofiltration membrane with enhanced water flux while retaining the pore radius in the nanometer range. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Sulfonated polybenzimidazoles: Proton conduction and acid,base crosslinkingJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2010Owen D. Thomas Abstract A series of soluble, benzimidazole-based polymers containing sulfonic acid groups (SuPBI) has been synthesized. SuPBI membranes resist extensive swelling in water but are poor proton conductors. When blended with high ion exchange capacity (IEC) sulfonated poly(ether ether ketone) (SPEEK), a polymer that has high proton conductivity but poor mechanical integrity, ionic crosslinks form reducing the extent of swelling. The effect of sulfonation of PBI on crosslinking in these blends was gauged through comparison with nonsulfonated analogs. Sulfonic acid groups present in SuPBI compensate for acid groups involved in crosslinking, thereby increasing IEC and proton conductivity of the membrane. When water uptake and proton conductivity were compared to the IEC of blends containing either sulfonated or nonsulfonated PBI, no noticeable distinction between PBI types could be made. Comparisons were also made between these blends and pure SPEEK membranes of similar IEC. Blend membranes exhibit slightly lower maximum proton conductivity than pure SPEEK membranes (60 vs. 75 mS cm,1) but had significantly enhanced dimensional stability upon immersion in water, especially at elevated temperature (80 °C). Elevated temperature measurements in humid environments show increased proton conductivity of the SuPBI membranes when compared with SPEEK-only membranes of similar IEC (c.f. 55 for the blend vs. 42 mS cm,1 for SPEEK at 80 °C, 90% relative humidity). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3640,3650, 2010 [source] Synthesis and properties of new fluorinated polymers bearing pendant imidazole groups for fuel cell membranes operating over a broad relative humidity rangeJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2010Guillaume Frutsaert Abstract New alternating copolymers comprising a chlorotrifluorinated backbone and imidazole-terminated pendant ethylene oxide groups have been prepared with a view to their use as a component of proton-conducting membranes in polymer electrolyte fuel cells. A vinyl ether containing an imidazole (Imi) function protected by a benzyl group (BVI) was first synthesized in a three-step reaction. It was then copolymerized in solution with chlorotrifluoroethylene (CTFE) by conventional radical copolymerization leading to alternating poly(BVI-alt-CTFE) copolymers in good yields. Deprotection of the benzyl group under hydrogen produced a chlorotrifluorinated poly(Imi-alt-CTFE) copolymer. The polymer was subsequently used to form blend membranes with sulfonated poly(ether ether ketone) (sPEEK). The conductivity of blend membranes of poly (Imi-alt-CTFE) with sPEEK lies in the range of 4,10 mS cm,1 at 40,70 °C and, for blend membranes rich in poly(Imi-alt-CTFE), is little dependent on relative humidity between 30 and 100%. It is surmised that the polymer and membrane composition favor microstructural phase separation into chlorotrifluorinated polymer backbone domains and regions in which imidazole groups are clustered. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 223,231, 2010 [source] Synthesis and characterization of poly(arylene ether)s derived from 4,4,-bishydroxybiphenyl and 4,4,-bishydroxyterphenylJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2002Arun Kashinath Salunke Abstract A series of poly(arylene ether)s were successfully prepared by aromatic, nucleophilic substitution reactions with various perfluoroalkyl-activated bisfluoromonomers with 4,4,-bishydroxybiphenyl and 4,4,-bishydroxyterphenyl. 4,4,-Bishydroxyterphenyl was synthesized through the Grignard coupling reaction of magnesium salt of 4-bromoanisole with dibromobenzene followed by demethylation with pyridine,hydrochloride. The products obtained by the displacement of fluorine atoms exhibited good inherent viscosity, up to 0.77 dL/g, and number-average molecular weights up to 69,300. These poly(arylene ether)s showed very good thermal stability, up to 548 °C for 5% weight loss according to thermogravimetric analysis under synthetic air, and high glass-transition temperatures, up to 259 °C according to differential scanning calorimetry, depending on the exact repeat unit structure. These polymers were soluble in a wide range of organic solvents, such as N -methylpyrrolidone, dimethylformamide, tetrahydrofuran, toluene, and CHCl3, and were insoluble in dimethyl sulfoxide and acetone. Thin films of these poly(arylene ether)s showed good transparency and exhibited tensile strengths up to 132 MPa, moduli up to 3.34 GPa, and elongations at break up to 84%, depending on their exact repeating unit structures. These values are comparable to those of high-performance thermoplastic materials such as poly(ether ether ketone) (PEEK) and Ultem poly(ether imide) (PEI). These poly(arylene ether)s exhibited low dielectric constants. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 55,69, 2002 [source] Finite-element heat-transfer analysis of a PEEK-steel sliding pair in a pin-on-disc configurationLUBRICATION SCIENCE, Issue 1 2001László Kónya Abstract Finite-element (FE) thermal models have been developed in order to study the temperature distribution in a sliding pair comprising a poly(ether ether ketone) (PEEK) pin and a steel disc in a pin-on-disc configuration. First, a moving heat source model for the disc was created. An alternative distributed heat source model was also produced in order to reduce computing time for the evaluation of the moving heat source model by some orders of magnitude. This latter model gave the same results as the moving heat source model, except for a small region just below the moving heat source. On the basis of the distributed heat source approach, a complete axisymmetric FE model for the disc side (taking the effect of thermal resistance between the assembled components into consideration) and a steady-state quarter model for the pin were developed. Water cooling and air cooling of the steel shaft were also compared. It was found that air cooling allowed a higher temperature in the contact region of the two sliding partners. The experimental results obtained with thermocouples and a thermal camera showed good agreement with the model predictions. [source] Permeability and Conductivity Studies on Ionomer-Polysilsesquioxane Hybrid MaterialsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 3 2006Chedarampet S. Karthikeyan Abstract Summary: Hybrid materials based on sulphonated poly(ether ether ketone) (SPEEK, ionomer) and (RSiO1.5)n network (polysilsequioxane) were prepared by sol-gel process. Two different precursors namely aminopropyl trimethoxysilane (APTMS) and imidazoleglycidoxypropyl trimethoxysilane (IGPTMS) were utilized to generate (RSiO1.5)n in SPEEK matrix by sol-gel process. 29Si MAS NMR confirmed the formation of RSiO3/2 network structure inside the matrix. Characterisation of the hybrid materials showed lower methanol and water permeability compared to the plain SPEEK. They are therefore promising materials as membranes for direct methanol fuel cells applications. The hybrid material derived from amino group was more effective in decreasing the permeability than the material derived from imidazole group. However, the proton conductivity of the latter was higher than the material derived from amino group. The results indicate that hybrid material prepared from imidazole containing silane is more suitable as a membrane for direct methanol fuel cell than the one prepared from amino carrying silane because it fulfils the two main requirements, namely low methanol permeability and reasonably good proton conductivity. Figure shows a network of silica phase in SPEEK matrix. [source] Dielectric Response of Aramid Fiber-Reinforced PEEKMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2002Nina Korbakov Abstract Dielectric spectroscopy was applied for the first time to aramid fiber-reinforced PEEK, wherein the effect of the fiber on the dielectric response was examined for both amorphous and crystalline poly(ether ether ketone) (PEEK) over wide temperature and frequency ranges. Whereas the temperature behavior of the dielectric losses of the materials exhibited the typical , and , processes of PEEK, the specific effect of the fibers in the crystalline PEEK was revealed in shifting the , process to a higher temperature. The unique effect of the fibers was expressed by a significantly higher activation energy and lower dielectric strength for the , relaxation, reflecting a higher constraint level that is imposed by the fiber. It is proposed that this additional constraint is associated with fiber generated transcrystallinity. Scanning electron micrograph of transverse fracture surface of crystallized unidirectional aramid fiber-reinforced PEEK. [source] Kinetic analysis of thermo-oxidative degradation of PEEK/thermotropic liquid crystalline polymer blendsPOLYMER ENGINEERING & SCIENCE, Issue 2 2006M. Naffakh The thermal degradation behavior of blends of poly(aryl ether ether ketone), PEEK, with a thermotropic liquid crystalline polymer (TLCP), Vectra®, were investigated in an oxidative atmosphere, using thermogravimetric analysis under dynamic conditions. The theoretical weight loss curves of the blends were compared with the experimental curves in order to explain the effect of blending on the thermal stability of the pure polymers. The thermo-oxidative degradation of PEEK/Vectra® blends of different compositions takes place in various steps and the characteristic degradation temperatures and the kinetic parameters such as activation energy are strongly influenced by blending. Polymer blends based on this TLCP polymer had not been previously studied from kinetic viewpoint. POLYM. ENG. SCI. 46:129,138, 2006. © 2005 Society of Plastics Engineers [source] Preparation of highly H+ permeable sulfonated poly(ether ether ketone) cation exchange membranes and their applications in electro-generation of thioglycolic acidPOLYMER INTERNATIONAL, Issue 7 2009Xuehong Huang Abstract BACKGROUND: Sulfonated poly(ether ether ketone) (SPEEK) was successfully synthesized from sulfonated 4,4,-difluorobenzophenone, 4,4,-difluorobenzophenone and bisphenol A. SPEEK cation exchange membranes were prepared by the casting method. The composition and morphology of SPEEK were characterized using Fourier transform infrared and 1H NMR spectroscopies, respectively. The ion exchange capacity (IEC), water uptake and degree of swelling of the membranes were also investigated. SPEEK120 was used as a separator in an electrolysis cell to produce thioglycolic acid (TGA). RESULTS: SPEEK polymerization was carried out at 145 and 175 °C for 10 h. The IEC of the SPEEK membranes was measured as 0.24,2.02 meq g,1 and the water uptake as 2.26,26.45%. The degree of swelling of the membranes was 1.71,15.28%. TGA was effectively prepared by electro-reduction of dithioglycolic acid. The current efficiency peaked at 58.31% at room temperature with a current density of 15 mA cm,2. CONCLUSION: SPEEK120 membrane shows good dimensional stability and H+ permeability. Compared to the traditional metal-reduction method, the current electro-reduction technique avoids the use of zinc powder and so reduces environmental pollution. Copyright © 2009 Society of Chemical Industry [source] Thermal properties, structure and morphology of PEEK/thermotropic liquid crystalline polymer blendsPOLYMER INTERNATIONAL, Issue 12 2003Mohammed Naffakh Abstract The dynamic crystallization and subsequent melting behaviour of poly(aryl ether ether ketone), PEEK, and its blends with a thermotropic liquid crystalline polymer, Vectra®, have been studied using differential scanning calorimetry, optical microscopy and wide-angle and small-angle X-ray diffraction (WAXS and SAXS) techniques in a wide compositional range. Differences in crystallization rates and crystallinities were related to the structural and morphological characteristics of the blends measured by simultaneous real-time WAXS and SAXS experiments using synchrotron radiation and optical microscopy. The crystallization process of PEEK in the blends takes place in the presence of the nematic phase of Vectra and leads to the formation of two different crystalline families. The addition of Vectra reduces the crystallization rate of PEEK, depending on composition, and more perfect crystals are formed. An increase in the long period of PEEK during heating was generally observed in the blends at all cooling rates. Copyright © 2003 Society of Chemical Industry [source] Nanofiller-reinforced polymer nanocompositesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2008J. Njuguna Abstract In this work, the technology of nano- and micro-scale particle reinforcement concerning various polymeric fiber-reinforced systems including polyamides (PAs), polyesters, polyurethanes (PUs), polypropylenes (pps), and high-performance/temperature engineering polymers such as polyimide (PI), poly(ether ether ketone) (PEEK), polyarylacetylene (PAA), and poly p -phenylene benzobisoxazole (PBO) is reviewed. When the diameters of polymer fiber materials are shrunk from micrometers to submicrons or nanometers, there appear several unique characteristics such as very large surface area to volume ratio (this ratio for a nanofiber can be as large as 103 times of that of a microfiber), flexibility in surface functionalities and superior mechanical performance (such as stiffness and tensile strength) compared to any other known form of the material. While nanoparticle reinforcement of fiber-reinforced composites has been shown to be a possibility, much work remains to be performed in order to understand how nanoreinforcement results in dramatic changes in material properties. The understanding of these phenomena will facilitate their extension to the reinforcement of more complicated anisotropic structures and advanced polymeric composite systems. Copyright © 2008 John Wiley & Sons, Ltd. [source] Physicochemical and electrochemical characterizations of organic montmorillonite (OMMT)/sulfonated poly(ether ether ketone) (SPEEK) composite membranesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010R. Gosalawit Abstract Physicochemical and electrochemical properties of the organic montmorillonite (OMMT)/sulfonated poly(ether ether ketone) (SPEEK) composite membranes are considered for their use as proton conducting membranes. The paper presents the preparation and characterization of SPEEK and its composite membranes with OMMT as well as their comparison to the reference Nafion® 117 membrane. Water uptake and thermal property (Td1) are improved when the OMMT loading content increases. Methanol permeability decreases as OMMT loading content increases up to as high as 53% (5 wt% OMMT/SPEEK composite membrane). For proton conductivity, all membranes show improvement when the operating temperature increases from 25 to 90 °C. The proton conductivity at 100 °C of 3 wt% OMMT/SPEEK composite membrane (5.6 × 10,2 S/cm) is one order of magnitude higher than that of Nafion® 117 (2 × 10,3 S/cm). Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Photochemically Cross-linked Poly(aryl ether ketone) RingsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 23 2006Ian Teasdale Abstract Summary: Macrocyclic phenyl ether ketones were prepared via pseudo high dilution condensation. Irradiation of these rings with UV light in a solution containing isopropyl alcohol as hydrogen donor resulted in a photo-induced reduction of benzophenone to benzopinacol and the formation linked macrocycles. These rings can be heated to undergo ring-opening polymerization and produce a polymer network or they can be added to a polycondensation reaction to prepare poly(ether ether ketones) with variable degrees of cross-linking. Photochemical cross-linking of PEK rings and ring opening polymerization (n: 2,6). (a) h,, iPrOH, DCM; (b) CsF, 260,°C (polymer 3); (c) 4,4,,difluorobenzophenone, hydroquinone, diphenylsulphone, K2CO3, 260,°C (2% polymer 4; 6% polymer 5). [source] New poly ether ether ketones containing phosphorus for membrane preparationASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Francesco Trotta Abstract In this study is reported the synthetic procedure and the characterisation of novel phosphorus containing polyether ether ketone (PEEK-P). The new polymer was synthesized via direct polycondensation of 2,2-bis(3-diethylphosphono-4-hydroxyphenyl)-propane and 4,4,-difluorobenzophenone according to well known general procedure and was extensively characterized by using infrared spectroscopy (FT-IR), thermogravimetric analyses (TGA), viscosity measurements and ,H-NMR analysis. The obtained polymer is soluble in some organic solvents and the solution of phosphonated polymer could be used to obtain membranes by using the phase inversion technique. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||||||||