Proton Conducting Composite Membranes from Sulfonated Polyether Ether Ketone and SiO_2

Proton conducting composite membranes from sulfonated polyether ether ketone and SiO2 for direct methanol fuel cell （DMFC） application were prepared with sulfonated polyether ether ketone（SPEEK） and tetracethoxy silane（TEOS） by sol-gel method. The covalent crosslinking structure was formed between —SO3H of SPEEK via SiO2. The SEM images show that the interfacial compatibility of SPEEK and SiO2 is improved obviously and SiO2 disperses uniformly in the polymer matrix and the particle diameter of SiO2 does not exceed 40 nm. The proton conductivity of composite membranes decreases slightly compared with the SPEEK membrane while the methanol permeability and swelling of composite membrane are improved remarkablely owing to covalent cross-linking between —SO3H and SiO2 .

Friction and wear performance of polyether ether ketone(PEEK)polymers in three lubrication regimes

This experimental study investigates the friction and wear of three coatings commonly used in industrial applications,particularly in hydrodynamic bearings.The three materials under investigation were Babbitt,polyether ether ketone(PEEK)reinforced with 15%carbon fibers,and PEEK reinforced with 20%carbon fibers.The first polymer material was extruded,while the other was produced by fused deposition modelling(FDM).The materials were subjected to sliding tests in a pin-on-disc configuration,with a steel ball serving as the counter surface.The tests were conducted at room temperature,with a load of 10 N and under three different lubrication conditions:dry,grease,and oil.The linear speed was set at 0.3 m/s for the dry and semi-solid lubrication tests,while for the oil tests,the speed was set at 0.25 m/s.The greases used had consistency grades of NGLI 000 and NGLI 2.An ISO VG 68 circulation oil was used for the oil lubrication tests.Additionally,thermodynamic analyses were performed under the most severe conditions(i.e.,dry)to investigate the steel-Babbitt and steel-PEEK contact.

Molding of polyether ether ketone(PEEK)and its composites:a review

Over the last half-century,polyether ether ketone(PEEK)has emerged as a widely adopted thermoplastic polymer,primarily due to its lower density,exceptional mechanical properties,high-temperature and chemical resistance,and biocompatibility.PEEK and its composites have found extensive applications across various fields,including machinery,aerospace,military equipment,electronics,and biomedicine,positioning themselves as promising substitutes for traditional metal structures.Nevertheless,achieving optimal performance and functional molding of PEEK and its composites presents a formidable challenge,given their inherent characteristics,such as semi-crystallinity,high melting temperature,heightened viscosity,low dielectric coefficient,and hydrophobic properties.In this paper,we present a comprehensive review of the molding methods and processes of PEEK and its composites,including extrusion molding,hot compression molding,injection molding,and 3D printing.We also introduce typical innovative applications within the fields of mechanics,electricity,and biomedicine while elucidating methodologies that leverage the distinctive advantages of PEEK and its composites.Additionally,we summarize research findings related to manipulating the properties of PEEK and its composites through the optimization of machine parameters,process variables,and material structural adjustments.Finally,we contemplate the prevailing development trends and outline prospective avenues for further research in the advancement and molding of PEEK and its composites.

Polymeric 32-channel arrayed waveguide grating multiplexer using fluorinated poly (ether ether ketone)

In wavelength division multiplexing (WDM) systems, arrayed waveguide grating (AWG) multiplexer is a key component. Polymeric AWG multiplexer has recently attracted much attention due to its low cost processing and a potential of integration with other devices. Fluorinated polyether ether ketone (FPEEK) is excellent material for fabrication of optical waveguides due to its low absorption loss at 1.55-μm wavelength and high thermal stability. A 32-channel AWG multiplexer has been designed based on the grating diffraction theory and fabricated using newly synthesized FPEEK. During the fabrication process of the polymer/Si AWG device, spin coating, vaporizing, photolithographic patterning and reactive ion etching (RIE) are used. The AWG multiplexer measurement system is based on a tunable semiconductor laser, an infrared camera and a Peltier-type heater. The device exhibits a wavelength channel spacing of 0.8 nm and a center wavelength of 1548 nm at room temperature.

STATIC AND FATIGUE BEHAVIOR OF IMPACTED AS4/PEEK THERMOPLASTIC COMPOSITES UNDER COMPRESSION LOAD

Static and fatigue tests under compression load were made on impacted AS4/PEEK and T300/913C graphite/epoxy with [45/90/-45/0]5S stacking sequence. The comparison of the damage tolerance assessment for thermosetting and thermoplastic composites shows that thermoplastics are more damage tolerant under compression. Impacted thermoplastic composites have excellent compression-compression fatigue behavior. The damage growth life is only a few percent of their total fatigue life and no regular damage growth can be found. Some design principles for thermosetting composite structures may still be used.

High Proton Conducting SPEEK/SiO_2/ PWA Composite Membranes for Direct Methanol Fuel Cells

Sulfonated polyether ether ketone （SPEEK） based composite membranes for direct methanol fuel cell （DMFC） application were prepared by sol-gel reaction of tetraethoxysilane （TEOS） in the SPEEK matrix and the incorporation of phosphotungstic acid （PWA）.The conductivity of the developed membranes was determined by impedance spectroscopy and the methanol permeability through the membranes was obtained from diffuseness experiments.The SEM images show that the addition of SiO2 and the covalent cross-linking structure lead to fine PWA particles and more uniformly dispersion.The swelling of composite membranes remains in the range of 5%-8% at 30-90 ℃ and the effusion of PWA reduces significantly.The composite membranes show a good balance in higher proton conductivity and lower methanol permeation.The cell with composite membrane has higher open circuit voltage（0.728 V） and higher peak power density（45 mW/cm2） than that with Nafion117.

Experimental study on the feasibility of alternative materials for tilting pad thrust bearings operating in transition to mixed friction

In hydrodynamic bearings traditional bearing alloys:Babbitts and bronzes are most frequently utilized.Polymer sliding layers are sometimes applied as a valuable alternative.Hard diamond-like carbon(DLC)coatings,which are also considered for certain applications may show some advantages,as well.Although material selection is of secondary importance in a full film lubrication regime it becomes important in mixed friction conditions,which is crucial for bearings with frequent starts and stops.Experimental research aimed at studying the performance of fluid film bearings in the specific operating regime,including the transition to mixed friction,is described in the paper.The tests were carried out on four tilting pad bearings of different material compositions:Steel/bronze,DLC/steel,steel/polyether ether ketone(PEEK),and steel/Babbitt.The tests comprised stopping under load and reproduction of the Stribeck curve by decreasing rotational speed to very low values,and observing the changes of friction force during the transition to mixed friction regime.Analysis of the transition conditions and other results showed clear differences between the tested bearings,illustrating the feasibility of less popular material compositions for bearings operating in specific conditions.More specifically,the DLC/steel bearing was demonstrating superior performance,i.e.lower friction,transition to mixed friction occurring at higher load,and more stable performance at start-stop regime over the other tested bearings.

Tribology of self-lubricating high performance ATSP,PI,and PEEK-based polymer composites up to 300℃

High-performance polymers(HPPs)are increasingly used in different industrial machinery components,particularly for rubbing parts that demand reliable and durable operation at extreme sliding conditions such as elevated temperature environments,where the use of conventional lubricants is not feasible.The current study investigates the role of environmental temperature on the tribological properties of three advanced HPPs,namely aromatic thermosetting copolyester(ATSP),polyimide(PI),and polyether ether ketone(PEEK)based polymer composites.Tribological experiments were carried out at different environmental temperatures from room temperature up to 300℃,and under dry sliding conditions.Specific attention was given to the role of temperature on the development of transfer films and its subsequent effect on the tribological performance.The ATSP composite was recommended as the best performing material,based on the overall tribological performance at all examined operating temperatures.

A sulfonated modification of PEEK for ultralow friction

Polyether ether ketone(PEEK)is a widely used material for friction pairs due to its excellent mechanical strength,good wear resistance,and chemical inertness.However,some modifications are necessary when PEEK is used as a water-lubricated friction pair.In this study,a novel sulfonation method was developed to design a water-lubricated friction pair with ultralow friction,good wear resistance,and high loading capacity.PEEK powders were sulfonated using ClSO3H and sintered to form bulk plastic.The sulfonated PEEK(SPEEK)plastic exhibited good tribological properties.At a low sliding speed,the friction coefficient was smaller than 0.02 when a 3 wt% NaCl solution was used as the lubricant.The order of magnitude of the wear rate was as low as 10^(-8) mm^(3)/(N·m).The mechanism of friction reduction was mainly hydration lubrication.The negatively charged -SO_(3)^(-) groups on the friction pair can adsorb hydrated Na+cations by electrostatic interactions.These hydrated Na+cations have a high load capacity and low shearing resistance.The ultralow wear mechanism observed in this study is possibly due to ultralow friction properties of the friction pairs prepared through the proposed sulfonation and thermoforming procedures.