XPS and transport studies of PVA-PPy and PSt-PBTh composites

Samir, F.; Seddik, E.B.; Corraze, B.; Bernède, Christian; Morsli, M.; Bonnet, A.; Conan, A.; Lefrant, S.

doi:10.1016/0379-6779(94)02476-f

Cited by 8 publications

(1 citation statement)

References 5 publications

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“…In the C 1s spectra, the peaks with the binding energy of 284.8 and 286.6 eV correspond to aliphatic carbons (CC and CH) and CO bond, respectively, which are derived from carbon contaminants in the air or PVA. ,, The relative intensity of the CO peak in the C 1s spectrum of the PVA-lubricated surface is significantly higher than those observed in the spectra of the surface acquired after running-in with HP and lubricating with PVA/NaCl, which indicates that surface adsorbents are more obvious. In the O 1s spectra, the peak at 532.2 eV is assigned to O–Si of SiO 2 , and the peaks at 532.7 and 532.8 eV are assigned to HOC and HOH, respectively, which correspond to the oxygen bonds in PVA and H 2 O. ,− PVA is known to be a water-soluble polymer that naturally contains some water. The obtained XPS results prove that PVA was adsorbed on the Si 3 N 4 ball surface.…”

Section: Resultsmentioning

confidence: 99%

Extreme-Pressure Superlubricity of Polymer Solution Enhanced with Hydrated Salt Ions

Bai

et al. 2020

Langmuir

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The development of new routes or materials to realize superlubricity under high contact pressure can result in energysaving and reduction of emissions. In this study, superlubricity (μ = 0.0017) under extreme pressure (717 MPa, more than twice the previously reported liquid superlubricity) between the frictional pair of Si 3 N 4 /sapphire was achieved by prerunning-in with a H 3 PO 4 (HP) solution followed by lubrication with an aqueous solution consisting of poly(vinyl alcohol) (PVA) and sodium chloride (NaCl). Under the same test condition, the aqueous PVA lubricant did not show superlubricity. Results of X-ray photoelectron spectroscopy and Raman spectroscopy indicate the formation of a PVA-adsorbed film at the frictional interface after lubrication with PVA but not after lubrication with PVA/NaCl, indicating competitive adsorption between hydrated Na + ions and PVA molecules. The hydrated Na + ions adsorbed preferentially to the solid surfaces, causing the transformation of the shear interface from a polymer film/polymer film to a solid/polymer film. Meanwhile, the hydrated Na + ions also produced hydration repulsion force and induced low shear stress between the solid surfaces. Furthermore, NaCl increased the viscosity of the polymer lubricant, enhanced the hydrodynamic effect between interfaces, and decreased direct contact between the friction pair, causing a further reduction in friction. Thus, the superlubricity of the PVA/NaCl mixture is attributed to the combination of hydration and hydrodynamic effects. This study provides a novel route and mechanism for achieving extreme-pressure superlubricity at the macroscale, through the synergistic lubricating effect of hydrated ions and a polymer solution, propelling the industrial application of superlubricity.

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Section: Resultsmentioning

confidence: 99%

Extreme-Pressure Superlubricity of Polymer Solution Enhanced with Hydrated Salt Ions

Bai

et al. 2020

Langmuir

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Degradation of polyvinyl alcohol under mechanothermal stretching

et al. 2013

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Mechanical and thermal properties of polyvinyl alcohol (PVA) are characterized and analyzed using in situ X-ray photoelectron spectroscopy (XPS) and quantum chemistry calculations. It is found that the carbon peaks-commonly used as the reference for spectroscopic analysis-shift under mechanical and thermal stretching. Results also indicate that, at different temperatures and among the various functional groups present in PVA, the carbon in the C-O group is the most stable. Computational calculations showed that Hartree-Fock/10-31G (d) reproduces the binding energy of core carbon electrons with an accuracy of 95%, which is enough to characterize bonds, allowing the results of the spectroscopic analysis to be corroborated.

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