Nano-scale friction of polystyrene in air and in vacuum

Bistac, Sophie; Schmitt, Marjorie; Ghorbal, Achraf; Gnecco, Enrico; Meyer, Ernst

doi:10.1016/j.polymer.2008.06.032

Cited by 14 publications

(12 citation statements)

References 52 publications

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“…Sliding (dynamic) friction data was measured in volts and is reported as half of the difference between trace and retrace signals for the central 800 nm region of each scan line (thus excluding any scanning tip trace–retrace turnaround contributions attributable to static friction). This data is directly proportional to friction , and was not converted to absolute friction force values because of the dependency upon which method is adopted to measure the lateral spring constant. ,− Even if the method used to determine the lateral spring constant was completely reliable, friction coefficients are still very dependent on the measurement system employed and the various parameters involved (scan rate, contact area, counter surface, etc). − Hence, for the purpose of the present study, the tribological experiments were undertaken by utilizing an internal reference, namely, the ATRP-grafted poly(NaStS) brushes tethered to a pulsed-plasma-deposited poly(VBC) layer. The 3 Hz scan rate of the AFM gives rise to a tip movement speed of 6 μm s –1 .…”

Section: Methodsmentioning

confidence: 99%

Tailoring the Density of Surface-Tethered Bottlebrushes

2011

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Surface-tethered bottlebrushes have been prepared by ATRP grafting of the macroinitiator brush backbone onto plasmachemical-deposited poly(vinylbenzyl chloride) initiator nanofilms followed by ATRP growth of the side chains (bristles). The surface density of bottlebrushes can be precisely tailored by varying the plasmachemical deposition parameters employed for producing the poly(vinylbenzyl chloride) initiator nanolayers. Lateral force scanning probe microscopy has shown that poly(glycidyl methacrylate)-graft-poly(sodium styrene sulfonate) bottlebrush-decorated surfaces give rise to an enhancement in lubrication.

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Section: Methodsmentioning

confidence: 99%

Tailoring the Density of Surface-Tethered Bottlebrushes

2011

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“…Flow within the tube was approximated under the assumption of no axial flow, no azimuthal change, and no radial flow. On the basis of these assumptions, a simplified version of the Navier-Stokes equation could be written in cylindrical coordinates, where u, azimuthal velocity; η, dynamic viscosity; ρ, fluid density; r, radius; and p, pressure-see Equations (10) and (11). This approach was already used by Fuchs and Drahm [31] for cylindrical geometries.…”

Section: Resonator Modelingmentioning

confidence: 99%

“…These sensors are robust, have no moving parts, and are, therefore, suited to real-time measurements. Using sensors based on resonance, various materials can be investigated for different purposes, such as studying the viscoelastic behavior of polymers, determining fluid density and viscosity [1][2][3][4][5][6][7][8], characterizing the mechanical properties of polymer membranes and thin films [9][10][11][12][13][14], and detecting biomolecule or nanoparticle masses [15][16][17][18][19][20]. Sensors using torsional vibration are a subgroup of mechanical resonators.…”

Section: Introductionmentioning

confidence: 99%

Analysis of a Tubular Torsionally Resonating Viscosity–Density Sensor

Brunner

Goodbread²,

Häusler³

et al. 2020

Sensors

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This paper discusses a state-of-the-art inline tubular sensor that can measure the viscosity–density ( ρ η ) of a passing fluid. In this study, experiments and numerical modelling were performed to develop a deeper understanding of the tubular sensor. Experimental results were compared with an analytical model of the torsional resonator. Good agreement was found at low viscosities, although the numerical model deviated slightly at higher viscosities. The sensor was used to measure viscosities in the range of 0.3–1000 mPa·s at a density of 1000 kg/m3. Above 50 mPa·s, numerical models predicted viscosity within ±5% of actual measurement. However, for lower viscosities, there was a higher deviation between model and experimental results up to a maximum of ±21% deviation at 0.3 mPa·s. The sensor was tested in a flow loop to determine the impact of both laminar and turbulent flow conditions. No significant deviations from the static case were found in either of the flow regimes. The numerical model developed for the tubular torsional sensor was shown to predict the sensor behavior over a wide range, enabling model-based design scaling.

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“…On the nano-level, friction is largely influenced by air humidity [14][15][16] as well as the water absorbed by the contact interface surfaces due to capillary action [17]. LFM determination of the impact of humidity on the friction at the nano-level, under the atmospheric pressure and vacuum, was reported in Bistac et al [18]. In this case, the friction in vacuum decreases with the increase of sliding speed, while, under normal pressure conditions, the friction ramps up with the sliding speed, due to absorbed water at the contact interface layer.…”

Section: Introductionmentioning

confidence: 97%

The Influence of Vacuum Level on the Friction Force Acting on the Pneumatic Cylinder Sealing Ring

et al. 2019

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Presented in this paper are the results of measurement of friction force acting on the pneumatic cylinder sealing rings under high vacuum atmosphere. The investigations were conducted at relatively low levels of sliding speed of the sealing ring. Special device was constructed and implemented to facilitate this experiment. The results indicate the importance of the vacuum level on the friction force magnitude. Higher vacuum levels influence significant increase of friction force. Special phenomenon is the decreasing of friction force at higher sliding speeds of the sealing ring along the cylinder, under the constant vacuum level. Therefore, detailed examination of this phenomenon in the domain of high sliding speeds could yield interesting results.

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Nano-scale friction of polystyrene in air and in vacuum

Cited by 14 publications

References 52 publications

Tailoring the Density of Surface-Tethered Bottlebrushes

Tailoring the Density of Surface-Tethered Bottlebrushes

Analysis of a Tubular Torsionally Resonating Viscosity–Density Sensor

The Influence of Vacuum Level on the Friction Force Acting on the Pneumatic Cylinder Sealing Ring

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