Superlubricity in Gemini Hydrogels

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Angela A. Pitenis ◽  
Juan Manuel Urueña ◽  
Andrew C. Cooper ◽  
Thomas E. Angelini ◽  
W. Gregory Sawyer
Keyword(s):  
Friction Coefficient ◽  
Room Temperature ◽  
Mesh Size ◽  
Thermal Fluctuations ◽  
Low Friction ◽  
Contact Areas ◽  
Solvent Water ◽  
Aqueous Environments ◽  
Contact Pressures

Gemini hydrogels have repeatedly produced low friction under conditions generally not thought to be favorable to superlubricity: low sliding speeds, low contact pressures, macroscopic contact areas, and room temperature aqueous environments. A proposed explanation for this unique behavior is that thermal fluctuations at the interface are sufficient to separate the surfaces, with solvent (water) shearing in this region being the main source of dissipation. In this paper, we demonstrate that very soft and correspondingly large mesh size Gemini hydrogels show superlubricity with the lowest measured friction coefficient being μ = 0.0013 ± 0.0006.

Lubricity from Entangled Polymer Networks on Hydrogels

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Angela A. Pitenis ◽  
Juan Manuel Urueña ◽  
Ryan M. Nixon ◽  
Tapomoy Bhattacharjee ◽  
Brandon A. Krick ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Polymer Network ◽  
Polymer Networks ◽  
Mesh Size ◽  
Solution Polymerization ◽  
Hydrogel Sample ◽  
Low Friction ◽  
Aqueous Environments ◽  
Surface Measurements ◽  
Entangled Polymer

Structural hydrogel materials are being considered and investigated for a wide variety of biotribological applications. Unfortunately, most of the mechanical strength and rigidity of these materials comes from high polymer concentrations and correspondingly low polymer mesh size, which results in high friction coefficients in aqueous environments. Recent measurements have revealed that soft, flexible, and large mesh size hydrogels can provide ultra low friction, but this comes at the expense of mechanical strength. In this paper, we have prepared a low friction structural hydrogel sample of polyhydroxyethylmethacrylate (pHEMA) by polymerizing an entangled polymer network on the surface through a solution polymerization route. The entangled polymer network was made entirely from uncrosslinked polyacrylamide (pAAm) that was polymerized from an aqueous solution and had integral entanglement with the pHEMA surface. Measurements revealed that these entangled polymer networks could extend up to ∼200 μm from the surface, and these entangled polymer networks can provide reductions in friction coefficient of almost two orders of magnitude (μ > 0.7 to μ < 0.01).

Tribological Behavior of PTFE Nanocomposites Reinforced with PBA Grafted Alumina Nanoparticles

2012 ◽  
Vol 184-185 ◽  
pp. 1380-1383
Author(s):  
Yong Ping Niu ◽  
Xiang Yan Li ◽  
Jun Kai Zhang ◽  
Ming Han ◽  
Yong Zhen Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Wear Resistance ◽  
Friction Coefficient ◽  
Tribological Behavior ◽  
Compression Molding ◽  
Alumina Nanoparticles ◽  
Low Friction ◽  
Grafted Nanoparticles ◽  
Scanning Electron

Polybutyl acrylate (PBA) grafted alumina nanoparticles were synthesized. Polytetrafluoroethylene (PTFE) nanocomposites reinforced with PBA grafted nanoparticles were prepared by compression molding. The effects of PBA grafted nanoparticles on the tribological behavior of the PTFE nanocomposites were investigated on a tribometer. The abrasion mechanisms of the PTFE nanocomposites were investigated by scanning electron microscopy (SEM) of the abraded surfaces. The results show that the addition of PBA grafted nanoparticles maintains low friction coefficient and improves the wear resistance of the PTFE nanocomposites.

Observation of Cracks of PEEK Polymer Thrust Bearings under Rolling Contact Fatigue in Water

2016 ◽  
Vol 703 ◽  
pp. 172-177 ◽  
Author(s):  
Xiao Chen Shi ◽  
Masaya Orito ◽  
Yuji Kashima ◽  
Koshiro Mizobe ◽  
Katsuyuki Kida
Keyword(s):  
Corrosion Resistance ◽  
Friction Coefficient ◽  
Cross Sections ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Light Weight ◽  
Low Friction ◽  
High Corrosion Resistance ◽  
Thrust Bearings

Considering the advantages on light weight, low friction coefficient, high corrosion resistance and electric insulation, polymer bearings are widely used under certain environments, where the toughness like metal bearings is not necessary. In our previous study, it was concluded that the main reason for PEEK thrust bearings failure in water was flaking due to surface crack propagation. In the present study, crack observations were made on groove surfaces and cross sections along both radial and rolling directions in order to find the relation between cracks and flaking failures.

Research on Ti-GLC/TiCN/TiN composite multilayer coating with ultra-low friction coefficient in various environments

2021 ◽  
Vol 26 ◽  
pp. 101426
Author(s):  
Weiqing Yan ◽  
Zhiqiang Zhang ◽  
Yifan Zhang ◽  
Lin Chen ◽  
Xu Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Multilayer Coating ◽  
Low Friction
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