title: Study on the friction of κ-carrageenan hydrogels in air and aqueous environments.
abstract: Understanding the friction mechanism of polysaccharide hydrogels, which is the key component of human cartilage that has very low friction coefficient, is critical to develop next generation artificial joint replacement materials. In this study, the friction of the polysaccharide κ-carrageenan hydrogel was investigated to elucidate the effect of external load, cross-linking density, velocity, and environment on friction. Our experimental results show that (1) coefficient of friction (COF) decreases with normal load in air and remains constant in water, (2) increasing cross-linking density concurrently increases friction and is proportional to Young's modulus, (3) COF increases with testing velocity in both air and water, and (4) friction is reduced in aqueous environment due to the lubricating effect of water. The underlying frictional mechanism is discussed on the basis of water transport from bulk to surface and a previously proposed "repulsion-adsorption" model.
authors.affiliation: Department of Chemical & Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Kozbial
authors.affiliation: Department of Chemical & Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address: lel55@pitt.edu.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
mesh_terms: D000388:Air; D002351:Carrageenan / Q000737:chemistry*; D019245:Compressive Strength; D003432:Cross-Linking Reagents / Q000737:chemistry; D055119:Elastic Modulus; D017276:Friction; D006801:Humans; D020100:Hydrogels / Q000737:chemistry*; D008153:Lubrication; D011134:Polysaccharides / Q000032:analysis; D011312:Pressure; D014867:Water / Q000737:chemistry*
chemical_list: D003432:Cross-Linking Reagents; D020100:Hydrogels; D011134:Polysaccharides; D014867:Water; D002351:Carrageenan
keywords: Adsorption; Cross-linking; Friction; Hydrogel; Joint replacement; Mechanical properties