Influence of layered structure on friction property of hydrogel

Abstract

Articular cartilage is an excellent bearing material for articular joint with extremely low friction. Cartilage has a specific hierarchical structure with lower elastic modulus on upper layer, and that may contribute to the lubricating function of cartilage. In this study, poly(vinyl alcohol) hydrogels with layered structure prepared by cast-drying method were used as cartilage model material and the influence of layered structure on friction property was investigated. Stiffness was obtained by indentation test, and friction coefficient was measured in reciprocating friction test with a friction pair of hydrogel sheet and glass ball. The results indicated the hydrogels that have thin and soft upper layer on harder layer showed higher stiffness and lower friction. The thinner the soft upper layer, the more the deformation of upper layer is constrained by hard lower layer. This may contribute to suppressing squeeze-out of interstitial water and maintaining biphasic lubrication function at higher level.