固液二層性材料の摩擦界面における水分流出入と摩擦特性の関連

抄録

Biphasic lubrication is one of the factors that enable articular cartilage to achieve excellent lubrication. In order to elucidate the biphasic lubrication mechanism, it is important to understand the behavior of water inflow/outflow at the friction interface. In this study, poly(vinyl alcohol) cast-drying gel (CD gel) which has water content and permeability similar to articular cartilage, was used as a model material for cartilage. And then, relationship between water inflow/outflow at the friction interface and friction property of biphasic material was investigated. The internal water in CD gel was replaced by heavy water and it was used as a tracer of water squeezed out from CD gel. The unidirectional friction test was conducted by using rheometer, and amount of water squeezed out from CD gel during the test was estimated by measuring infra-red spectrum of heavy water in the lubricant. The results indicated that the squeezing out of water from CD gel was suppressed under higher sliding speed condition. It is considered that generation of hydrodynamic pressure between the frictional surfaces under higher sliding speed condition suppressed the squeezing out of water from CD gel, and it contributed to maintaining biphasic lubrication function at higher level.