Influence of molecular weight of hyaluronic acid on its viscosity was investigated through cone-plate viscometer. Water solution of hyaluronic acid had non-Newtonian flow, and the higher molecular mass showed higher viscosity. Lubricating ablility of hyaluronic acid at start-up motion was investigated by using a reciprocating friction tester, in which polyvinyl formal cylindrical surface slid on glass plate. High molecular mass of hyaluronic acid had an excellent film formation property in boundary lubrication mode at start-up, even if static loading duration was applied for invalid state of squeeze film.
