Friction Properties of Laminated Composite Materials of Alpha-Tricalcium Phosphate–Filled Poly (Vinyl Alcohol) Hydrogels

The aim of this study was to examine the mechanical characteristics of a polyvinyl alcohol hydrogel (PVA-H) as a candidate material for artificial joint cartilage. In the study, PVA-H was filled with α-tricalcium phosphate (α-TCP) in order to improve its mechanical properties. In addition, laminated composite materials with 3 layers were prepared by laminating α-TCP–filled PVA-H and unfilled PVA-H. The samples were prepared with different numbers of repeated freeze–thaw cycles and several concentrations of α-TCP. Compression tests and friction tests were carried out to investigate the mechanical and friction properties of the PVA-H. The results of the tests showed that the compressive modulus and the friction coefficient of the α-TCP–filled PVA-H were higher than those of the unfilled PVA-H. Thus, α-TCP was found to be effective in reinforcing the PVA-H. In the friction tests, the friction coefficient of the laminated material was approximately equal to the values of the unfilled PVA-H. Furthermore, the compressive moduli of the laminated materials that underwent 5 and 7 freeze–thaw cycles improved to a level equal to that of the α-TCP–filled PVA-Hs. Therefore, the lamination of PVA-H made it possible to achieve both a low friction coefficient and high compressive strength.