Rheological and tribological behavior of polyacrylamide-base solutions for artificial synovial fluid

This paper presents tribological and rheological analysis results of artificial synovial fluid base solutions. Special attention was paid to polyacrylamide preparations with different molecular weights and concentrations. Tribological tests were conducted using the Al2O3-CoCrMo friction pair in the presence of investigated lubricants. Confocal microscopy was used to analyze and assess of volume, depth, and width of wear traces. Moreover, the viscosity and viscoelasticity tests of analyzed solutions were carried out. The rheological measurements were focused on the oscillatory tests, which allowed us to determine the elasticity modulus (G') and viscosity (G″). Viscoelastic nature of the tested preparations depends on the strain rate. It has been shown that elastic properties dominate at higher frequencies. The molecular weight of the polymer has a particular influence on these properties. The most promising results were obtained for 6% and 8 % high molecular weight polyacrylamide compositions. However, all tested polyacrylamide solutions show better rheological and tribological characteristics than commercial preparation based on hyaluronic acid.