Research on viscoelastic behavior and mechanism of hydrogel grafted with UHMWPE

Hydrogel has been extensively studied for use as articular cartilage. The static and dynamic viscoelasticity behaviors of hydrogel grafted with ultra-high-molecular-weight polyethylene (UHMWPE) were studied by finite-element method (FEM) and dynamic mechanical analysis in this article. The results show that creep deformation presents an exponential function with the pore fluid velocity of hydrogel material. During the first period of stress relaxation, the internal fluid pore pressure of hydrogel material is less than partial pressure, which leads to the increasing fluid exudation, and the stress relaxation rate changes quickly. With the loss of fluid, the pore pressure and partial pressure achieve balance. Then, finally, stress relaxation reaches relative equilibrium. The storage modulus of hydrogel material increases with the increasing frequency, and there is a logarithmic regression between them. With the decrease in liquid–solid ratio, the storage modulus declines, while the loss modulus first increases and then decreases. When the strain increases, both storage modulus and loss modulus show an upward trend.