Study on the Microscopic Network Model of PVA Hydrogel Based on the Tensile Behavior

Hydrogel is an emerging material widely used in the biological field. The tensile properties of hydrogel mainly depend on its polymer network, but due to the complex microstructure of the network, some properties of the hydrogel have yet to be quantitatively analyzed. In this article, we built a three-dimensional random fiber network to characterize the microstructure of a hydrogel. The fibers were simplified as elastic beams, and the cross-links were regarded as “hinges.” Combined with the macroscopic experimental results, the influence of the change of fiber length and the relationship between the polymer content and the cross-link density were studied. The model was verified by the quasi-static tensile test results of real PVA hydrogel materials with different fiber contents. The results show that the model can well match the tensile stress–strain curve and tensile strength of the PVA hydrogels with different fiber contents. The change in microstructure of the fiber network induces nonlinear behaviors, and although the cross-link number increases with the increase in polymer content, the cross-link density (per unit PVA chain length) of the PVA hydrogel slightly decreases as the content increases.