Young's modulus measures a material's stiffness under both tension and compression, assuming linear elasticity. Compressive modulus, however, specifically measures stiffness during compression, making it more relevant for hydrogels, which often experience compressive forces. While Young's modulus can be derived from both tensile and compressive tests, compressive modulus is often preferred for hydrogels due to their nonlinear behavior and the prevalence of compressive loading in their applications. The choice between the two depends on the specific hydrogel, its intended use, and the experimental setup. For example, consider a hydrogel used in tissue engineering. If the hydrogel is implanted and primarily experiences compressive forces from surrounding tissues, compressive modulus would be a more relevant measure of its mechanical properties. This modulus would provide information about the hydrogel's ability to withstand these compressive forces and its potential to support cell growth and tissue regeneration. On the other hand, if the hydrogel is used in a device that involves both tensile and compressive forces, Young's modulus could be a more appropriate measure, as it considers the material's response to both types of stress.

Clearly explained! Thank you very much.