What is a characteristic feature of viscoelastic materials?

Viscoelastic materials are unique in their ability to display both viscous and elastic behaviors when subjected to stress. This dual characteristic means that they can deform under load like a viscous liquid and return to their original shape upon the removal of the load, similar to elastic solids.

The viscous behavior relates to the time-dependent strain that occurs when a viscoelastic material is deformed, leading to a gradual change in shape under constant stress, while the elastic response allows for immediate recoverability after the applied stress is removed. This combination is crucial for applications where materials need to absorb energy, dissipate stress, and provide cushioning, making viscoelasticity essential in products like rubber, polymer coatings, and various biological tissues.

Other characteristics provided in the options do not accurately describe the fundamental nature of viscoelastic materials. For instance, the assertion about easy fracturing under stress or significant shrinking upon heating does not apply universally to all viscoelastic materials. Instead, many viscoelastic materials maintain integrity and undergo more complex deformation mechanisms under stress, highlighting why the combination of viscous and elastic characteristics is the defining feature of viscoelasticity.