Describe what viscoelastic behavior means

This refers to the mechanical properties of the materials tested by means of a stress stimulus or deformation. The mechanical behavior of a material will depend on its viscosity / elasticity characteristics. Depending on the response to mechanical stimulus, the material may be classified as elastic or viscous. For a perfectly elastic or Hookian solid the deformation is proportional to the applied stress. A viscous material obeys Newton's law, which states that stress and shear rate are related through an intrinsic characteristic that is viscosity.

However, there are materials that correspond to both properties. Polymers have an intermediate mechanical behavior to elastic and viscous, being called viscoelastic. The elastic and viscous contribution to the mechanical behavior of the polymer depends on the temperature and time scale of the experiment.