An Essential Issue Not to be Ignored in Applying the Viscoelastic Mechanical Models of Polymers

The stress relaxation is one of the mechanical relaxation phenomena,which reflects the dependence of mechanical behavior of polymers upon time.An essential issue is not to be ignored in applying the viscoelastic mechanical models to simulate stress relaxation phenomena of linear polymers.The stress would not be a constant and declines with time,when keeping strain constant.The nature of mechanical relaxation and viscoelasticity of polymers was discussed in this paper.