Relationship between constant strain rate and stress relaxation behavior of polypropylene

A new method based on variable transformation is proposed for the estimation of the constant strain rate tensile test by using a previously introduced concept of viscoelastic response given to the real relaxation stimulus. The time range of the “good” fitting is 2.5 to 3 times larger than the best results achieved using linear viscoelastic approximations. The theoretical background of the method was elucidated as well.