In this paper, a constitutive modeling framework was introduced to characterize the time-
dependent behavior in poly (lactic acid) reinforced by cellulose nanocrystals (CNCs). The
mechanical properties of PLA and its corresponding nanocomposites were analyzed at
three different extension rates (1, 5, 10 mm/min) using a stress relaxation test. Six
hyperelastic strain energy functions were employed to describe the instantaneous
mechanical behavior. The deviatoric and volumetric material constants were verified using …