A study of the transient shear flow behavior of the incompressible and isothermal thermoplastic polymer materials

In this article, a feasible mathematical method was proposed to describe the instantaneous shear flow behavior of the incompressible and isothermal thermoplastic materials. Based on the molecular kinetics, thermodynamics, and continuum mechanics method, a viscoelastic model was presented about the intricate rheological phenomena of polymer macromolecules, which is simplified as the generalized Newton’s law. The rheological experiments were carried out with the isotactic polypropylene material. The analysis of variance method was performed to determine the fitness of the model. By comparing with the Ostwald–de Waele power law model and Cross model, the theoretical model was studied. The experimental results reveal that the theoretical model is more accurate than the Ostwald–de Waele power law model and shows a roughly equivalent fitness with the Cross model, which indicates that the theoretical model is effective and robust. Moreover, the results of this study may have potential industrial applications and benefit the users of certain plastic components.