A non-linear viscoelastic model with structure-dependent relaxation times: I. Basic formulation

A non-linear constitutive equation for polymer melts and concentrated solutions is presented. Based on known results of network theories, the model contains a distinctive feature: that of letting the relaxation times depend upon the existing structure.The model extends the constitutive equation of linear viscoelasticity to the non-linear region in a well-defined way, with the uncertainty of just a single adjustable parameter.Predictions of the model for common cases of non-linear response are derived and discussed.