Thixotropy, nonmonotonic stress relaxation, and the second law of thermodynamics

Many thixo-viscoelastic materials have been reported to undergo enhancement in elastic modulus with time and decrease the same under application of deformation field. Incorporation this feature a viscoelastic structural kinetic model has an apparent possibility violating second law thermodynamics. Furthermore, related experimental observation, stress non-monotonic change as function constant strain. We analyze both these scenarios through that shows aging but undergoes rejuvenation only due viscous rate observe such formalism does not violate law. Interestingly, proposed simple predicts observation relaxation very well.