Creep in macromolecular solutions according to rigid dumbbell kinetic theory

The creep experiment is analyzed using the rigid-dumbbell suspension model. It is found that the equilibrium shear compliance J _e is given by $$J_e = frac{{theta _0 }}{{2eta _0^2 }} + O(kappa _infty ^2 )$$ where η₀ and θ₀ are the viscosity and primary normal stress functions at zero-shear rate, and κ _∞ is the velocity gradient for large time. It is found that, to the lowest level of approximation, τ _yy ?τ _zz and τ _xx ?τ _yy have the same sign during the creep experiment.