“…For the pure shear flow, the function f ( I |D| , II D , III D ) becomes equal to 1 and thus, the viscosity becomes a function of second invariant of deformation rate tensor D (IID=sans-serifγ˙2) only. In the pure uniaxial extensional flow, where I|D|= 2trueε˙, IID=3sans-serifε˙2, and IIID=sans-serifε˙3/4, the function f ( I |D| , II D , III D ) becomes nonzero and model becomes capable of representing steady-state extensional flows for different polymer melts [69,70,71,72,73,74].…”