Large amplitude oscillatory shear and Fourier-transform rheology for a high-density polyethylene: Experiments and numerical simulation

Rheological characterization of a high-density polyethylene is performed by means of measurements of the storage and loss moduli with a new viscometric device. Shear viscosity is deduced from both the Cox-Merz rule and capillary measurements. Subsequently, oscillatory experiments are performed in the nonlinear regime, with deformation amplitudes as high as 10. A multimode Giesekus model is selected to describe the rheological behavior of the melt, the parameters of which are successively identified on the basis of the linear properties and the shear viscosity. This model is subsequently used for the numerical simulation of large amplitude oscillatory flows. Fourier-transform rheology is applied to both experimental measurements and simulation results. A comparison is made on the basis of the value of the harmonics, the maximum amplitude of the stress signals, and the phase shift occurring between the applied deformation and the stress output signal. Good quantitative agreement is found between experiments and calculations, demonstrating the relevance of the present approach. (C) 2002 The Society of Rheology.