Using the available correlations between the first normal stress coefficient, 0, and the shear viscosity function, and between the first normal stress difference, N1, and die swell (DS), it is possible to predict DS from experimental shear viscosity data. Poly(vinyl chloride) exhibits two distinct flow activation energies, corresponding to the development of a supermolecular flow and a true melt flow, respectively. As a result, in the low temperature range DS increases with temperature, whereas at higher temperatures the opposite effect is observed. It is possible to adapt the above methodology to include both behaviours. The predictions are experimentally assessed
Посилання на статтю:
Elasticity of poly(vinyl chloride) melts / J. A. Covas* and O. S. Carneiro // Polymer. – 1992. – Vol 33. – P. 4977-4982.