Derivation of the mormal stress coefficient from the Ree-eyring equation of non-newtonian flow

Abstract

In this study, we have proposed a theory which was derived from the Ree-Eyring theory of non-Newtonian flow, and predicted the normal stress coefficient. The flow parameteric values appearing in our viscosity equation were obtained by applying our theory to experimental values of viscosity for various systems. By using the parameteric values of $\beta$ and $X_i\beta_i/\alpha_i$(i = 1 or 2) the values of $\eta$ were recalculated from our theoretical equation. The theoretical values of $\eta$ were compared with experiment for various viscoelastic materials. We found that the agreement between theory and experiment is excellent. By using the parameteric values, the normal stress coefficients ratio $\theta/\theta_o$ were also calculated from our normal stress coefficient equation. For viscoelastic materials investigated in this study, the agreement of the theory with experiment was satisfactory. Viscoelastic materials investigated in this study are listed below: 7.0\% aluminum soap solution, post mortem synovial fluid, 2.5wt polystyrene, 4.0wt\% polystrene, 5.0wt\% polystyrene, 0.75wt\% polyacrylamide, 1.5wt\% polyacrylamide, 2.0wt\% polyisobutylene, 5.0wt\% polyisobutylene, HDPE melt, LDPE melt, polypropylene melt and phenoxy-A melt.