Comparing flow characteristics of viscoelastic liquids in long and short capillaries (entrance effects)

This study is devoted to the analysis of physical meaning difference in results viscosity measurements obtained by using two-capillary method—carrying on same flow rate through two circular parallel capillaries different lengths but diameter. Furthermore, there other approach for short determination a value, known as “elongational viscosity,” based concept domination extension at convergent along inlet capillary. The theory this method dates back publication Cogswell. However, it was shown that inadequate polymeric liquids demonstrate time-dependence effects. In study, we present experimental data melts polyethylenes molecular weights and their mixtures. capillary viscometry are accompanied measuring viscoelastic properties. showed cannot give chance estimate viscosity” elastic liquids. between losses long treated terms “end correction,” which determined Weissenberg number. Hence, elasticity main parameter responsible additional