On the measurement of the high rate flow properties of organo-clay platelet filled polyamide 6 melts by capillary rheometer

The effects of test geometry on the capillary rheometer measurement of the high rate steady-state flow properties of an organo-clay platelet filled polyamide 6 (PA6) melt, and of the corresponding unfilled melt, were investigated. Attention was paid to the die diameter effects in tests carried out by a capillary rheometer equipped with cylindrical dies.
The results obtained by tests performed with dies of two different diameters and various length-to-diameter ratios demonstrated that the presence of organo-clay platelets in the nano-filled PA6 melt makes both the shear viscosity and the die entrance pressure losses highly dependent on the die diameter. The results are discussed on the basis of: 1. the influence of the flow channel geometry on the alignment of the highly anisotropic organo-clay platelets; 2. the propensity of PA6 chains to undergo chemical processes during the capillary rheometer tests.