Rheological Properties of Thermoplastic Polyurethane/Multi-Walled Carbon Nanotube Nanocomposites

Abstract

Carbon nanotubes offer the possibility of substantial improvements in the properties of polymer-based composites. However, adding carbon nanotubes increases the viscosity and makes the composites more difficult to process. Consequently, understanding the rheological behavior of nanocomposites is important from both the theoretical and industrial points of view. In the present work, rheological behavior of thermoplastic polyurethane filled with various amounts (1, 3 and 5 wt.%) of multi-walled carbon nanotubes was investigated by capillary rheometry. In this regard, the melt flow behavior of the nanocomposite was measured using a capillary rheometer with a die length-diameter ratio of 30:1, 20:1 and 10:1. In order to investigate the effect of temperature on viscosity, the tests were carried out in the temperature range of 180 to 210°C. The shear rate examined between 100 and 5000 s-1, cover the shear experienced during most polymer processing techniques. The Bagley and Weissenberg-Rabinowitsch correction was performed to determine the real viscosity of the nanocomposites; moreover, the Cross viscosity model coefficients were determined.