Flow Activation Energy Estimation by Thermo-Rheological Method

Abstract

Polymer and many other flows exhibit non-Newtonian rheological behavior. For some materials, the thermal dependence of viscosity is also essential to be established. It can be described by considering an activation energy, estimated by using the viscosity measurements at different temperatures. Nevertheless, the test temperatures must be reliable and accurate. An annular measuring device (TRAC: Thermo-Rheo Annular Cell) is previously proposed for highly robust temperature measurement and viscosity identification by inverse method, which exploits the viscous dissipation in the flow. This work explains how critical viscosity points, identified thanks to the TRAC, can be used to estimate the activation energy with different approaches involving the principle of time-temperature superposition. Thanks to the thermal characteristics of the annular flow, the thermal dependence of viscosity can also be estimated from direct temperature measurements to perform fast analysis, without using inverse method.