USE OF RHEO-NMR T2 RELAXATION TIMES TO ESTIMATE TEMPERATURES IN A STANDARD NEWTONIAN OIL UNDER SHEAR FLOW

Abstract

Viscous heating is significant in materials processed at high shear rates. The objectives of this thesis were to a) determine how the NMR relaxation time T2 of a Newtonian standard changes with temperature; b) use the T2 measured under shear to estimate the temperature; and c) compare these estimates to those from a thermo-rheometric model (TRM). Experiments under static conditions in a Rheo-NMR mini-Couette system provided data successfully used to develop a function for the increase of T2 with temperature. Rheo-NMR T2 measurements were then conducted under shear rates from 2 to 1200 s-1. The function between temperature and T2 was applied to predict the temperatures under shear. The estimated temperatures increased at high shear rates but not at low shear rates, as estimated by the TRM. At high shear rates, the magnitudes of the temperatures estimated from both methods diverged, showing that the methods require further refinement.