Tansformation Range Viscosity Measurements Using a Thermomechanical Analyzer

A commercial thermomechanical analyzer has been adapted to determine the transformation range viscosities of very small samples using a beam-bending configuration. Three viscosity standards—NBS-710, NBS-711, and NBS-717—have been used to determine the accuracy of this technique over a wide range of temperatures. The method yielded excellent results that were independent of sample size and heating rate. The largest deviation from National Bureau of Standards data was 3.8°C at 10¹⁰ Pa's for one sample of NBS-711; the average deviation at 10¹⁰ Pa's was approximately 2°C for all samples studied. In all cases, the activation energy for viscous flow was in excellent agreement with that calculated from National Bureau of Standards data.