Frequency‐temperature superposition in polymer damping behavior

Abstract

The problem of determining optimum shift factors for frequency‐temperature dependence of polymeric material complex modulus properties has not been fully resolved even half a century after the pioneering work of Williams, Landel, and Ferry. The question of what form, such as the WLF (Williams, Landel, Ferry) equation or the Arrhenius equation, best depends on both the material and th& quality of the test data. In most cases, the data scatter is sufficient to prevent a definitive choice. These issues will be discussed with reference to available test data for several polymeric materials, obtained by various measurement techniques. It will be shown that the least ambiguous shift factor estimates are obtained when data scatter is as low as possible, and the frequency range of data at each temperature is as wide as possible, as would be expected. It will also be shown that differences arising from the use of different shift factor equations are not sufficient for most engineering applications.