Wednesday  |  Carnegie III  |  11:50 AM–12:10 PM

#13790, Does the Magnitude of the Loss Tangent Change with Deformation Mode?

The quantity of the loss tangent is of great importance to the mechanical behaviour of polymers. By definition, it describes the portion of mechanical energy transformed to heat in a mechanical deformation cycle, which in turn probes into molecular relaxation mechanisms. In practice, the loss tangent is defined in experiments like Dynamic Mechanical Analysis (DMA) as the ratio between the loss modulus and the storage modulus, or the tangent of the phase angle between the stimulus (stress) and response (strain). The loss tangent is often treated as a universal quantity, which is fundamentally linked to losses in the material. However, the values measured in practice may not be as universal. In particular, it has been observed before that there is some discrepancy between the values of loss tangent peaks, for the same material under different modes of deformation. This extended abstract presents our latest measurements of loss tangent on the same material, under different deformation modes. Some discussion is included regarding the reasons for any differences between deformation modes.

Malvina Constantinou   University of Cambridge
David Williamson   University of Cambridge