NBN ISO 6721-8:2021

This document describes an ultrasonic wave propagation method for determining the storage
components of the longitudinal complex modulus L* and the shear complex modulus G* of polymers
at discrete frequencies typically in the range 0,5 MHz to 5 MHz. The method is suitable for measuring
materials with storage moduli in the range 0,01 GPa to 200 GPa and with loss factors below 0,1 at
around 1 MHz. With materials that have a higher loss, significant errors in velocity measurement are
introduced through waveform distortion and can only be reduced using procedures that are outside
the scope of this document.
The method allows measurements to be made on small specimens, typically 50 mm × 20 mm × 5 mm,
or small regions of larger specimens or sheets. It is therefore possible to obtain information on the
homogeneity or anisotropy (see 10.5) of modulus in a specimen.