BS ISO 6721-8:2019

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.

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 0,5MHz to 5MHz. The method is suitable for measuring materials with storage moduli in the range 0,01GPa to 200GPa and with loss factors below0,1 at around 1MHz. 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 50mm×20mm×5mm, 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.