What is ISO 6721-8 - Longitudinal and shear vibration of plastic about?
ISO 6721-8 is the eighth part of the ISO 6721 multi-series on dynamic mechanical properties of plastic. ISO 6721-8 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 ISO 6721-8.
Note: 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 of modulus in a specimen.
Who is ISO 6721-8 - Longitudinal and shear vibration of plastic for
Open preview (PDF)Plastics. Determination of dynamic mechanical properties - Longitudinal and shear vibration. Wave-propagation method