Fourier transform mechanical spectroscopy

A powerful new experimental method of determining the dynamic mechanical behaviour of viscoelastic materials is described. The method, Fourier transform mechanical spectroscopy (FTMS), consists of superposing and deconvoluting discrete Fourier transforms obtained from a single stress relaxation experiment using a novel sampling scheme. The theory of the sampling scheme and the superposition of the transforms is described elsewhere. In this paper the authors present the results of using the new method on Nylon over the frequency range 5*10 -4 to 20 Hz and temperatures from 25 to 110 degrees C. There is good agreement between the values of storage and loss moduli, obtained by means of the transform method, and those obtained by conventional means. An activation energy of 143 kcal mol -1 is obtained for the relaxation in this temperature range. The new method has considerable potential for the rapid determination of the mechanical properties of novel polymers and composites.