Abstract: An accurate determination of the complex dynamic Young's modulus of a viscoelastic material, in a broad frequency range, is presented in this paper. Curves of Young's modulus of the tested material (a mixture of polypropylene and calcium carbonate), at different temperatures, are experimentally obtained by means of a laser sensor. The experimental curves are then gathered into a unique master curve, by applying the reduced variables method and a causality check on the curves. The master curve represents the Young's modulus of the viscoelastic material over a much broader frequency range, with respect to the range of a single experimental curve.