Determination of the relaxation time spectrum from dynamic moduli using an edge preserving regularization method

Abstract

For the numerical determination of a continuous relaxation time spectrum from rheological data so-called regularization methods are necessary. The regularization method based on Tikhonov regularization and commonly used in rheology assumes the relaxation time spectrum to be smooth. Accordingly, this method is not able to properly resolve spectra containing edges or at least large curvatures as proposed in the literature. In order to reconstruct such spectra a novel edge preserving regularization (EPR) method was developed which extends the properties of the commonly used method. In order to demonstrate the efficiency of EPR it is compared with the commonly used regularization method by means of simulated and experimental data. This reveals that EPR is able to prove whether or not the theoretically predicted edge containing spectra for high-molecular-weight, monodisperse polymers are compatible with experimental data.