RELAXATION-TIME SPECTRA OF LINEAR AND CROSS-LINKED POLYMERS

In this work, an attempt has been made to define a unique relaxation t ime spectrum for different types of polymeric materials. Empirical mod els for the relaxation spectrum, proposed for linear flexible polymers in the literature, have been used. A systematic determination of the parameters defining the relaxation time spectrum has been made from dy namic mechanical data. It has been shown that the resulted expression for the relaxation modulus could then be used to calculate the stress response of the materials to various deformations. The strain rate dep endence of yield behavior could also be predicted. (C) 1998 John Wiley & Sons, Inc.