Accordingly, in the process of the multi-parametric fitting of experimental data set it is enough to estimate the unknown Weibull moduli mα, mβ, mγ a mf, which quantify the width of the secondary bonds failure distribution corresponding to the level of crystallinity (mα), the width of the secondary bond strengths distribution in the given temperature intervals (mβ, mγ), and the width of secondary bond strength distribution corresponding to the TPU degree of cross-linking (mf) [14].