Overcoming the difficulty in performing large step-strain experiments: A first reliable comparison with Doi-Edwards tube model

Large step shear has been a popular way to interrogate nonlinear viscoelastic responses of polymeric materials. In absence of any severe interfacial failure, the experimental data [1] were found to agree with the Doi-Edwards model of entangled chains. A separate set of experimental studies [2-4] produced strain-softening and showed disagreement with the D-E model. We have successfully prevented interfacial breakdown for the first time to show that the strain-softening is an interfacial artifact [5] and that the stress relaxation behavior of entangled melts and solutions can be reliably depicted experimentally and accounted for within the D-E model. \newline [1] Osaki, K. \textit{et al Macromolecules} \textbf{15}, 1068 (1982). \newline [2] Osaki, K.; Kurata, M. \textit{Macromolecules }\textbf{13}, 671 (1980). \newline [3] Vrentas, C. M.; Graessley, W. W. \textit{J. Rheol. }\textbf{26}, 359 (1982). \newline [4] Osaki, K. \textit{Rheol. Acta }\textbf{32}, 429 (1993). \newline [5] Venerus, D. \textit{J. Rheol. }\textbf{49}, 277 (2005).