Abstract
A unifying stress–strain model for physical networks (polymer melts) and for permanent networks (rubbers) is presented. It is based on three assumptions: (1) the uncrossability condition of real chains can be modeled by the tube concept; (2) the tube diameter is a function of the average stretch; and (3) the tube volume is invariant with respect to deformation. The model predicts that stress–strain behavior of dry and swollen rubber networks is completely determined by four material constants: the equilibrium modulus G∞ of the bulk network; the critical entanglement modulus G*e, which is equivalent to the plateau modulus GN of the un‐crosslinked parent melt; a finite extensibility parameter α; and a solvent‐polymer interaction exponent β. Predictions are compared with experimental data in elongation, and agreement is excellent. The Mooney–Rivlin constant C2 of unswollen networks with high crosslink densities is limited to roughly GN/2, and the origin of the C2 term is shown to be due to nonaffine deformat...
Published Version
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