ABSTRACT
A new approach is proposed for the development of a constitutive equation that is appropriate only for unfilled elastomers. This new approach is based on the concepts of statistical mechanics, thermodynamics and the theory of rubber elasticity. The partition function, for a random walk of the chain of macromolecules can be written as a function of the Langevin function and the Helmohltz free energy is estimated. The development of the model is based on the maximum extensibility of the chain and the shear moduli which are the only parameters needed to be determined from experimental tests. These parameters can be easily determined only by looking at experimental data, and there is no need for doing nonlinear fitting, as other models require. The model allows treating the constrained junction and the tube model within the same transparent formalism as does not require any further approximations, and it is particularly suited for the analysis of simulation data for strained model polymer networks.
