Entanglements in amorphous polymer networks

This paper consists of two parts. In the first part, the strain dependence of entanglements or constraints acting along the contour of a Gaussian chain is derived. The functional form of the elastic free energy resulting from constraints along the chain contour is identical to that obtained in the Flory constrained junction model. In the second part, the effective number of constraints acting along the contour of a chain is discussed. The choice of this number results from postulates imposed by various authors and cannot be derived by rigorous theory. The paper compares the predictions based on these assumptions with experimental data from model networks.