Influence of microstructural parameters on mechanical behavior of polymer gels

The swelling deformation behavior of polymer gels is often described in terms of the Flory-Rehner framework, in which the Flory-Rehner free energy function is based on the simplest affine network model, does not take entanglements into account. However, the real polymer networks have many chain entanglements. In this paper, a new hybrid free energy function composed of the Edwards-Vilgis slip-link model and the Flory-Huggins solution theory is presented for the prediction of the influence of chain entanglements on mechanical behavior of gels. The simulation results of mechanical behavior in free swelling, uniaxial extension, biaxial constraint and simple shear are presented. It is shown that in the nonentangled state, this new hybrid free energy function reduces to the Flory-Rehner free energy function; in the entangled state, the influence of entanglements on the mechanical behavior of gels is significant, the more entangled networks exhibit higher stress. (C) 2011 Elsevier Ltd. All rights reserved.