Computational Study of Cross-Link and Entanglement Contributions to the Elastic Properties of Model PDMS Networks

We built randomly cross-linked model PDMS networks and used Molecular Dynamics Methods to obtain stress-strain curves.Mooney-Rivlin (MR) analysis was used to estimate the shear moduli.We applied Primitive Path analysis (PPA) and its variation, Phantom Primitive Path analysis (3PA), to estimate the entanglement and the cross-link moduli, respectively.The MR moduli estimates are in good agreement with the sum of the entanglement and the cross-link moduli, and we observe that the stress-strain data collapse to a universal form when reduced with the PPA and 3PA moduli.We studied how the MR parameters C 1 , C 2 vary from cross-link to entanglement dominated networks.For the latter, we observed a 40%, 60% contribution of 2 C 1 , 2 C 2 to the shear modulus, respectively.Finally, we fitted several models to the data.While all fits are good, the estimates for the entanglement and the cross-link moduli vary significantly when compared to our PPA and 3PA