Transiently trapped entanglements in model polymer networks.

R. H. ACOSTA; G.A. MONTI; M.A. VILLAR; E.M. VALLÉS; D. A. VEGA

MACROMOLECULES

AMER CHEMICAL SOC

Año: 2009 vol. 42 p. 4674 - 4680

0024-9297

We study the effect of trapped entanglements in model silicone polymer networks through the residual dipolar couplings obtained by double quantum nuclear magnetic resonance (DQ NMR). Model polymer networks containing low contents of entangled linear pendant polymers of different molecular weights were analyzed. The dependence of the residual dipolar coupling with the functionality of the cross-linkers is in good agreement with the predictions of the theory of rubber elasticity. A linear correlation was found between DQ NMR experiments and a theoretical relaxational model that includes the mean field description of the network structure and the Pearson-Helfand free energy potential for arm retraction.