Monte-Carlo simulations of the configurations of polymer chains in reinforced elastomers reveal extensive wrapping of the chains around particle clusters The resulting Increase in chain entanglement density leads to a 3 5 power law dependence of modulus on particle loading, in perfect agreement with experimental observation Our model also gives a consistent molecular explanation of the Payne effect and the associated energy dissipation in strained reinforced elastomers (C) 2010 Elsevier Ltd All rights reserved