Simulation and modeling of three-dimensional percolating structures: Case of a latex matrix reinforced by a network of cellulose fibers

The composite presented here, which is made of cellulose whiskers embedded into a latex matrix, shows quite surprising elastic properties due to the fact that a continuous skeleton of hard whiskers is formed with some tight interactions. The work shows that the classical homogenization techniques are not applicable here, in particular because those techniques do not make any difference whether or not tight interactions are considered. The percolation problem is investigated by means of numerical simulations to quantify the percolation threshold and the mechanical properties are obtained by means of the Percolation Theory and a simple Voigt model. Finally, a continuous description is proposed, using Cosserat Continua, where the material's behavior exhibits a length scale. Ail the elastic parameters associated with this description are determined by Finite Element simulations. An attempt is made to understand the physical meaning of this length scale. (C) 1997 Acta Metallurgica Inc.