Estimation of stresses required for exfoliation of clay particles in polymer nanocomposites

Abstract

AbstractThe dispersion of clay in a polymer matrix is influenced by two factors: the choice of organic treatment for the clay and the processing or mixing method. Maximum benefits are achieved when the platelets are well dispersed or exfoliated. Exfoliated nanocomposites are formed when the individual clay layers break off the agglomerated particles or tactoids and are either randomly dispersed in the polymer (a disordered nanocomposite) or left in an ordered array. It is suggested that size reduction of clay particles and platelet delamination occur by erosion or surface peeling. A model based on the classical theories of interparticle interactions was formulated for the exfoliation of the clay platelets in a polymer matrix. The model involves the estimation of the binding energy and the adhesive force between the platelets in a clay particle, which indicate the forces required for breaking apart or delamination of clay particles. Then, the shear force required for breakup or delamination of the tactoids is estimated and compared to the hydrodynamic shear forces available during processing. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers