Properties of layered double hydroxide micro- and nanocomposites

Carbonate and stearate intercalated layered double hydroxides were used as fillers to prepare polymer micro- and nanocomposites, respectively. The stearate modified starting material was bilayer-intercalated clay. During melt compounding excess stearates were released and the clay reverted to a monolayer-intercalated form. The exuded stearate acted as a lubricant lowering the melt viscosity of poly(ethylene-co-vinyl acetate) and linear low density polyethylene matrices. Strong hydrogen bond interactions between the chains of poly(ethylene-co-vinyl alcohol) and the clay platelet surfaces overwhelmed the lubrication effect and caused an increase in the melt viscosity of this matrix. The notched Charpy impact strength of this composite is almost double that of the neat polymer. It appears that this can be attributed to the ability of the highly dispersed and randomly oriented nano-sized clay platelets to promote extensive internal micro-cavitation during impact loading. The creation of a large internal surface area provided the requisite energy dissipation mechanism. (C) 2012 Elsevier Ltd. All rights reserved.