Rheological behaviour of acrylate/montmorillonite nanocomposite latexes and their application in leather finishing as binders

The paper describes the theological behaviour of nanocomposite latexes based on butylacrylate-co-methylmethacrylate-co-acrylamide terpolymers including various commercial nanoclays obtained via in situ emulsion polymerization. Rotational, oscillatory, emulsion stability and thixotropy tests (recovery) were performed to evaluate the influence of clay incorporation, type of clay and also emulsifier content in the composition of these nanomaterials. It was observed that the viscosities of the nanocomposite latexes were increased by clay incorporation at low shear rates, while a shear thinning effect was observed at higher shear rates. Oscillatory tests indicated a dominant elastic behaviour and high physical stabilities for all the nanocomposites. The hydrophobic character of the clay and emulsifier content also influenced the viscosity and dynamic modulus of the emulsions. The nanocomposite latexes were tested for leather finishing as polymeric binders. Results showed that the finish performance of the leather surfaces was improved by clay incorporation. It was also concluded that for coating applications it is important to find a balance between the compatibility of the nanoclay type with the polymer and the emulsifier amount necessary for emulsion stabilization which both influence the rheology and the final performance of the coatings. (C) 2010 Elsevier B.V. All rights reserved