UV curable transparent urethane-acrylate/clay nanocomposite coating materials with thermal barrier property

Abstract

The incorporation of organically modified montmorillonite (MMT) as thermal barriers into an UV curable urethane-acrylate based resin system was attempted to prepare nanocomposite coating materials with improved thermal barrier property using a two-step solution mixing process. The prepared nanocomposite sols were deposited on glass substrates using a bar coating method, and cured under radiation. We explored the correlation between the mixing time in association with shear stress imposed on clay agglomerates, and the resulting nanostructured morphology including the degree of exfoliation and dispersion state of the clay in the prepared nanocomposites. The effects of the nanoclay loading level on the properties and morphology of the nanocomposites were also investigated. As a result, it was revealed that with an appropriate level of clay loading at 5 wt.% and shear stress, high degree of intercalation and exfoliation structure with homogeneous clay dispersion in the matrix could be achieved, and for the nanocomposite-coated glass, the thermal barrier performance was noticeably enhanced by 72% over that of non-coated glass, while exhibiting fairly good optical transparency with light transmittance over 80%. In addition, the thermal stability and dynamic mechanical properties of the nanocomposites were also improved. It can be anticipated that a novel method for preparing the UV curable nanocomposite coatings on glass, which is presented in this study, will be utilized to fabricate the thermally insulated transparent window system. (C) 2013 Elsevier B.V. All rights reserved.