Preparation and characterization of nanocomposite uralkyd varnishes for a wood substrate

Three types of commercially modified montmorillonites (mMMT) have been tested as nanofillers in solventborne uralkyd coating compositions. The mMMT was introduced in the amount of 0.5 wt part into a coating system based on a soya oil fatty acid and isophorone diisocyanate (100 wt parts), applied onto a wood substrate, and oxidatively cured at room temperature for 14 days. An incorporation of organophilized montmorillonite into a coating composition significantly affects its viscosity (mMMT with a higher gallery space value increases that parameter) and slightly reduces the hardness of a dry coat. Moreover, a clay nanofiller increases glass transition temperature, abrasion resistance, elasticity, and impact resistance as well as barrier properties (measured using a conventional gravimetric method and an electrochemical impedance spectroscopic test) of a cured varnish. In the case of chemical resistance to acetone, lower blistering of modified coats was found.