New polymeric nanocomposites for improving the protective and consolidating efficiency of tuff stone

Nanocomposite systems based on the commercial polymer Fluormet CP and different amounts of the Cloisite 30B organoclay (1, 2 and 4 wt%) were tested as protective and consolidating agents for the Neapolitan yellow tuff. The conservation and restoration efficiency of these treatments was evaluated through physical investigations (water capillary absorption, permeability to water vapor, abrasion resistance and mechanical properties) and aesthetic-morphological observations (colorimetric measurements and SEM analyses). The results have evidenced that the nano-scale dispersion of low amounts of Cloisite 30B into the polymeric matrix enhances the consolidating and protective action of Fluormet CP. In fact, yellow tuff stone treated with the nanocomposite systems exhibits a more marked reduction in water absorption and water vapor permeability as well as improved mechanical and abrasion resistance with respect to stone treated with the neat Fluormet CP. Furthermore the applications of these nanocomposites systems do not alter the chromatic appearance of the stone substrate and not considerably modify the reversibility properties of the original polymeric matrix.