Incorporation of kaolin fillers into an epoxy/polyamidoamine matrix for coatings

The toughening of epoxy resins with the addition of organic or inorganic compounds is of great interest nowadays, considering their large scale of applications. The present work reports the results of the incorporation of two kaolin samples of different particle sizes into a polymeric base containing diglycidyl ether of bisphenol A (DGEBA) epoxy resin with polyamidoamine as hardener. A general review of the influence of fillers, especially clay ones, on epoxy matrices has been made. A prior surface treatment of the kaolin particles with anionic and cationic agents, sodium polyacrylate (Na-PAA) and dimethyldioctadecylammonium chloride (DOCA), respectively, helped to improve their dispersion into the matrix. Fourier transform infrared (FTIR), TGA, Zeta potential and surface energy measurements were conducted in order to assess the effectiveness of surface treatments. Microstructural observations and image analysis were also well suited to analyse particle dispersion and size distribution into the polymeric matrix. Microhardness tests realised on epoxy/polyamidoamine/kaolin systems allowed the study of the influence of particles pigment volume concentrations (PVC) on their behaviour.