Necar Merah
King Fahd University of Petroleum and Minerals, Saudi Arabia
Title: Improving water barrier and mechanical properties of epoxy with nanoclays
Biography
Biography: Necar Merah
Abstract
Statement of the Problem: Epoxy resins have an attractive combination of stiffness, strength, high heat distortion temperature, creep resistance, thermal, and environmental stability. This makes them one of the most applied thermoset polymers for fiber reinforced structures and anticorrosion coatings. However, epoxies’ affinity to water results in moisture uptake that degrades the functional, structural, and mechanical properties of epoxy-based composites and coatings. Absorbed liquid molecules act as efficient plasticizers for cured epoxy systems thereby reducing strength, stiffness, and glass transition temperatures. Several researchers have shown that proper mixing of clay nanocomposites with epoxy reduces its water uptake and helps improve its mechanical, thermal and physical properties. The purpose of this work is to show what optimum parameters can lead to proper clay dispersion and distribution of nanoclays in epoxy matrix. Methodology: Two mixing techniques, high shear mixing (HSM) and ultra-sonication, were used, at different mixing speeds and times, to disperse different clay loadings (1-10wt%) in diglycidyl ether of bisphenol A (DGEBA) epoxy matrix. Four types of organically-modified montmorillonite clays are investigated, namely; monomers: I.30E, I.28E, and Cloisites C10A, and C15A. Findings: The results showed that optimal clay dispersion was obtained with 1.0wt% to 2.0wt% of I.30E and C10A clays, using HSM at the optimum speed and mixing time of 6000 rpm and 60 min, respectively. These, with a degassing temperature, around 100ËšC lead to the synthesis of nanocomposites with a disorder-intercalated and exfoliated morphologies that reduced the diffusion constant of epoxy by more than 50% and maximum water uptake by more than 20%. Conclusion & Significance: The reduction in water uptake improved the glass transition temperature and the mechanical properties of the pristine polymer. These improvements are mainly due to the tortuosity effect, where water molecules have to move around clay layers during diffusion in nanocomposites.