Enhancement of epoxy based nanocomposite performance by the chemical modifications of bentonite

ROMINA OLLIER; MARCELA ELISABETH PENOFF; MATÍAS LANFRANCONI; VERA ALVAREZ

Sitges

Simposio; Third International Symposium Frontiers in Polymer Science; 2013

Epoxy resins have been widely used in several industrial applications, such as coatings, adhesives, laminates, composites and construction materials because of their elevated thermal, mechanical, and electrical properties. However, epoxies are brittle and they tend to absorb significant amounts of water when exposed to humid conditions, which has detrimental effects on the composite performance. To improve this, they may be reinforced with fillers. Clay minerals have been used to improve thermal, mechanical and barrier properties of epoxy resins. In fact, there is a great challenge for industrial application of epoxy-clay nanocomposites with enhanced properties due to their cost, lightness and improved properties. It is well known that the enhancement in the nanocomposite properties strongly depends on the level of clay dispersion in the polymer matrix (intercalation, exfoliation). For this purpose, the clays are organically modified through ion exchange reactions to facilitate the intercalation of polymers into the interlayer galleries and therefore facilitate the formation of an exfoliated nanocomposite. Many researches have been working on nanocomposites based on epoxy/ammonium modified clays; however, there are few publications based on the optimization of clay modification with phosphonium salts or other organic modifiers which can react with epoxy matrix and the subsequent preparation of nanocomposites. In this work, nanocomposites of epoxy-amine matrix with different organically modified bentonites and several clay contents (1, 3 and 5 wt. %) were prepared and their properties were investigated. Neat bentonite was modified with organophilic intercalating agents, including ammonium and phosphonium salts, as well as silane cations with reactive epoxy groups. All the modifications were optimized and further analyzed. Then, the structure of nanocomposites was investigated to evaluate the compatibility of the epoxy resin with different used clays by X-Ray Diffraction, the thermal and mechanical properties and water absorption degree of nanocomposites with different clay contents were also investigated.