Development of epoxy/phosphonium modified bentonite nanocomposites

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

Puerto Iguazú

Congreso; 13º Congreso internacional en ciencia y tecnologia de metalurgia y materiales; 2013

Epoxy-based thermosetting polymer resins are widely used in several industrial applications because of their outstanding characteristics such as light weight, good chemical resistance and improved thermal and mechanical properties. However, epoxies are brittle and they show a natural tendency to absorb significant amounts of moisture when exposed to humid conditions. These factors have detrimental effects on the physical properties of epoxies and can therefore greatly compromise the materials performance. A novel alternative to overcome these problems is the reinforcement with fillers. Clays can effectively enhance thermal, mechanical and barrier properties of epoxy resins even at low loadings. It is well known that the enhancement in the nanocomposite properties strongly depends on the level of clay dispersion in the polymer matrix. Two different morphological structures are mainly achievable: nanocomposites with either intercalated or exfoliated clay mineral. Clays can be organically modified through ion exchange reactions to facilitate the intercalation of polymers into the interlayer galleries and therefore facilitate the formation of an exfoliated structure. Many researchers have been working on nanocomposites based on epoxy/ammonium modified clays; however, there are few publications regarding the optimization of clay modification with phosphonium and the subsequent preparation of epoxy based nanocomposites. In this work, epoxy-amine based nanocomposites with different loadings (1 to 5 wt. %) of an organically modified bentonite were prepared and their properties were investigated. First, the neat bentonite was exchanged with an alkyl-phosphonium salt and different reaction conditions were studied. All the modifications were optimized and further analyzed. The structure of epoxy/organoclay nanocomposites was investigated by X-Ray Diffraction in order to assess the epoxy resin - organoclay compatibility; the thermal and mechanical properties, together with the water uptake of nanocomposites with different clay contents, were also investigated