16 TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS EFFECT OF SHEARING ON DISPERSION, INTERCALATION/EXFOLIATION OF CLAY IN EPOXY Tri-Dung Ngo*, Van-Suong Hoa*, Minh-Tan Ton-That** * Department of Mechanical & Industrial Engineering, Concordia University, Montreal, Quebec, Canada, H3G 1M8, ** National Research Council Canada, Industrial Materials Institute, Boucherville, Quebec, Canada, J4B 6Y4 Keywords: nanoclay, epoxy, nanocomposites, mixing, shear, dispersion and mechanical properties. Abstract Nanocomposites from Shell EPON828 and Jeffamine D230 (D230) were prepared by different mixing methods which can generate different shear forces such as mechanical stirrer, microfluidizer and homogenizer. An organoclay Cloisite 30B (montmorillonite treated with a quaternary ammonium intercalant) was used. The quality of dispersion and intercalation/exfoliation was analyzed by XRD, FEGSEM and TEM. The tensile and compressive properties of the epoxy and epoxy nanocomposites (ENC) were also determined.The result indicates that well dispersed and well intercalated/exfoliated ENC is achieved with a non solvent assistance method. It is also found that with finer and more uniform dispersion of the clay in ENC achieved by this solvent free method the tensile strength is improved. 1 Introduction Processing parameters have important influence on the dispersion of clay in polymer. This in turn has effect on physical and mechanical properties of nanocomposites. Dispersion process parameters mainly include mixing temperature and time, speed and time of stirring, power of ultrasonic tooling, shearing forces etc. Direct mixing of organoclay and epoxy with mechanical stirring and sonication is widely used to disperse nanoclay in epoxy [1, 2, 3, 4, 5]. However it is not enough for well dispersion of clay in epoxy. Yasmin et al. [6] used a three-roll mill to disperse the clay nanoparticles in an epoxy matrix and improved distributions of nanoclay particles in epoxy. Chen and Tolle [7] achieved the fully exfoliated layer silicate epoxies by high-shear mixing in the presence of acetone. Liu et al. [8, 9, 10] used a high pressure mixing method with assistance of acetone solvent to improve the dispersion of clay in epoxy and obtained strong improvement on fracture toughness of epoxy nanocomposites. However, a lot of solvent were used as well as time was required for removing the solvent. There is still work to be done to develop nanocomposites with fine dispersions and exfoliated morphologies. Achieving such morphologies with epoxy-based nanocomposites is a challenge, since high shear is always required but epoxy has low viscosity. In this paper, exploration of a different way to generate the shear in order to improve the quality of dispersion and intercalation/exfoliation of clay in epoxy is discussed. 2 Experimental Epoxy and clay were mixed together by different devices. The first one was a room temperature without mechanical shear process (Rm), in which the clay and epoxy were stirred at room temperature by hand at 100 rpm for a few minutes then kept at room temperature for 1 hour. The second one was a high temperature without shear process (Tm), in which the clay and epoxy were stirred at 120°C by hand at 100 rpm for a few minutes then kept in an oven at 120°C for 1 hour. The third method was a high temperature with low speed process (TM), in which the clay and epoxy were stirred at 120°C for 1 hour by a mechanical stirrer at 1000 rpm. The fourth one was a room temperature and high speed process (RS), in which the clay and epoxy were stirred at room temperature by a homogenizer at high speed of 24000 rpm for 1 h. The fifth method was a high temperature and high speed process (TS), in which the clay and epoxy were stirred at 120°C by a homogenizer at high speed of 24000 rpm for 1 h. The sixth one was a high pressure process (HP), in which organoclay was first dispersed in acetone (about 8% of organoclay in acetone) to form a suspension with 1