The electrical, rheological properties and phase change behavior of polypropylene (PP)/ polystyrene (PS) blends filled with multi-walled carbon nanotube (MWNT) were investigated. Two kinds of masterbatch were used to prepare ternary blends of PP, PS, and MWNT, and the effects of the kinds of masterbatch were confirmed by phase morphology of ternary blends and the distribution of MWNT. From thermodynamic analysis, MWNT is expected to locate in PS phase and it shows a good agreement with the TEM observations. The ternary composites show the lowest conductive percolation threshold and fine morphologies when most MWNT particles are located at the interface. Time sweep test were carried out to monitor the phase coalescence of the ternary blends and MWNT migration and agglomeration in the PS phase during annealing. The enhancement of thermal properties of MWNT-filled blends was also investigated by DSC and TGA.

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Abstracts: Poly(ethylene-co-vinyl acetate) (EVA)/clay nanocomposites were prepared using a melt mixer and then crosslinked with electron beam irradiation. To improve the dispersion of clay in the EVA matrix, high-intensity ultrasound was imposed during mixing. The tensile strength increased and the elongation at break decreased with the irradiation dose, respectively. The tensile strength increased remarkably when ultrasound was applied for better dispersion. Thermogravimetric analysis (TGA) showed that the thermal stability of EVA/clay nanocomposites increased with the irradiation dose and the dispersity of clay. The improvement in the thermal and mechanical properties could be attributed to the enhanced dispersion of clay and the network formed by radiationinduced crosslinking.

The cure kinetics of the epoxy-layered, silicate nanocomposites were studied by differential scanning calorimetry under isothermal and dynamic conditions. The materials used in this study were o-cresol novolac epoxy resin and phenol novolac hardener, with organically modified layered silicates. Various kinetic parameters, including the reaction order, activation energy, and kinetic rate constants, were investigated, and the storage stability of the epoxy-layered silicate nanocomposites was measured. To synthesize the epoxy-layered silicate nanocomposites, the phenolic hardener underwent pre-intercalation by layered silicate. From the cure kinetics analyses, the organically modified layered silicate decreased the activation energy during cure reaction in the epoxy/phenolic hardener system. In addition, the storage stability of the nanocomposite with the pre-intercalated phenolic hardener was significantly increased compared to that of the nanocomposite with direct mixing of epoxy, phenolic hardener, and layered silicate. This was due to the protective effect of the reaction between onium ions and epoxide groups.

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