Polystyrene/clay nanocomposites mechanical properties

The addition of nanoparticles to synthetic rubber resulting in enhancement in thermal, stiffness and resistance to fracture is one of the most important phenomena in material science technology. The commonly used white filler in mbber industry are clay and silica. The polymer/clay nanocomposites offer enhanced thermo mechanical properties. Bourbigot et al. observed that the thermal stability of polystyrene (PS) is significandy increased in presence of nanoclay [75]. Thermal and mechanical properties of clays multiwalled carbon nanotubes reinforced ethylene vinyl acetate (EVA) prepared through melt blending showed synergistic effect in properties [76]. 

T. Yamaguchi and E. Yamada, Preparation and mechanical properties of clay/polystyrene-block-polybutadiene-block-polystyrene triblock copolymer (SBS) intercalated nanocomposites using organoclay containing stearic acid. Polymer International, 55 (2006), 662-7. 

Two polymerizable cationic surfactants were synthesized to produce thermally stable organoclays (ll-acryloyloxyundecyl)dimethyl(2-hydroxyethyl)ammonium bromide (called hydroxyethyl surfmer), and (ll-acryloyloxyundecyl)dimethylethylammonium bromide (called ethyl surfmer (Table 3.5) [63]. PS nanocomposites were produced by bulk polymerization and by free radical polymerization using these organoclays. Exfoliated structures were obtained with the ethyl surfmer-modified clay, whereas a mixed exfoliated/ intercalated structure was obtained using the hydroxyethyl surfmer-modified clay. The nanocomposites exhibited enhanced thermal stability and an increase in the glass transition temperature, in addition to improved mechanical properties relative to polystyrene. However, intercalated structures were obtained when nanocomposites were prepared in solution, because of competition between the solvent molecules and monomer in penetrating the clay galleries. Enhanced thermal stability was also obtained in the solution polymerization case. 

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