(255d) Suspension Polymerization of Inverse Emulsion of Water Expandable Polystyrene/Clay Nanocomposites

In order to improve the compatibility between the inorganic clay and the organic polymer, conventional methods to prepare polymer/clay nanocomposite foams require the use of surfactants, quaternary ammonium compounds, as a surface modifier to render the clay surface hydrophobic. The quaternary ammonium, however, is an extreme fire hazard. In this work, a new technique was developed to synthesize the water expandable polystyrene (PS)/clay nanocomposites without surface modification of nanoclay, while still keeping the good dispersion of clay. The expandable composite beads were further heated above the Tg of the polymer matrix to form the cellular structures.

Compared to the conventional water expandable PS, the incorporation of nanoclay changes the morphology of polymer foam. Moreover, the barrier properties of clay can mitigate the diffusion of water thought PS during the period of expansion, leading to an improved foaming performance. From the standpoint of the polymeric foam industry, this technique bridges the advantages of both the fire resistance and the property enhancement.