Polystyrene-Epoxy Syntactic Foam

Another example of the use of expandable powder involves the use of polystyrene powder. The powder is mixed with a liquid-matrix-resin system, such as epoxy. The exotherm of the curing epoxy resin expands the expandable polystyrene powder to form a syntactic foam. 

Polystyrene-Epoxy Syntactic Foam. Hollow polystyrene microspheres are produced by heating expandable polystyrene (in other words gas-filled spheres, e.g., propane or butane-filled polystyrene) of microscopic size. The expandable polystyrene microspheres may be added to the epoxy-resin formulation, and the exothermic heat (or the heat during oven cure) can be employed for the expansion. In this manner, foams having densities as low as 80 kg/m (5 Ib/ft ) may be developed. 

---