Effect of clay surface modification on the polymer nanocomposite foam structure

Nanoclay can work as a nucleation agent to control foam cell structure and reinforcement to enhance foam properties. In this paper, the clay surface is modified by a reactive quaternary ammonium surfactants and grafted with either poly(methyl methacrylate) (PMMA) or polystyrene (PS). The polystyrene and the polymer modified clay nanocomposites are synthesized by in-situ polymerization and extrusion compounding. By using CO₂ as the foaming agent, the nanocomposite foams are prepared in a single screw extruder. It is found that the surface modification has a great influence on the foam morphology. The presence of more CO₂-philic PMMA on the clay surface leads to a lower melt viscosity.