Supercritical CO2 as an exfoliating aid for nanocomposite preparation: Comparison of different processing methodologies

This article examines several new methods for compounding nanocomposite materials by twin screw extrusion that use supercritical CO2 as a processing aid to produce more highly exfoliated polyolefin‐layered silicate nanocomposites than conventional melt intercalation. These methods varied the manner in which the plasticizing behavior of CO2 influences the surfactant of an organoclay, the compatibilizer, and the matrix during preparation of a polyolefin nanocomposite. The results have shown that targeting CO2 to the organoclay‐compatibilizer interface can improve the extent of intercalation. However, reduced performance was observed when CO2 was introduced predominantly to the matrix or neat organoclay. In general, the different techniques of addition for CO2 did bring about greater structural changes to the organoclay, but the stiffness of the resulting materials was lower than simply following a conventional melt intercalation approach. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers