Supercritical 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 [CO.sub.2] 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 [CO.sub.2] influences the surfactant of an organoclay, the compatibilizer, and the matrix during preparation of a polyolefin nanocomposite. The results have shown that targeting [CO.sub.2] to the organoclay-compatibilizer interface can improve the extent of intercalation. However, reduced performance was observed when [CO.sub.2] was introduced predominantly to the matrix or neat organoclay. In general, the different techniques of addition for [CO.sub.2] 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., 52:2049-2062, 2012. © 2012 Society of Plastics Engineers