Improving the exfoliation of layered silicate in a poly(ethylene terephthala te) matrix using supercritical carbon dioxide

Abstract

A technique for improving the exfoliation of organically modified layered silicate (OMLS) in a poly(ethylene terephthalate) (PET) matrix using super critical carbon dioxide (scCO2) is compared to traditional direct melt blending. The process relies on the rapid expansion of a scCO 2/OMLS mixture directly into the second stage of a single screw extruder where the clay and scCO2 mixture is subsequently melt blended with the PET matrix. The simple, environmentally benign process results in a more highly delaminated system than traditional direct melt compounding. X-ray diffraction analysis is used to reveal improved clay morphologies and the resulting mechanical properties are examined. Rheology is used as a tool to draw conclusions about the effect that scCO2 has on reducing PET matrix degradation during processing. © 2009 Society of Plastics Engineers.