Exfoliation aids for preparation of polymer-layered silicate nanocomposites

The use of supercritical CO2 and two cosolvents, water and ethanol, were examined for their capability to aid the exfoliation of an organoclay within a thermoplastic polyolefin matrix. The study examined the manner in which the gas environment was used in the presence of the clay, compatibilizer and matrix. This was done through the use of a custom-built extensional flow mixer. The results of the work showed that supercritical CO2 was most effectively utilized when in the presence of the organoclay and compatibilizer as it melted. Use of the gas when only the organoclay was present resulted in poor stiffness properties for the final material. Both water and ethanol were effective cosolvents, producing smaller tactoids with a narrower size distribution. Ethanol was found to be the most effective as a cosolvent for supercritical CO2 with organoclays.