Intercalation And Exfoliation Behavior Of Clay In Thermoset Resin/Clay System

The intercalation and exfoliation behavior of lamellar clay in the thermoset resin/clay composites during curing was studied in this paper.For epoxy/organoclay system, intercalation and exfoliation behavior of organoclays in epoxy resin has been investigated. It was found that the organoclays were easy to be intercalated by epoxy and formed a stable epoxy/clay intercalated hybrid. In epoxy/clay composites, epoxy was cured in different environments: intra-gallery and extra-gallery. By variation of curing agents of epoxy and modifier of clay, the different curing speed of intra-gallery and extra-gallery could be obtained. It was found that exfoliation of clay occurred when the curing speed of intra-gallery was faster than that of extra-gallery even the epoxy/clay compositions were cured at any temperatures, for any time and with any types of curing agents. While the curing speed of intra-gallery was slower than that of extra-gallery, exfoliation never happened.The mechanical properties of different epoxy/clay composites were measured. The results indicated that the exfoliation of clay sheets in epoxy resin was essential for better properties of the nanocomposites. For exfoliated epoxy/clay nanocomposites, its mechanical properties were optimal when the content of the clay was about 2wt%. Compared with pure epoxy resin, the impact strength, the stress strength and thermal stability of nanocomposites were improved in certain degree.For phenolic resin/clay system, the intercalation and exfoliation of organoclay in phenolic and novolac resin were also investigated. It was found that only intercalating nanocomposites be prepared by melt polymerization, and the organoclays deintercalated when curing took place. Exfoliated novolac resin/clay nanocomposites can be prepared when such composites were cured in the presence of ethanol, which was employed as solvent. The influence of solvent on the microstructure of novolac resin/clay compositesiiiwas studied. It is suggested that the introduction of ethanol as solvent not only decrease the viscosity of composites allowing the easy mass transfer of resin and curing agent during curing, but also weakens the intermolecular interaction of novolac resin resulting better miscibility of resin and clay. By same method, exfoliated phenolic resin/novolac resin/clay nanocomposites can be synthesized. The thermal stability of novolac resin/clay nanocomposites was improved when compared with pure novolac resin.