A Novel Method Of Nanoclay Exfoliation In Thermoset Composite Materials

The use of exfoliated layered silicates as reinforcing filler in polymer composites shows great potential for improving material properties. Thermoset systems have been increasingly studied; however literature has shown that attaining necessary levels of clay exfoliation in these materials is a challenge using current dispersion technology. In this study, various methods were explored to optimize the degree of clay exfoliation in thermoset polyimide resins. Various organic treatments of the layered silicate clay were examined, including aliphatic, aromatic, and reactive surfactants. In addition, this study explored a novel method of clay exfoliation, in which the clay was first intercalated with lower molecular weight oligomers and then dispersed into a higher molecular weight matrix resin. During curing, the elastic force within clay galleries grew at a higher rate than viscosity of the surrounding resin, and the clay platelets were pushed apart to yield an exfoliated clay structure. The thermal and mechanical properties of carbon fiber laminate composites and the clay spacing were evaluated. The resultant composites showed increased barrier properties, improved thermal stability, and increased flexural strength and strain compared to composites of neat resin. The results of this work may be applicable to development of clay nanocomposites in the rubber industry.