Preparation, characterization and properties of montmorillonite/epoxy compounds

In order to utilize the expanding nature of smectite clays in the compensation of shrinkage in epoxy systems, several "epoxyphilic" montmorillonites were prepared via ion exchange reactions. These epoxyphilic montmorillonites contain moieties within their structures that can react with either the epoxide resin, curing agent or both.;The swelling behavior of aminolauric acid-intercalated montmorillonite (ALA-MMT) was studied under various swelling conditions prior to curing of the epoxy. It was determined that to obtain larger montmorillonite interlayer distances in the cured epoxy, the ALA-MMT should be swollen in the curing agent rather than the epoxide resin. The curing reaction was shown to increase the interlayer spacing of the ALA-MMT more efficiently when swollen in the curing agent rather than the epoxide resin. Based on these results, models for the swelling behavior of ALA-MMT is proposed.;The addition of 2-5% epoxyphilic montmorillonite to epoxy was observed to reduce the maximum residual stress by more than 50%. The glass transition temperatures of these clay/epoxy compounds were generally higher than the pure epoxy. The modulus and ultimate strengths of these compounds were as high or higher than pure epoxy. However, due primarily to large agglomerations of montmorillonite particles, the ultimate elongation was drastically reduced.