Reworkable layered silicate-epoxy nanocomposites: synthesis, thermomechanical properties and combustion behaviour

Epoxy resin/montmorillonite nanocomposites were obtained via in situ intercalative polymerisation. The polymer matrix consists of anhydride-cured epoxy, and the choice of catalyst allows exchange reactions without depolymerisation. This makes the resin insoluble and reprocessable at the same time and potentially recyclable. In this study, reprocessing of the nanocomposites was done by mechanical grinding and re-welding by compression moulding at high temperature, similarly to thermoplastics. The effect of this process on the level of clay dispersion is discussed. Nanocomposite superstructures were imaged by means of transmission electron microscopy, and montmorillonite interlayer spacings were estimated by small angle X-ray scattering. The thermomechanical and combustion properties of the nanocomposites were investigated by means of dynamic mechanical thermal analysis, thermogravimetric analysis and cone calorimetry. The material tensile complex modulus E* was improved by nanocomposite formation, also after the glass transition occurred. Flammability of the material was moderately affected by the dispersed clay.