Synthesis and characterisation of thermoset-clay nanocomposites

Sammanfattning: Polymer-clay nanocomposites are materials reinforced on a molecular scale by 1 nm-thick clay layers dispersed in a polymer matrix. Thermoset-clay nanocomposites were synthesised from unsaturated polyester and epoxy resins with two different approaches. The unsaturated polyester-clay nanocomposite was synthesised by treating the clay with silanes and mixing it with the resin prior to curing. The clay was partially delaminated and substantial improvements of mechanical properties were observed. The epoxy-clay nanocomposite was synthesised by swelling alkylammonium treated clay in a diglycidyl ether of bisphenol A resin with subsequent polymerisation. Both the nature of the clay and the curing agent had significant effect on the resulting structure of the nanocomposite, which is mainly governed by cure kinetics and diffusion mechanisms. The curing temperature permits to adjust a balance between these two mechanisms. The analysis of the structure of delaminated epoxy-clay nanocomposites reveals the presence of multiplets of non-delaminated layers. Large stiffness improvements were observed for intercalated and delaminated epoxy-clay nanocomposites as well as an important decrease of molecular mobility as compared with a conventional composite.