Amine-terminated chain-grafted nanodiamond/epoxy nanocomposites as interfacial materials: Thermal conductivity and fracture resistance

Nanodiamond (ND) surfaces were successfully modified using the ozone treatment and tetraethylenepentamine (TEPA) solution for use as reinforcement in epoxy nanocomposites. The main purpose of the project was to introduce ozone/TEPA-functionalized NDs within the epoxy matrix to improve its thermal conductivity and fracture resistance by enhancing interfacial interactions. To confirm the efficacy of the proposed method, ND/epoxy nanocomposites were fabricated with three types of ND (pristine ND, ozone-functionalized ND, and ozone/TEPA-functionalized ND) at different amounts; the ND contents were found to be optimal at 0.50 wt% for all of the nanocomposites developed in this work. With the addition of this amount of the ozone/TEPA-functionalized NDs, the thermal conductivity and fracture toughness of the nanocomposite were enhanced by 34.1 and 121.4%, respectively, compared with pristine ND. The related ND reinforcing mechanisms were also analyzed, and the enhancements of dispersion and interfacial properties can mainly be attributed to thermal and mechanical interlocking effects. The obvious advantage of this approach is that the ozone/TEPA-functionalized NDs can prevent the aggregation process of nanostructures, thereby demonstrating interface synergism within nanocomposites with the final outcomes of better thermal conductivity and fracture resistance within the epoxy matrices under an equivalent load.