In-situ pressing synthesis of densely compacted carbon nanotubes reinforced nanocomposites with outstanding mechanical performance

Hot/cold pressing is a very common process in powder metallurgy and polymer industry, in which powders are compacted at a temperature/pressure high enough to induce sintering and creeping processes, and make the materials much denser and stronger. In this study, we extent this strategy to the synthesis of carbon nanotube (CNT) nanocomposites, yet with the high compressive stress generated naturally during the ultra-filtration process. Employing dead filtration, which is traditionally employed to extract solids from solution in water treatment process, we fabricate CNTs/PVA nanocomposites with high CNTs loading. It was found that this process not only greatly accelerates the filtration, but also generates significant in-situ pressure on the nanocomposites during its formation. Such pressure can compress the nanocomposites in-situ from the very onset of the formation of the nanocomposites and at molecular scale, which makes the nanocomposites densely compacted and eventually translates to very high mechanical properties even at high CNTs concentrations of up to ∼90 vol%. The tensile strength and Young's modulus can be increased by 435% and 859%, respectively, and the toughness is comparable with the nacre at similar content of inorganic constituent.