Mechanical properties of micro-patterned carbon nanotube foams

L. Lattanzi, L. De Nardo, C. Daraio
California Institute of Technology, US

Keywords: micro-patterned CNT structures, microstructural geometry, density, energy absorption

Summary:

Micro-patterned CNT-foams were designed and fabricated using photolithography technique. CNT structures were grown on silicon wafers in three different geometries: lines, pillars and concentric rings with variable dimensions. For the synthesis, we used a chemical vapor deposition method, and tested all samples using an Instron 3000 test system. We measure energy absorption, maximum stress and strain recovery under bulk, quasi-static uniaxial compression. Results showed that lower density micro-patterned CNT foams (e.g., concentric rings patterns) are able to retain the same energy absorption properties than those observed in the non-patterned CNT foams. To evaluate the effects of the pattern geometry, we compared the stress-strain curves obtained testing patterned structures with the same density (e.g., concentric rings and lines with gap 100 μm, both with density ~ 0.02 g cm-3). The concentric rings pattern exhibited higher energy absorption capability, higher maximum stress and better strain recovery. By designing and fabricating micro-patterned multiscale CNT structures, it is possible to create materials with controllable microstructural geometries and density. We were able to create lighter structures preserving the mechanical response of bulk CNT foams, and we characterized the effects of the patterns’ geometry.