Compression Behavior of Single-layer Graphene

TL;DR

This study investigates the compression buckling behavior of single-layer graphene embedded in plastic beams, revealing high buckling strains and significant enhancement due to lateral support, with detailed stress and buckling measurements.

Contribution

It provides detailed experimental data on the compression buckling of monolayer graphene, extending previous work by measuring stress uptake and buckling strains in various geometries using Raman spectroscopy.

Findings

Graphene exhibits buckling strains of -0.5% to -0.6% for large aspect ratios.

No failure observed even at strains higher than -1% for small aspect ratios.

Lateral support from polymer increases buckling strain by over six orders of magnitude.

Abstract

Central to most applications involving monolayer graphene is its mechanical response under various stress states. To date most of the work reported is of theoretical nature and refers to tension and compression loading of model graphene. Most of the experimental work is indeed limited to bending of single flakes in air and the stretching of flakes up to typically ~1% using plastic substrates. Recently we have shown that by employing a cantilever beam we can subject single graphene into various degrees of axial compression. Here we extend this work much further by measuring in detail both stress uptake and compression buckling strain in single flakes of different geometries. In all cases the mechanical response is monitored by simultaneous Raman measurements through the shift of either the G or 2D phonons of graphene. In spite of the infinitely small thickness of the monolayers, the results show that graphene embedded in plastic beams exhibit remarkable compression buckling strains. For large length (l)-to-width (w) ratios (> 0.2) the buckling strain is of the order of -0.5% to -0.6%. However, for l/w <0.2 no failure is observed for strains even higher than -1%. Calculations based on classical Euler analysis show that the buckling strain enhancement provided by the polymer lateral support is more than six orders of magnitude compared to suspended graphene in air.