Fig. 5.

Lap-shear tests of GO films. a Schematic drawing showing the experimental configuration of the lap-shear test. A rectangular GO film (3 × 4 mm, around 10 µm thick) was glued between two parallel glass substrates using an epoxy adhesive. A shear stress was then applied by pulling the substrates in the opposite direction at a speed of 0.3 mm min⁻¹ up to film delamination. Shear stress–strain curves of films made of b pristine, un-etched GO, c 5-h-etched porous GO, and d pristine GO mixed with 25 wt% of 5-h-etched GO. For each type of GO film, 4–5 samples were tested. For all the samples shown here, delamination occurred from within the GO film, rather than at the adhesive-GO or adhesive-glass interfaces. e Summary of shear strength values for all measurements in b–d. Error bars represent SD