Influence of macro-topography on damage tolerance and fracture toughness of 0.1 wt % multi-layer graphene/clay-epoxy nanocomposites

Influence of topographical features on mechanical properties of 0.1 wt % Multi-Layer Graphene (MLG)/clay-epoxy nanocomposites has been studied. Three different compositions were made: (1) 0.1 wt % MLG-EP; (2) 0.1 wt % clay-EP and (3) 0.05 wt % MLG-0.05 wt % clay-EP. The objective of making hybrid nanocomposites was to determine whether synergistic effects are prominent at low weight fraction of 0.1 wt % causing an improvement in mechanical properties. The topographical features studied include waviness (Wa), roughness average (Ra), root mean square value (Rq) and maximum roughness height (Rmax or Rz). The Rz of as-cast 0.1 wt % MLG-EP, clay-EP and 0.05 wt % MLG-0.05 wt % clay-EP nanocomposites were 43.52, 48.43 and 41.8 µm respectively. A decrease in Rz values was observed by treating the samples with velvet cloth and abrasive paper 1200P while increased by treating with abrasive papers 320P and 60P. A weight loss of up to 16% was observed in samples after the treatment with the abrasive papers. It was observed that MLG is more effective in improving the mechanical properties of epoxy than nanoclay. In addition, no significant improvement in mechanical properties was observed in hybrid nanocomposites indicating that 0.1 wt % is not sufficient to generate conspicuous synergistic effects.