Development of photo micro-graph method to characterize dispersion of CNT in epoxy

In this study, mechanical test have been performed on neat epoxy, 0.1%, 0.2%, 0.3% and 0.4% CNTs reinforced epoxy. Testing results indicated that the highest improvement in strength and fracture toughness was obtained with 0.3 wt% CNT loading. SEM pictures of fracture surface showed that, during the failure process, cleavage steps are formed when the crack propagation changed direction as it crossed CNTs. The flat cleavage planes were formed by the network of cleavage steps and roughness of fracture surface increased after infusing of CNT. Based on this mechanism, a photo micrographic method was established to determine dispersion of CNT in epoxy by measuring the distance between two cleavage steps. Statistical analysis results indicated that the average distance of two cleavage steps decreased with increasing CNT content. Two dispersion peaks in 0.3% system indicate initialization of agglomeration.