Influence of carbon nanoparticle modification on the mechanical and electrical properties of epoxy in small volumes

Abstract

The influence of nanoparticle morphology and filler content on the mechanical and electrical properties of carbon nanoparticle modified epoxy is investigated regarding small volumes. Three types of particles, representing spherical, tubular and layered morphologies are used. A clear size effect of increasing true failure strength with decreasing volume is found for neat and carbon black modified epoxy. Carbon nanotube (CNT) modified epoxy exhibits high potential for strength increase, but dispersion and purity are critical. In few layer graphene modified epoxy, particles are larger than statistically distributed defects and initiate cracks, counteracting any size effect. Different toughness increasing mechanisms on the nano- and micro-scale depending on particle morphology are discussed based on scanning electron microscopy images. Electrical percolation thresholds in the small volume fibres are significantly higher compared to bulk volume, with CNT being found to be the most suitable morphology to form electrical conductive paths. Good correlation between electrical resistance change and stress strain behaviour under tensile loads is observed. The results show the possibility to detect internal damage in small volumes by measuring electrical resistance and therefore indicate to the high potential for using CNT modified polymers in fibre reinforced plastics as a multifunctional, self-monitoring material with improved mechanical properties.

Enhancement of Fracture Toughness of Epoxy Nanocomposites by Combining Nanotubes and Nanosheets as Fillers

“…Bowing lines are seen, suggesting that crack-pinning is still occurring, leading to the increase in fracture toughness. The coarse nature of the fracture surfaces observed in Figure 8 a,b for both hybrid systems indicates that the inclusion of the 1D and 2D nanofillers have led to the deflection of crack path [ 31 ]. This development initiates off-plane loading that originate new fracture surfaces, hence leading to an increase in the mode I fracture toughness.…”

Extreme scale-dependent tensile properties of epoxy fibers

“…Hobbiebrunken et al [13] proposed a method to produce μm-sized epoxy fibers, the average strength of which was found to be remarkably close (60%) to the theoretical strength. Leopold and coworkers [14,15] used a similar experimental routine to investigate the size effect of carbonaceous fillers (graphene, carbon nanotubes and carbon black). In both studies the origin of the size effect on strength was attributed to the statistical distribution of defects.…”

Review on Recent Advancements in the Field of Reinforced Epoxy Nano Composits

“…Leopold et al, [8] calculated the Influence of carbon nanoparticle modification on the mechanical and electrical properties of epoxy in small volumes. Three types of particles, representing spherical, tubular and layered morphologies are used.…”