Preparation and characterization of graphite nano-platelet (GNP)/epoxy nano-composite: Mechanical, electrical and thermal properties

• Mechanical, thermal and electrical properties of graphite nano-platelet/epoxy composite.
• Electrical percolation threshold was achieved at 0.3 wt%, which is higher than the percolation threshold of carbon nanotube/epoxy composite.
• Improvement in the fracture toughness of pure epoxy by 36% due to the geometry of the filler.
• Crack deflection and micro-cracking are the major toughening mechanisms in GNP/epoxy composite.

Epoxy based polymer nano-composite was prepared by dispersing graphite nano-platelets (GNPs) using two different techniques: three-roll mill (3RM) and sonication combined with high speed shear mixing (Soni_hsm). The influence of addition of GNPs on the electrical and thermal conductivity, fracture toughness and storage modulus of the nano-composite was investigated. The GNP/epoxy prepared by 3RM technique showed a maximum electrical conductivity of 1.8 × 10−03 S/m for 1.0 wt% which is 3 orders of magnitude higher than those prepared by Soni_hsm. The percentage of increase in thermal conductivity was only 11% for 1.0 wt% and 14% for 2.0 wt% filler loading. Dynamic mechanical analysis results showed 16% increase in storage modulus for 0.5 wt%, although the Tg did not show any significant increase. Single edge notch bending (SENB) fracture toughens (KIC) measurements were carried out for different weight percentage of the filler content. The toughening effect of GNP was most significant at 1.0 wt% loading, where a 43% increase in KIC was observed. Among the two different dispersion techniques, 3RM process gives the optimum dispersion where both electrical and mechanical properties are better.

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