Advantages and disadvantages of the addition of graphene nanoplatelets to epoxy resins

• Effect of the graphene nanoparticles on the behavior of epoxy resins.
• Modulus in glassy state is widely increased by the GNP addition.
• Electrical and thermal conductivities increase significantly and simultaneously.
• Graphene increases the hydrothermal resistance of resins.

Graphene nanoplatelets (GNPs), in different contents, are added to epoxy resin. This work mainly consists of a deep characterization of the composites in order to evaluate their behavior regarding neat epoxy resin. In fact, their main properties, such as their morphological features, their thermo-mechanical and mechanical properties, their electrical conductivity and thermal diffusivity, their hydrophobic behavior and their barrier properties have been studied. It is confirmed that the GNP addition induces an important stiffing of thermosetting resin. However, the rest of mechanical properties, strength and elongation, are diminished due to a weak interface formed between the epoxy matrix and non-functionalized GNPs. The electrical conductivity and thermal diffusivity show an important increase. Electrical conductivity increases several orders of magnitude from a minimum value of percolation while the thermal diffusivity increases proportionally to GNP content. Other advantage of the GNP addition is the increase of the hydrophobic behavior of the composites, determined by measurements of contact angle of water drops. Finally, GNP/epoxy composites present higher barrier properties in humid environments. The addition of GNP decreases the maximum water content absorbed and the diffusion coefficient. However, this enhancement is not too large due to the weak interface and therefore the presence of hollows in the GNP/epoxy composites.

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