(751b) Thermal, Mechanical Properties, and Fracture Toughness of Surface Modified Graphene Epoxy Nanocomposites

Addition of nanoparticles to the host polymer matrix has resulted in improvements of stiffness and moduli, increased glass transition temperature, enhanced thermal stability, improved electrical and thermal conductivity, enhanced barrier properties, and thermal barrier coating. Graphene is SP² hybridized 6-membered carbon ring monoatomic thick with micron-sized lateral dimension exhibited superior electrical, thermal, and mechanical properties when incorporated in polymer matrices, such as polyvinyl alcohol, polystyrene, and polycarbonate.

Series of low concentration graphene bisphenol-A epoxy nanocomposites, (0.01-1 wt%), with reduced graphene, oxygenated graphene, and aminopropyl terminated polydimethylsiloxane modified graphene were prepared using solvent mixing method. The attachment of aminopropyl terminated polydimethylsiloxane to the graphene was verified with IR and TGA.

Thermal stability of all nanocomposites was higher with increased onset of thermal degradation compared to the neat epoxy. Glass transition temperature of all graphene nanocomposites exhibited 5-10 ^oC increase compared to the neat epoxy resin. The storage tensile modulus of the all nanocomposite were higher than the neat epoxy where the moduli of the graphene with oxygenated functional groups increased with increasing graphene concentration. The moduli of the reduced graphene epoxy nanocomposites had an initial increase and then remained constant, where the moduli of the PDMS-graphene epoxy nanocomposites exhibited an initial increase followed by a decrease with increasing graphene concentration. Fracture toughness of graphene epoxy nanocomposites were 30-40% higher than the neat epoxy resin with only addition of 0.01-0.05 wt% graphene. Fractured surface of the nanocomposites were examined by scanning electron microscopy.