Improved mechanical properties through engineering the interface by poly (ether ether ketone) grafted graphene oxide in epoxy based nanocomposites

•Hydroxylated poly (ether ether ketone) [HPEEK] was covalently grafted on to graphene oxide (GO).•Grafting of HPEEK on GO through ester linkage which attributed to better interfacial interaction with epoxy.•Addition of HPEEK-g-GO in epoxy improves thermal stability as well as mechanical properties.

In this work, hydroxylated HPEEK [poly (ether ether ketone)] was covalently grafted on to graphene oxide (GO) sheets and methodically characterized using FTIR, TEM and XPS. The epoxy composites with GO and HPEEK grafted graphene oxide (HPEEK-g-GO) were prepared using mechanical stirring coupled with a bath sonicator to improve the dispersion and were subsequently cured at 80  °C and 180 °C. With the addition of only a small amount (0.5 wt%) of HPEEK-g-GO, an impressive 42% increase in storage modulus, 65% enhancement in hardness and 31% increase in fracture toughness was observed with respect to the control epoxy sample. In addition, significant enhancement in tensile strength by 7% was realized in epoxy composites containing 0.5 wt % of HPEEK-g-GO. This improvement in structural properties was attributed to reinforcement by HPEEK-g-GO having sound interface with epoxy. The epoxy composites containing HPEEK-g-GO also showed improvement in glass transition temperature along with the thermal stability up to 300 °C.

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