The effect of functionalization on the viscoelastic behavior of multi-wall carbon nanotube/epoxy composites

Functionalized multi-walled carbon nanotubes with hydroxyl groups (MWNT-OH) and non-functionalized MWNT were used to fabricate MWNT/epoxy composite samples by sonication technique. The viscoelastic properties of the composite samples were evaluated by performing dynamic mechanical thermal analysis (DMTA) test. The results showed that addition of nanotubes to epoxy had significant effect on the viscoelastic properties. Samples containing functionalized nanotubes showed a stronger influence on Tg in comparison to composite samples containing similar amount of non-functionalized nanotubes. The viscoelastic behavior was modeled by plotting the COLE–COLE diagram using the results of DMTA test. There was a good agreement between the Perez model and the viscoelastic behavior of the composite specimen.

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► The hydroxyl groups on the MWNT surface increased the dispersion in the epoxy matrix.
► The rubbery modulus for 0.5 wt.% MWNT and MWNT-OH was 9.1% and 71.8% higher than that of neat epoxy.
► The α-relaxation temperature increased with the addition of MWNT-OH.
► The addition of nanotubes did not have any effect on the β relaxation temperature.