Effect of sonication parameters on the mechanical properties of multi-walled carbon nanotube/epoxy composites

• Increasing sonication time leads to better dispersion of MWNTs.
• Over sonication results in degradation of mechanical properties of nanocomposites.
• Applying moderate sonication time and power leads to the highest Tg.
• Introduction of higher sonication power compensate less time.
• Depending on the desirable mechanical properties, optimum power and time vary.

In this study, the effects of duration and output power of sonication on the dispersion state of 0.5 wt.% multi-walled carbon nanotube (MWNT) in epoxy matrix were investigated. To disperse the MWNT in the polymer matrix, sonication powers of 25, 50 and 100 W and sonication times of 15, 45 and 135 min were used. Dynamic mechanical thermal analysis (DMTA) and tensile test were performed under different dispersion states of MWNT. The results indicated that with increase in the sonication time, there was an initial increase in Young’s modulus values followed by a drop in values at longer sonication times. The highest Young modulus was gained for the sonication power of 50 W and sonication times of 45 min. Also the highest tensile strength was obtained for the sonication power of 25 W and sonication time of 45 min. Also sonication at 50 W for 15 min was the most effective dispersion for achieving the highest glass transition temperature (Tg). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the dispersion state of MWNT. Well dispersion was observed as the power and duration of sonication were increased.

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