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Carbon nanotube (CNT)/epoxy nanocomposites have a great potential of possessing many advanced properties. However, the homogenization of CNT dispersion is still a great challenge in the research field of nanocomposites. This study applied a novel dispersion agent, carboxymethyl cellulose (CMC), to functionalize CNTs and improve CNT dispersion in epoxy. The effectiveness of the CMC functionalization was compared with mechanical mixing and a commonly used surfactant, sodium dodecylbenzene sulfonate (NaDDBS), regarding dispersion, mechanical and corrosion properties of CNT/epoxy nanocomposites with three different CNT concentrations (0.1%, 0.3% and 0.5%). The experimental results of Raman spectroscopy, particle size analysis and transmission electron microscopy showed that CMC functionalized CNTs reduced CNT cluster sizes more efficiently than NaDDBS functionalized and mechanically mixed CNTs, indicating a better CNT dispersion. The peak particle size of CMC functionalized CNTs reduced as much as 54% (0.1% CNT concentration) and 16% (0.3% CNT concentration), compared to mechanical mixed and NaDDBS functionalized CNTs. Because of the better dispersion, it was found by compressive tests that CNT/epoxy nanocomposites with CMC functionalization resulted in 189% and 66% higher compressive strength, 224% and 50% higher modulus of elasticity than those with mechanical mixing and NaDDBS functionalization respectively (0.1% CNT cencentration). In addition, electrochemical corrosion tests also showed that CNT/epoxy nanocomposites with CMC functionalization achieved lowest corrosion rate (0.214 mpy), the highest corrosion resistance (201.031 Ω·cm2), and the lowest porosity density (0.011%). 

The remarkable mechanical properties and piezo-responses of carbon nanotubes (CNT) makes this group of nanomaterials an ideal candidate for use in smart cementitious materials to monitor forces and the corresponding structural health conditions of civil structures. However, the inconsistency in measurements is the major challenge of CNT-enabled smart cementitious materials to be widely applied for force detection. In this study, the modified tapioca starch co-polymer is introduced to surface treat the CNTs for a better dispersion of CNTs; thus, to reduce the inconsistency of force measurements of the CNTs modified smart cementitious materials. Cement mortar with bare (unmodified) CNTs (direct mixing method) and surfactant surface treated CNTs using sodium dodecyl benzenesulfonate (NaDDBS) were used as the control. The experimental results showed that when compared with samples made from bare CNTs, the samples made by modified tapioca starch co-polymer coated CNTs (CCNTs) showed higher dynamic load induced piezo-responses with significantly improved consistency and less hysteresis in the cementitious materials. When compared with the samples prepared with the surfactant method, the samples made by the developed CCNTs showed slightly increased force detection sensitivity with significantly improved consistency in piezo-response and only minor hysteresis, indicating enhanced dispersion effectiveness. The new CNT surface coating method can be scaled up easily to cater the potential industry needs for future wide application of smart cementitious materials.