Hydroxyl Group Functionalization of Carbon Nanotubes and Its Effect on the Properties of Cement Stone

Abstract With the increasing progress of unconventional oil and gas wells, the performance of existing cementing water mud systems can hardly satisfy the harsh subsurface environmental conditions, and there is a necessity to develop high-performance nanomaterials to elevate the mechanical attributes of cement stones. In this paper, hydroxyl-functionalized carbon nanotubes (CNT-OH) dispersions were prepared by hydrophilic group functionalization modification with a strong oxidant, which effectively solved the problem of poor dispersion of carbon nanotubes (CNT) in aqueous environments and the difficulty of playing an enhancing and toughening role in cements stones. It was shown that the hydrophilicity of CNT-OH was significantly improved, and the contact angle was decreased from 139.01° to 52.03°, while the physical phase and morphology of the raw material of carbon nanotubes remained unchanged. The average particle size of the dispersion was reduced by 87.91% from hydrophobic to hydrophilic materials, and the dispersing ability in water was significantly improved. Meanwhile, the dispersion stability of CNT-OH in water was improved by 97%. In addition, the incorporation of 0.005% CNT-OH can enhance the compressive strength and flexural strength of cement by 17.54% and 48.76%, respectively.