Cementitious material reinforced by carbon nanotube-Nylon 66 hybrid nanofibers: Mechanical strength and microstructure analysis

In this study, carbon nanotube (CNT) reinforced Nylon 66 nanofibers were used to modify the mechanical properties of cementitious materials. Single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) were dispersed into the polymer solution of Nylon 66. CNT reinforced Nylon 66 nanofibers were fabricated and mixed directly with ordinary Portland cement through an electrospinning process using an improved collector. Scanning electron microscope (SEM) and field emission transmission electron microscope (FE-TEM) were employed to investigate the morphological characteristics of nanofibers as well as the performance of nanofibers in the microstructure of hardened cement pastes. Moreover, the existence of CNTs in the hardened cement pastes was clarified by means of micro-computed tomography (CT) technique and thermal gravimetric analysis (TGA) method. The observations from mechanical strength tests showed the increase in toughness by 49 %, 30 % and 12 % as well as the increase in the tensile strength by 28 %, 43 % and 57 % in that order when adding Nylon 66 nanofibers, SWCNT reinforced Nylon 66 nanofibers and MWCNT reinforced Nylon 66 nanofibers into cement pastes.