Fracture of the Intermolecular Hydrogen Bond Network Structure of Glycerol Modified by Carbon Nanotubes

An intermolecular hydrogen bond network structure is usually formed in the liquid state and affects physicochemical properties, such as melting point, boiling point, and viscosity. The intermolecular hydrogen bond network structure plays an important role in the viscosity of lubricating oil; that is, the broken bond decreases the viscosity. To determine the effect of intermolecular hydrogen bond network structure on viscosity, this study used glycerol, which contains a large amount of intermolecular hydrogen bonds, as a research object. Single- and double-walled carbon nanotubes (SWNTs and DWNTs, respectively) were used as modifiers. The glycerol mixture and the carbon nanotubes were characterized by rheology, Raman spectroscopy, transmission electron microscopy (TEM), H-1 NMR, and computer modeling. Results showed that the carbon nanotube modified the intermolecular hydrogen bond network, leading to reduced glycerol viscosity. The two types of nanotubes exhibited varied effects on glycerol viscosity. The SWNTs and DWNTs decreased the viscosity by up to 2.97 and 1.81%, respectively. The Raman, H-1 NMR, and TEM results indicated that the intermolecular hydrogen bond network structure was destructed because of the capillary action of the carbon nanotube. Computer simulation also showed that the carbon nanotube had space-limiting function, which could separate the new glycerol molecule clusters from one another to terminate hydrogen bonding in the body phase.