Aggregation of Synthetic Chrysotile Nanotubes In the Bulk and In Solution Probed By Nitrogen Adsorption and Viscosity Measurements

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Polymers and High Performance Materials


Chrysotile nanotubes (ChNTs) were synthesized under hydrothermal conditions. The shape and size of individual ChNTs were examined by transmission electron microscopy (TEM). Specific surface area (SSA) of nanotubes surface treated with a silane coupling agent and of pristine nanotubes in the bulk was determined by BET analysis of N-2 adsorption at 77 K. The theoretical SSA of a single nanotube and of nanotubes organized in a bundle was calculated as a function of nanotube geometrical parameters and the bundle size, that is, number of nanotubes in the bundle. A comparison of experimental and theoretically calculated SSA values indicated that nanotubes form bundles in the bulk. The characteristic bundle size in the bulk was estimated. The tendency of ChNTs to form bundles was also investigated in polar (ethanol) and nonpolar (xylene) solvents by measuring the complex viscosity behavior of the corresponding colloidal solutions. Viscosity measurements showed that nanotubes form bundles and that they are larger, consisting of more nanotubes, in nonpolar xylene than in polar ethanol. The tendency of ChNTs to aggregate in the bulk and in the solution was reduced by surface treatment of nanotubes with a silane coupling agent.

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Journal of Physical Chemistry C





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