Quantitative characterization of carbon nanotube turf topology by SEM analysis

A procedure has been developed to quantify various parameters that affect the mechanical stiffness of vertically aligned multi-walled carbon nanotube turfs from secondary electron images. A representative measure of density, tortuosity, and path connectedness is obtained from the images as these parameters are presumed to correlate with measured properties for this class of materials. Elastic moduli were determined using nanoindentation techniques. Experimental evidence indicates that an increase in turf density does not necessarily result in an increase in elastic modulus. Six turfs analyzed in this work along with four additional structures selected from a previous publication support the conclusion that an increase in density is not necessarily responsible for an increase in mechanical stiffness of a turf. Tortuosity and path connectedness tend to show more of a correlation with stiffness, though no direct correlation with these parameters was identified.