A general strategy for optimizing composite properties by evaluating the interfacial surface area of dispersed carbon nanotubes by fractal dimension

The amount and uniformity of carbon nanotubes (CNT) interfacial surface area are one of the key aspects limiting the usage of CNT in composite materials. We report a simple methodology to quantitatively determine the amount and uniformity of CNT interfacial surface area (i.e. level of space filling) using fractal dimension calculation based on scanning electron microscopy images. In this way, we clarified the relationship between the level of space filling of CNT interfacial surface area (fractal dimension) and the properties of rubber and plastic composites to directly relate the dispersion to the composite properties. Our results showed that the electrical conductivity and the tensile strength of composites increased exponentially and linearly with the increased level of space filling of CNT interfacial surface area, respectively within our experimental range. Importantly, these relationships were general, that is, independent of dispersion methods, CNT concentration, CNT types and kinds of matrix (such as rubber, plastic). Taken together, these results serve as a general map to increase the level of space filling of interfacial surface area through controlling various dispersion conditions during CNT dispersion, which is of great significance to the fabrication of CNT composites. (C) 2019 Elsevier Ltd. All rights reserved.