A composite index to quantify dispersion of carbon nanotubes in polymer-based composite materials

Several methods with various levels of sophistication exist to quantify dispersion of carbon nanotubes (CNTs) in a polymer matrix, such as the ASTM D2663 standard that is often used in engineering practice. However, most methods are limited by their accuracy, complexity of implementation, and scalability. In this paper, we present a new technique and index to quantify dispersion of CNTs in a composite material. The technique is partially based on a quadrat method, and takes into account the dispersion and agglomerate size distribution of the CNTs. This index is benchmarked against the ASTM index using computer generated images and images experimentally obtained from thirty CNT composite material specimens with different CNT loading rates up to twenty volume percent. The new index is shown to be more versatile and reliable than the ASTM index. It is easily implementable in engineering practice as opposed to other more sophisticated techniques available in the literature.