Kristopher Wise, NASA


Kris Wise joined NASA Langley Research Center as a NRC Postdoctoral Research Associate after completing his PhD in Chemistry at the University of Oklahoma in 1999. He remained in the Advanced Materials and Processing Branch as a contractor (ICASE/NIA), eventually becoming a NASA employee in 2009. Over the past 15 years he has been fortunate to work with a number of talented experimental colleagues on a variety of materials development projects. His most recent work is focused on developing high volume fraction carbon nanotube composites for use in structural applications requiring high strength, lightweight materials.


Abstract:

Realizing the Promise of Carbon Nanotubes
Challenges, Opportunities, and the Pathway to Commercialization

One glance at a SEM image of a carbon nanotube paper or fiber is all that is required to realize that bulk carbon nanotube materials are incredibly structurally complex. Almost fractal-like, new and seemingly more complex structures become apparent at each level of magnification. The material is composed of bundles of tubes, which split and recombine or join other bundles. Furthermore, it is extremely difficult to assess the continuity of the bundles or individual tubes. The purpose of this Breakout session is, in essence, to answer the question: “What advances in theory and simulation methods are required to enable reliable simulations of bulk CNT materials?”

The (much easier) problem of predicting properties of single tubes or small bundles of tubes is largely solved. The predicted structural, mechanical, and electronic properties from accurate density functional theory calculations agree very well with experiment for these simplified model systems. Unfortunately, the measured values for these properties are much different in bulk CNT materials. Clearly we must find a way to represent the complexity observed at longer length scales if we hope to perform reliable simulations.

A few of the general questions to be addressed in this session include: (1) Given the extremely complex, inhomogeneous, multiscale structure of bulk CNT materials, what is the minimum volume of material that must be simulated in order to predict converged bulk properties? (2) What advances in theory and simulation will be required to model a bulk CNT system of this size? (3) Is there any prospect of getting more comprehensive experimental structural information than what is provided by current microscopy and scattering techniques? (4) What set of static and dynamic material properties should be used for verification and validation of predicted properties?