Electrical conductivity of nickel nanostrand polymer composites

The electrical conductivity properties of nickel nanostrands in polymer composite systems are investigated and characterized. Recently developed nickel nanostrands feature a three-dimensionally interconnecting and branching nanostructure that is shown to be highly effective at imparting electrical conductivity in polymer composites. A systematic investigation of material behaviors is undertaken, with results that have been or will be published in a series of journal articles. The content of the studies that form these articles is given herein as the core content of this work. The first study investigates the basic electrical and mechanical properties of nanostrands in a single polymer system. Key results indicate a strong dependence of conductivity properties on processing conditions, volume fraction of conductor, and sample geometry. Mechanical properties are not significantly altered by the presence of nanostrands. The dispersed nanostrand structure is next investigated through the development of statistical topology tools that can quantify nanostrand dispersions and correlate them to the electrical resistivity of composite films. Quantification of the dispersed nanostructure is a significant improvement over common literature approaches. The next step tests full percolation characterization across multiple polymer systems, and indicates a strong dependence on electrical resistivity between polymer types. Polymer constituent properties are found to be poor predictors of nanostrand composites conductivities, though further testing of addition metrics is expected to bring improved correlation. The concluding investigation seeks electrical conductivity percolation models for nanostrand composites. Existing models show only moderate accuracy, and a newly developed combined percolation tunneling approached is suggested for improved fit to measured conductivity.