The objective of this research is understanding the role and mechanism associated with thermal expansion within CNCs and CNC composites. The coefficient of thermal expansion (CTE) is important to a variety of fields; for example, electronics where thermal mismatches cause failure of components such as electrodes, and composites where thermal mismatches cause dimensional shape changes. Because CNCs have been used as substrates for electronics and as fillers in composites, accurate determination of CTE of CNCs, CNC composites, and the mechanisms for thermal expansion are important. Researchers have developed a unique characterization technique using polarized light imaging correlation that allows more accurate CTE measurement of thin transparent CNC films. Thin films with 100 percent CNCs have been shown to be metal-like in their CTE (i.e. 25ppm/K). By using shear based casting techniques it is possible to get preferential alignment of the CNCs, and in the direction of CNC alignment it is possible to get ceramic-like CTE (i.e. 9 ppm/K). This was the first study of its kind to use polarized light imaging to measure displacements based on thermal changes.