Measurements of the Thermal Diffusivity Tensor of Polymer–Carbon Fiber Composites by Photothermal Methods

The thermal diffusivity tensor of a polymer-carbon fiber composite with unidirectionally distributed fibers has been measured using a modulated photothermal mirage device. The thermal diffusivity along the fibers is kn = 6.0 + 0.5 mm2 • s-1, that perpendicular to the fibers is k± =0.35 + 0.05 mm2-s~1, and that perpendicular to the sample surface is kz = 0.40 ± 0.15 mm2-s~1. These results have been confirmed by independent measurements on the sample by other laboratories using three other different photothermal techniques. A previous claim on anomalous results found on this sample (ky