THERMAL-DIFFUSIVITY MEASUREMENT OF PAPERS BY AN AC JOULE HEATING METHOD

The thermal diffusivity (alpha) of paper, a porous and thin material, was determined by an ac Joule heating method developed in our laborato ry. With this technique the thermal diffusivity of paper was obtained directly with high reproducibility without the need for special prepar ations, such as the black coating, required in conventional methods. T he thermal diffusivity (alpha) of paper was obtained as a function of temperature and the apparent density (rho). The apparent thermal condu ctivity (lambda) of paper was calculated from alpha, rho, and the heat capacity at constant pressure (C-p): alpha decreased with increasing apparent density, but lambda did not show a density dependence. (C) 19 98 SCI.