Abstract
Dielectric constant ε′ and dielectric loss ε″ at microwave frequencies were determined for hand-sheets of various densities prepared by changing freeness, mesh size for fractionation and pressure for wet pressing. Both ε′ and ε″ at 4.0 GHz increased linearly with increasing density. Empirical formulae ε′=0.531+3.07 ρ and ε″=-0.098+0.619 ρ for handsheets of hardwood pulps were obtained for densities between 0.5 and 1.0g/cm3. The correlation coefficient between ε′ and ρ and between ε″ and ρ were 0.994 and 0.984, respectively. These formulae were interpreted on the basis of proportionality of density to the number of dipoles per unit volume in the paper sheet.
