Dielectric properties of polybutadiene and its reinforced composites at room and elevated temperature

With many dielectric materials the dielectric constant does increase with temperature; this is due to the softening of the polymeric network. Greater rotation of the molecular dipole at elevated temperature has been attributed to friction increase, which, in turn, increases its loss factor. Loss factor, a product of dielectric constant and loss tangent, is proportional to the microwave energy dissipated in the material. The equation relating the loss factor and dissipated energy per unit volume is given by: W̅ (energy dissipated/volume) = constant Xε"fE2 where ε": loss factor f: frequency E: field intensity.