Basic ideas of microwave processing of polymers

The objective of this effort has been to investigate the relationship between polymer structure and microwave absorptivity. Dielectric loss factor, ε″, loss tangent, tan δ, and oscillator strength, (ε S −‐ ε ∞ ), were used to evaluate potential material processability under applied microwave radiation. Numerous polymeric materials varying in chemical and physical structures were irradiated in a low power (≤ 100W) electric field at 2.45 GHz. Electromagnetic radiation was applied as either traveling or resonant wave modes in cylindrical and rectangular waveguides. In general, heatability was found to be a direct function of the dielectric loss dispersion dependence on temperature and frequency. The dielectric loss factor obtained at low frequency measurements was found to be directly proportional to the heatability of polymers. A WLF plot was used to predict the shift of dielectric loss maxima into or out of the microwave frequency range.