THERMAL AND NONTHERMAL INTERACTION OF MICROWAVE-RADIATION WITH MATERIALS

Industrial use of microwave radiation as an alternative to conventional thermal heating has generated interest recently mainly because of the drastic reduction in the processing ti me. In spite of its wide application, its chemical mechanism of interaction with materials has not been well understood. The current debate on the alternative use of microwave radiation to conventional thermal heating is on the involvement of a ''microwave specific effect'' other than the well accepted dielectric heating. There are reports of various reactions which show similar kinetics under both microwave and thermal methods at similar temperatures suggesting simple dielectric heating of materials by microwaves. There are also reports which show a clear reaction rate enhancement under microwave radiation compared to the thermal method under similar reaction conditions and temperatures indicating a ''microwave specific effect'' other than the simple dielectric heating of materials. This paper will discuss the above conflicting results reported in the literature.