The goal of this research is to develop a working understanding of microwave interactions with materials that will enable targeted industrial operations to apply microwave technologies to product manufacturing. The PIs plan the: (1) development of experimental procedures to obtain quantitative, in situ processing data on microwave interactions with materials in forms ranging from liquid to solid states; (2) identification of the mechanisms leading to observed differences between conventionally and microwave-processes samples; (3) production of samples that illustrate the differences between conventional and microwave processes; (4) data to serve as a basis for scale-up of microwave equipment for continuous and/or large batch processing; (5) assessment of temperature measurement techniques used in microwave processing; and (6) technology transfer in this area. This grant is for the completion of a project in progress in which the primary chemical systems under study are sol-gel derived silica. A silicon alkoxide precursor mixed with water and alcohol is being reacte d under the influence of both microwave and conventional heating techniques. Using Fourier transform infrared (FITR) and Raman spectrosopies, among other methods, for measuring the effects of microwave irradiation during processing --- a cavity ring-down apparatus outfitted with a microwave applicator, the effects of microwave energy and conventional heating on molecular bond formation/dissociation of each individual component of the sol are being examined. Dielectric property measurements are being performed on the sol and its components at microwave frequencies (and temperatures) over which the reactions take place. This approach enables a correlation between dielectric properties, the molecular/phase changes, reaction extent and the resultant properties of the chemicals/materials during the various stages of microwave processing. Microwave irradiation increases significantly the rates of reaction during sol-gel processing. Experiments are designed to determine the extent to which microwave energy affects each of the processing steps.
