Measurement of Bound and Free Moisture in Organic Materials by Microwave Methods

摘要

Bound and free moisture can be classified by energetic, structural, or operational schemes. We discuss these schemes and consider four methods (dynamic dielectric thermal analysis, microwave attenuation analysis, near-infrared reflectance analysis (NIRA) and nuclear magnetic resonance (NMR) spectroscopy) that have been suggested for distinguishing between bound and free moisture in organic materials. This report describes the microwave attenuation method. The theoretical basis for using microwaves for this purpose is developed. We show that microwave measurements can be used to measure the moisture in triaminotrinitrobenzene (TATB) using a microwave network analyzer down to 0.04% H sub 2 O. The design of the apparatus necessary to extend these measurements to lower moisture content limits is mentioned. As part of this study, we measured the dielectric properties of TATB for the first time. We found that the dielectric constant epsilon' for TATB was 4.00 +- 0.01.