Microwave dielectrometry measurements of glass reinforced polyester resins

This study describes measurements of dielectric constant as a function of g lass reinforcement concentration in polyester resins to use as a control pa rameter for online process monitoring. Microwave interferometers were const ructed in the X and V bands at 9.35 and 60 GHz in both homodyne and heterod yne configurations to measure the phase difference associated with the mate rial. This phase difference is then used to calculate the real part of the dielectric constant from the index of refraction at a microwave frequency. The homodyne X and V band measurements yielded a linear relationship betwee n phase difference and glass concentration. Heterodyne V band measurements produced a nonlinear relationship. Further investigation into the microscop ic interactions between the reinforcement particle and the polymer resin is necessary to determine how different concentrations affect the bulk macros copic material properties.