Porosity Level Estimation in Polymer Composites using Microwaves
The ability of microwaves to monitor variations in porosity level of composite samples is studied. Measurements of several carefully prepared samples with different air volume fractions are performed at the frequency range of 8.2-18 GHz. The measurement results indicated that there is an excellent sensitivity to small differences in porosity level. A two-phase mixing model used for predicting the dielectric properties as a function of porosity level shows good agreement with the measured results. This model may be used to closely predict the amount of air content from measured dielectric properties. Changes in clustered (local) porosity are studied experimentally as well. Microwave scan of specially prepared samples with about 5 percent change in air content (local porosity variation) are also presented.
S. D. Gray et al., "Porosity Level Estimation in Polymer Composites using Microwaves," Materials Evaluation, vol. 53, no. 3, pp. 404-408, American Society for Nondestructive Testing, Inc., Mar 1995.
Electrical and Computer Engineering
Keywords and Phrases
Composite Materials; Dielectric Materials; Dielectric Properties; Estimation; Mathematical Models; Monitoring; Permittivity; Polymers; Porosity; Sensitivity Analysis; Volume Fraction; Wave Transmission; Air Volume Fraction; Dielectric Constant; Local Porosity Variation; Nondestructive Inspection; Polymer Composites; Porosity Level Estimation; Two Phase Mixing Model; Microwaves
International Standard Serial Number (ISSN)
Article - Journal
© 1995 American Society for Nondestructive Testing, Inc., All rights reserved.