Effect of Dissolved Oxygen (and Bubbles) on the Measured Permittivity of Geotextiles
Measurements are made of the permittivity in a heat set, nonwoven staple filament polypropylene as a function of the dissolved oxygen content (DOC) of the water. Vacuum deairing of the water to a DOC of 5 ppm or below insures that the measured permittivity will not be lowered by oxygen effects. Careful long-term measurements show that the measured permittivity is reduced very significantly if the DOC rises above 6 ppm. However as long as bubbles are not observed in the water, reasonably good values of the permittivity can usually be achieved, provided the measurements are performed rather quickly.