Abstract
The moisture absorption characteristics of a novel crosslinkable polyether of relatively low polarity have been determined. The relative permittivity (dielectric constant) was found to be 3.2 at 1 kHz and 22°C. This value is compared with that obtained for other polymers. Changes in relative permittivity following exposure to moisture were compared with corresponding changes in the epoxy resin system Epikote® 828/MPD. The polyether absorbs much less water than the epoxy, and the relative permittivity changes less during exposure to moisture. A Clausius-Mossotti calculation has been used to examine the free state polarisability of the absorbed water. The analysis suggested that absorbed moisture plasticises the polyether, producing a greater change in overall dielectric response than could be attributed to the water alone. In contrast the increase observed in epoxy resins is less than expected from the mass of moisture absorbed.
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