Effect of Absorbed Water upon the Dielectric Properties of Certain Acrylic Ester Polymers

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Abstract
The effect of absorbed water upon the dielectric properties of polymethylmethacrylate, polyethylmethacrylate, and polyethylacrylate is experimentally investigated over a temperature range from 70°C to —195°C and at frequencies between 100 cps and 200 kc. It is found in each case that the absorbed water gives rise to a discernible loss index peak in the low‐temperature region (0° to —100°C). The 2.1% water absorbed in a specimen of polyethylacrylate acts as a plasticizer, apparently lowering the glass transition by 5C°. The facts that the apparent activation energy and the temperature location of the water induced peak changes with variations in the polymeric structure indicate that the induced loss peak is not to be identified with the loss peak found in ice, and furthermore suggests that the dielectric method can be employed to learn more about the water—polymer complex which is formed when water is absorbed into a polymer.