The electric conductivity of polyethylene irradiated in atomic pile has been measured as the function of radiation dose, temperature, and humidity.
With the irradiation the surface conductivity of polyethylene increases from 1.7×10
-17 mho cm
-1 (no irradiation) to 4×10
-16 mho cm
-1 (1 unit) at 25°C. The conductivity σ of polyethylene is found to be related to the radiation dose
R by σ∝
R3/4 in the range
R=1_??_18 units and σ∝
R-2 in the range above
R=18 units.
Values of the apparent activation energy are calculated from temperature dependence of σ in 10
-4mmHg vacuum as 0.55 eV for non-irradiated samples, 1.98 eV, 1.6 eV and 2.2 eV for samples irradiated by 1, 18 and 72 units respectively.
With the increase of water vapor pressure, the increase of surface conductivity and the decrease of apparent activation energy are observed above 1 mmHg.
Experimental results are discussed with the mechanism of conduction.
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