CHANGES IN THE SURFACE CONDUCTIVITY OF THE POLYVINYL CHLORIDE PRODUCT $sub 4$TROVIDUR$sub 4$ AFTER X-IRRADIATION WITH 1 TO 70 MEGARADS

The electric surface conductivity of the polyvinyl chloride plastic Trovidur was measured following energy doses of 1 to 70 megarads. A high-output x-ray machine served as the radiation source. At a relative moisture content of 75%, surface conductivity following irradiation was changed by 6 powers of 10 in comparison with the maximum before irradiation. The surface-conductivity value of a non-irradiated sannple was 10/sup -14/ohm/sup -1/ at a distance of 1 cm, with a measurement surface of 1.2 cm/sup 2/ and a test tension of 1000 volts. The relative change in surface conductivity varied with time, depending upon the dose, but only up to the 25th day. After that, it remained constant for the rest of the measurement period (75th and 150th day). In addition, constant values were also found following doses of more than 25 megarads, so that it was impossible to increase surface conductivity by applying larger doses. The increase in surface conductivity is interpreted as being the result of hydrophilization of the surface and of the formation of hydrogen chloride resulting from irradiation. Thus, the latter was traced quantitatively following doses between 28 and 130 megarads. Thirty days after irradiation the formation of hydrogen chloride was practically complete,more » and there was a linear connection between the total amount of hydrogen chloride developed and the dose. From this, a G value of 5.7 was determined. (auth)« less