Gamma radiation effects on PVC [polyvinyl chloride] compounds

There exists a definite need for understanding the effect of nuclear radiation on the electrical properties of materials used to insulate electrical equipment. Polyvinyl chloride (PVC) polymers and their compounds are a favorite insulating material that may be considered for application in nuclear installations. Historically, this type of material has not been studied in depth under gamma irradiation. Some limited work has been done on the changes produced under these conditions using direct-current measuring techniques. In the study reported in this paper, these effects were evaluated under conditions that are of great practical interest. For this purpose, three compounds of PVC were selected. They reflected three levels of hardness most commonly found in these materials. For this reason, each contained a different amount of plasticizer. The greater the plasticizer content, the softer is the final material. These three samples were subjected to 105, 106, and 107 rad coming from a linear accelerator as bremsstrahlung produced by gemstones. These X rays had energies in the vicinity of 5 MeV. The effect of this type of irradiation was simulated mathematically using Lambert's law and a modified Euler iteration as a method of computation. The results of this computerized simulation were used as a means to predict subsequent empirical investigations of the effect of this type of radiation on the dielectric properties of the three samples