Effect of diamond-like carbon thin film deposition on the resistance of polycarbonate to radiation-induced degradation

The effects of high-energy gamma irradiation on the characteristics of polycarbonate specimens (Lexan plate) deposited with a thin film of diamond-like carbon (DLC) were investigated. A plasma enhanced CVD method was adopted in depositing a thin DLC film on the polycarbonate specimens. Both specimens, with DLC film and without it, were exposed to the gamma radiation emitted from a Co-60 source to the level of 10(6) rad for comparing their properties. The concentration of free radicals in the undeposited specimen rapidly decreased to 4.4% of the initial value, while that in the specimen deposited with DLC him remained at 60%. It is suggested that DLC inhibits the oxidation reaction between free radicals and oxygen in the surrounding air. This study shows experimental evidence that the resistance to radiation-induced oxidation of a polymer can be enhanced by depositing a thin layer of DLC. (C) 2000 Elsevier Science Ltd. All rights reserved.