Coating materials containing various types of conductive carbon black were prepared and coated on steel plate. Anticorrosive properties of this materials were investigated by salt spray test. The following results were obtained. (1) Anticorrosive properties of coated materials were influenced by the amount and the physical properties of carbon black added. (2) Carbon black having smaller specific surface area showed higher anticorrosive properties. (3) Coating materials having high anticorrosive properties showed large surface resistance. Accordingly, anticorrosive properties can be anticipated by measuring surface resistance of coating materials.

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Gel fraction and physical properties of polymers were measured after irradiation at various conditions for investigating the effect of temperature and atmosphere on the radiation induced cross-linkig and scission of polymers. The results were summarized as follows. The heating improved the efficiency of cross-linkig of high density polyethylene during irradiation. The rate of cross-linkig irradiated at 80 °C was found out to be second times of that of irradiated at 4 °C. Low density polyethylene and ethylene-vinyl acetate copolymer were irradiated by electron beam in nitrogen, air and oxygen. The measurement of gel fraction showed that the decrease in the cross-linking efficiency was in that order. The dose rate effect on the cross-linking efficiency was not observed when irradiation was performed under the dose rate ranging from 6 kGy/s to 600 kGy/s. The irradiation decreases the melt viscosity of polytetrafluoroethylene and electron beam had higher efficiency than γ ray.

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