Effect of temperature and water salinity on hydrophobicity of epoxy resin

The effects of temperature and water salinity on the hydrophobicity of epoxy resin, which is used as resin for molds of glass-fiber reinforced plastics, is investigated. The hydrophobicity of epoxy resin was determined by measuring the contact angle using a droplet of distilled water. The weight change of the specimens was also measured. The relationship between the changes in the hydrophobicity of the specimens and the deposits on the surface of the specimens after aging was analyzed by XPS. Aging of epoxy resin was attained by immersing it for up to about 1000 h in saline water solutions in the range 0.005-100 mS/cm and exposure to air at 0, 25, 46, 75 and 98/spl deg/C. After aging, the contact angle of the specimens was periodically measured in air at room temperature for up to about one year to study the recovery of hydrophobicity.