Effects of Water on Epoxy-Resin Systems.

The effect of continuous immersion in water on the tensile strength, tensile elongation, tensile modulus, flexural strength, flexural strain, and bond strength of five different epoxy-resin systems was evaluated. The water absorption of the five systems was also obtained. One of the systems will meet Federal requirements for epoxy resins and another contains the same system but includes sand as a filler. All of the physical properties of these two systems were deleteriously affected by storage in water and, therefore, the systems should not be used when the cured systems will be subjected to immersion in water for periods longer than 1 month. In addition, every effort must be made to protect these two systems from undue exposure to water. The test results also indicate that the use of a modifier in proper amounts will produce a large increase in strength and elongation and a large decrease in tensile modulus and water absorption. Two of the modifiers tested, polymide and amidopolyamine, produced epoxy-resins systems which were not deleteriously affected by immersion. The testing errors determined in this investigation are given as a guide for testing the engineering properties of epoxy-resin formulations. Author