One of the factors influencing the chemical resistance of epoxy resin is the hardener used in their curing. To demonstrate this, three chemically different types of hardeners (anhydride, amine, boron fluoride complex) were used to cure a conventional liquid epoxy resin. All systems were checked for changes in flexural strength after a six-month immersion period in various chemicals at room temperature. Media in which tests were made include sodium chloride, sodium bisulfite, sulfuric acid, hydrochloric acid, nitric acid, glacial acetic acid, caustic soda, sodium carbonate, ammonia solution, and four weak organic solvents. In addition, samples were also placed in water at room temperature as well as boiling water for a six-month immersion period.
Diaminodiphenyl sulfone gave resins the best over-all chemical resistance. Weak solvents, such as hydrocarbons, alcohols or glycols, affected all systems only slightly. Anhydride - cured systems exhibited better resistance to diluted acids while amine-cured systems showed better resistance to diluted bases. 6.6.8
