Master Bond, a manufacturer of epoxy adhesives, sealants, coatings, potting, and encapsulation compounds, recently tested a range of epoxy compounds for their ability to withstand prolonged exposure to sulfuric acid.
Most typical epoxy systems under these harsh conditions would degrade over time. However, Master Bond’s tested compounds maintained excellent hardness when immersed in a solution of 98% sulfuric acid over a span of six months.
In this experiment, the compounds tested were two component epoxy systems with good overall chemical resistance, including EP62-1HT, EP62-1BF, EP41S-5, EP21ARHT, EP35SP, and a generic epoxy adhesive for comparison. A pre-measured casting weighing a few grams of each product was created. Once the cured samples were ready and initial weight was recorded, we submerged them in a 98% solution of sulfuric acid.
A change of less than +/-2% can be considered excellent, especially since this test may be more rigorous compared to actual service conditions. Although Master Bond plans to carry on with these weight recordings over a longer period of time, here are the percentage of weight change after the first six months of testing.
The acid-resistant epoxies:
EP62-1HT: Offers excellent resistance to harsh chemicals, particularly to acids. This two-part epoxy has long pot life at ambient temperatures. It is ideal for bonding and coating, and offers a reliable electrical insulator. It is serviceable from -60° to +450° F. Tg 150-160° C. Shore D hardness 80-90.
EP62-1BF: Cures rapidly at moderate elevated temperatures. This two-part epoxy offers superior resistance to harsh chemicals and has a long pot life at ambient temperatures. It serves as a reliable electrical insulator. It is serviceable from -60° to +500° F. Tg 170-175° C. Shore D hardness 80-90.
EP41S-5: Offers exceptional chemical resistance to solvents, bases, acids, alcohol, and fuels. Withstands exposure to methylene chloride, phenol (10%), and nitric acid (30%). It can be used for potting/encapsulation, as well as for coating tanks, pumps, and vessels. Formidable physical strength properties. It is serviceable from -80° to +450° F.
EP21ARHT: Exceptional acid resistance, cures at room temperature, and provides good flow properties. There is low shrinkage upon cure and this epoxy is 100% reactive. Withstands 1,000 hours 85° C / 85% RH. Adheres well to metals, glass, ceramics, rubbers, and plastics. Serviceable from +400° F. Shore D hardness 80-90.
EP35SP: A high-temperature resistant epoxy system that withstands exposure to aggressive chemicals. It offers a paste viscosity — 100 to 50 mix ratio by weight. The service temperature range is -80° to +550° F. Excellent compatibility with filament winding and bonding composites.