Many Master Bond epoxy systems are formulated with superior chemical resistance. In the lab we continually test our materials by exposing them to specific chemicals over a long period of time. A common way of testing chemical resistance of an epoxy is immersing a sample in a chemical and measuring its change in weight over time. A significant loss or gain in weight would indicate a decreased ability of a material to stand up to chemical exposure. These tests allow us to more accurately recommend the right adhesive based on specific application requirements.
In this experiment, we’ve focused on testing our epoxies for their resistance to Skydrol. The compounds we used for testing are two component epoxies and one component UV curing systems with good overall chemical resistance: EP41S-5, EP62-1HT, EP42HT-2AO-1 Black, and UV26 . A few thin castings, roughly 2 inches in diameter and around 0.125 inches thick, were made for each product and cured in accordance to their specifications. Once the cured samples were created and initial weight was recorded, we submerged them in the hydraulic fluid, Skydrol. Then we continued recording weekly weight measurements. Although we plan to carry on with these weekly weight recordings over a longer period of time, below you will see the results from the first 37 weeks of testing, demonstrating the percentage of weight change over time.
In general, a swelling of less than 1% can be considered excellent, especially since this test may be more rigorous compared to actual service conditions. It is also worth noting that in the context of a bonded joint or a potted assembly the exposure to fuels might not be as severe or direct, as in the above test conditions.
Please note, when choosing an epoxy for an application where the resistance to fuels is critical, many other factors must be considered in addition to the chemical resistance. Each of the products in the chart above offers a distinct set of performance properties. For example, if thermal conductivity is needed, EP42HT-2AO-1 Black may be a good option. If a fast cure is required and there is full access to a light source, UV25 can be considered.
Disclaimer: The findings in this article are not meant to be used for specification purposes.
Skydrol Resistant Adhesives
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EP41S-5 Excellent chemical resistance to solvents, bases, acids, alcohol and fuels. Withstands exposure to methylene chloride, phenol (10%) and nitric acid (30%). Well suited for coating tanks, pumps and vessels. Moderate viscosity with good flow properties. Can be used for potting/encapsulation. Formidable physical strength properties. Serviceable from -80°F to +450°F. |
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EP62-1HT Superior resistance to harsh chemicals, particularly to acids. Two part epoxy has long pot life at ambient temperatures. High bond strength properties. Ideal for bonding and coating. Good flow. Reliable electrical insulator. Serviceable from -60°F to +450°F. Tg 150-160°C. Shore D hardness 80-90. |
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EP42HT-2AO-1 Black Good heat conduction. Serviceable from 4K to +400°F. Resists water, oils, fuels. Excellent dielectric properties. Enhanced dimensional stability. Castable up to 2-3 inches thick. Low shrinkage upon cure. Good flow. Meets NASA low outgassing standards. |
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UV26 Specialty type UV curable adhesive with very fast curing time and high thermal stability. Its glass transition temperature is 160 to 170°C and its service temperature range is -60°F to +500°F. UV26 resists acids, bases, fuels, and many aggressive solvents. |
