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Master Bond Supreme 121AO is a NASA low outgassing approved epoxy suitable for bonding, sealing and potting applications. Featuring a high glass transition temperature of 200°C – 210°C, it resists temperatures up to 550°F (288°C).

Master Bond points out that this system exhibits an element of toughness and is not as stiff as conventional epoxies that withstand extreme temperatures. Supreme 121AO has a strength profile with a tensile modulus of 750,000 psi to 850,000 psi at room temperature and a compressive strength of 26,000 psi to 28,000 psi. Its thermal conductivity is 4 – 5 BTU•in/(ft2•hr•°F), and it is also electrically non-conductive.

Shrinkage upon cure is also exceptionally low. This system not only withstands thermal cycling and mechanical stresses, but also resists many chemicals, including water, oils, fuels, acids and bases. As a result, Supreme 121AO can be used in aerospace, electronic, optoelectronic and OEM applications.

This two part epoxy has a mix ratio of 100 to 80 by weight. The viscosity of the mixed compound is 10,000cps – 25,000cps, making it readily pourable for potting and casting. It has a long working life after mixing of 2 – 3 days, for a 100g batch. The recommended cure schedule is 1 – 2 hours at 200°F (93°C) followed by 3 – 4 hours at 250°F (121°C), and then 4 – 6 hours at 300°F (149°C). Additional post curing at 350°F (176°C) for 2 – 4 hours will further enhance product properties.