Resisting high temperatures 13 December 2019

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.

Deputy Editor

Claire Aldridge Deputy Editor t: +44 (0) 1727 814 450


Having joined the magazine in 2012, Claire developed her knowledge of the industry through the numerous company visits, exhibitions and conferences she attended both in the UK and abroad.

Claire prides herself on keeping readers well informed and up to date with the latest industry news.