epoxy weakens at moderately high temps?

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Well-Known Member
Sep 5, 2003
Midwest USA
I have data sheets for T-88 ,and, likewise other epoxies in common use in homebuilts. I am generally unimpressed by their performance... strength, durability, high/low temp resistance, environmental resistance, etc

Aerospace grade multi-part epoxy resins [low viscosity laminating resins, 'pastes', primers, potting/filler-pastes, films etc] are considerably higher-performing than commercial grade or marine grade epoxies... and are more expensive. However properties really are genuinely amazing and very consistent within storage limits and proper usage/prep.

Some 2-part laminating and paste room-temp-cure epoxy resins can have service temperatures -65F to +400F [service = 500-to-1000-PSI lap shear]… but have toughness issues to deal with [both temperature extremes].

Also 'be wary'... ALL epoxies change nature [strength, toughness, service temp range, etc] as they 'age'... with 20-year[+/-] typical for service-age limit for a variety of reasons. This is why there are other resins formulated for composite primary structure that mandate heat and high pressure during cure and have different chemistries. Gag-me.

For comparison/info...

3M Aerospace. https://www.3m.com/3M/en_US/aerospace-us/ [structures tab]
Solvay [Cytec] https://www.solvay.com/en/solutions-market/aerospace
Henkel [Hysol, Loctite] Aerospace - Henkel Adhesives (henkel-adhesives.com)

I just realized that this is a tiny drop in the bucket of info... that could be meaningless without a lot of study and discussion.

NOTE. The MIL-jet I work on primarily, was designed in the 1950s and had design static temperature range of -65F to +160F and was all silver to reflect heat from nuclear flash. Real-world environments have been documented from -100F to +180F... and 'nuclear flash/heat' can instantly raise hull temperatures to +800F for a short duration [20-30 seconds] due to dark-gray camo paint... that will simply burn-off.
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