My question is specifically about outgassing of adhesives under vacuum. Does the adhesive eventually degrade (or vanish completely) due to outgassing? Even those adhesives classed as "low outgassing" under the ASTM E595 standard?

I understand why outgassing is bad. For example, it can contaminate other sensitive equipment (lenses, mirrors, etc.), and makes creating and maintaining high-vacuum environments challenging. However, for this question, these factors should be ignored.

Looking at the Torr Seal datasheet (or on a web page), I can see that one of the rows under "outgassing" says:

  • Temperature: 116°C (for 3 hours)
  • Cumulative Pumping Time: 43 hours
  • Outgassing Rate: $7\times10^{-5}$ with units given as Torr × liter per square centimeter per second

Let's take an example. If I have an environment with vacuum of $1 \times 10^{-4}$ Torr at 116°C and an exposed area of cured adhesive of 0.5 square centimeters, then the adhesive will outgass at $(7\times10^{-5} / 1 \times 10^{-4}) \times 0.5 = 0.35$ liters per second? Seems a lot. Does this mean the adhesive will very quickly "disappear" and the parts it is holding together will be unstuck. Or, will the outgassing rate reduce after some time (until it is negligible) and the adhesive will maintain its strength? Also, in the datasheet the outgassing rate decreases at a higher temperature (at 130°C it is $2\times10^{-6}$) which also does not make sense to me.

Answers in another question seem to suggest that the outgassing rate slows down, but I specifically want to know if the adhesive will degrade to the point of being useless. Any references to relevant literature / datasheets would also be appreciated.

I should mention that I hardly know anything about this area, so this question could be completely dumb.

Side question: What is the difference between the "for 3 hours" time vs the "43 hours" cumulative pumping time in the datasheet?



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