Understanding low outgassing adhesives

Cure for outgassing
When selecting adhesives for low-outgassing applications, engineers often don’t pay much attention to cure schedules.

That’s understandable since so many modern adhesive formulations do indeed cure well at room temperature, developing better than adequate mechanical and physical properties for their intended use. Yet the addition of a heat cycle will optimize a host of desirable physical properties— low outgassing among them. With adhesives, in other words, it’s often the case that a room temperature cure is good, but a heat cure is better.

In low-outgassing applications, heat can even be essential. Heat tends to improve the crosslink density, which in turn limits outgassing. We’ve seen cases where individual adhesives did not pass ASTM E595 when cured at room temperature but passed after a heat cycle. For that reason, we recommend the addition of a heat cycle for applications where outgassing performance is critical. A typical cure schedule would be room temperature overnight, followed by 2–5 hours at 60-80°C.