QUESTION: We use cyanoacrylate adhesives in several assembly operations, but we are reluctant to use them for parts that might be used outdoors. What do you recommend?
ANSWER: For many years, cyanoacrylates were not recommended for outdoor applications where possible hydrolysis of the adhesive might occur. However, some modern formulations—particularly rubber-toughened adhesives—have proven to be highly resistant to thermal cycling and moisture. I would recommend these adhesives, with a warning to ensure that you have tightly fitting parts. The major limitation of cyanoacrylates is still their inability to fill large bond gaps.
QUESTION: We are using a room temperature-curing epoxy adhesive. My supplier keeps recommending an adhesive with a higher Tg. Can you please explain what that means?