Thermoplastic adhesives such as hot melt glue set by
- A. cooling and solidifying, with no chemical change
- B. reacting chemically with the surface
- C. absorbing water from the air
- D. releasing carbon dioxide
Explanation
The adhesive is applied molten, flows into the surface irregularities and then simply freezes as it cools, so the change is physical and reheating the joint softens it again. This makes such adhesives quick and convenient but unsuitable where the joint may become warm. Thermosetting adhesives such as epoxies form permanent cross links instead.