Thermoplastic adhesives such as hot melt glue set by
Correct answer: A. cooling and solidifying, with no chemical change
- 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.
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About Adhesives
Adhesives are substances that join surfaces through bonding, wetting and hardening, and may be natural or synthetic. The topic covers starch, dextrin, casein, animal glue, rubber-based adhesives and polymeric resins, together with the effects of viscosity, setting time, temperature, moisture and surface condition on adhesive strength.
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