Epoxy resin adhesives are supplied as two tubes that must be mixed before use because
Correct answer: D. the resin and the hardener react together to form cross links, setting the adhesive
- A. one tube contains the solvent that evaporates
- B. the two components are the same substance at different concentrations
- C. mixing lowers the temperature of the joint
- D. the resin and the hardener react together to form cross links, setting the adhesive
Explanation
Setting is a chemical reaction between the resin and a hardener that builds a rigid cross linked network, so the two must be kept apart until the moment of use. Because no solvent has to evaporate, epoxies set even in a sealed joint and bond metals, glass and ceramics strongly. Adhesives that set by solvent evaporation, such as rubber cement, work on a quite different principle.
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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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