Which statement correctly classifies epoxy as a thermosetting polymer?

• A. Epoxy is a thermoplastic.
• B. Epoxy is a metal.
• C. Epoxy is a thermosetting polymer.
• D. Epoxy is an alloy.

Answer: (C)

Thermosetting polymers form a permanent, cross-linked network when they cure, so they become rigid and insoluble and do not melt upon heating. Epoxy resins undergo a curing reaction with a hardener that creates many chemical bonds between polymer chains, giving a three-dimensional network. That network prevents flow, making the material infusible and resistant to melting even at higher temperatures. Because of this permanent set after curing, epoxy is classified as a thermosetting polymer. It isn’t a thermoplastic (which softens and can be remelted when heated), and it isn’t a metal or an alloy.