What two categories can most plastics be placed in?

• A. Metals
• B. Ceramics
• C. Thermoplastics and Thermosetting plastics
• D. Polymers

Answer: (C)

Plastics are classified mainly by how they respond to heat and processing. The two broad categories you’ll see are thermoplastics and thermosetting plastics.

Thermoplastics soften when heated and can be melted and reshaped multiple times. This makes them easy to recycle and reform, which is why you often encounter them in pipes, fittings, and coatings used in building projects.

Thermosetting plastics, once cured or hardened, form a rigid, cross-linked network that doesn’t melt with heat. They keep their shape and strength under heat and are commonly used for structural adhesives, laminates, and protective coatings.

The other options don’t fit as a pair for most plastics: metals and ceramics are entirely different material families, and polymers is a broader category that includes both thermoplastics and thermosetting plastics, not the two distinct classes based on heat behavior.