Polymers that cannot be remelted because they have cross-links between chains are known as:

• A. Thermosetting Polymers
• B. Thermoplastics
• C. Nylon
• D. Acrylonitrile Butadiene Styrene

Answer: (A)

Crosslinked networks lock polymer chains together, forming a rigid three-dimensional structure that cannot flow. When the polymer is cured, covalent bonds link the chains, turning it into a thermosetting material. Those permanent bonds mean heating won’t melt the material into a liquid you can reshape; it may soften or burn, but it won’t remelt and flow like a plastic.

In contrast, thermoplastics have little to no permanent crosslinks, so heating allows the chains to slide past one another and the material to melt and be reshaped. Examples like nylon and ABS are thermoplastics, which is why they can be remelted and remolded.