What is the key characteristic of thermosetting polymers?

The key characteristic of thermosetting polymers is that they cannot be remolded once set. This property stems from the chemical structure and bonding that occurs during the curing process. When a thermosetting polymer is heated and cured, it undergoes a chemical reaction that creates a three-dimensional network of cross-linked polymer chains. This network structure gives thermosetting plastics their rigidity and durability, and once they are set in this form, heating them again will not allow them to be reshaped or remolded. This is in contrast to thermoplastics, which can be melted and reformed multiple times.

The inability to remold thermosetting polymers makes them ideal for applications requiring high strength, stability, and resistance to deformation under heat or stress, such as in electrical components and structural materials. This characteristic directly differentiates them from other types of polymers that maintain flexibility or can be reshaped upon heating.