What is the role of cross-links in thermosetting plastics?

The role of cross-links in thermosetting plastics is crucial for enhancing their tensile strength. Cross-linking refers to the formation of chemical bonds between polymer chains, which creates a three-dimensional network within the material. This network structure significantly increases the strength and rigidity of the plastic, making it more resistant to deformation under stress.

Thermosetting plastics undergo a curing process that causes these cross-links to form, resulting in a stable structure that does not soften upon heating. This characteristic is what allows thermosetting plastics to maintain their shape and mechanical properties even in high-temperature applications, making them suitable for a wide range of uses, from automotive components to electronic housings.

When examining the other options: increasing flexibility is typically associated with thermoplastics, not thermosetting plastics that become rigid upon curing. Lower durability contradicts the inherent strength provided by cross-linking, and facilitating recycling is generally a challenge for thermosetting plastics due to their hardened structure, making recycling complex compared to thermoplastics. Therefore, enhancing tensile strength accurately describes the critical function of cross-links in thermosetting plastics.