élastique

Élastique is a term used to describe materials that can stretch under force and return to their original shape when the force is removed. In common usage it often refers to elastic bands, but in materials science it designates elastomers—polymers with high elasticity that can undergo large reversible deformations.

Most elastomers are hydrocarbon polymers. Natural rubber is polyisoprene obtained from Hevea brasiliensis. Synthetic elastomers include styrene-butadiene rubber (SBR), nitrile rubber (NBR), neoprene, silicone, and polyurethane. Elastic behavior arises from a three-dimensional network of crosslinked polymer chains; vulcanization, typically with sulfur or peroxides, converts soft polymers into durable, resilient materials.

Key properties include high elasticity, the ability to recover shape after large strains, and viscoelastic behavior that leads to energy dissipation as heat. The elastic modulus depends on temperature and rate of deformation; higher temperatures generally reduce stiffness, and repeated loading can cause aging or degradation.

Common applications span everyday and industrial uses: elastic bands and clothing elastics, rubber bands for bundling, tires and automotive seals, medical tubing and devices, footwear components, and various consumer products requiring stretch and resilience.

Etymology and notation: the word elastic derives from Greek ēlastikos, meaning capable of springing back, via Latin elasticus. In French, élastique follows the same lineage and is used for both the material class and for everyday elastic bands.