Elásticos

Elásticos are a class of polymers characterized by high elasticity: they can undergo large reversible deformations under load and recover their original shape when the load is removed. They behave as viscoelastic materials, storing mechanical energy and damping motion. The term encompasses natural rubber and a wide range of synthetic polymers known as elastomers.

Natural elastomers come from latex of certain plants, most notably Hevea brasiliensis (natural rubber). Synthetic elastomers include styrene-butadiene rubber (SBR), nitrile rubber (NBR), neoprene (CR), silicone elastomers (VMQ), EPDM, and polyurethane elastomers. Most elastomers form a three- dimensional crosslinked network after curing, which fixes their shape and resists flow. Vulcanization with sulfur is the most traditional method, while other crosslinking chemistries are used for different properties.

Key properties include high elongation at break, low modulus at low strains, good energy absorption, and temperature dependence governed by the glass transition temperature. Resistance to aging, oxidation, ozone, and UV light varies by formulation. Some elastomers are oil, solvent, or heat resistant; others are highly elastic but brittle at low temperatures. Processing methods include extrusion, molding, and calendaring to form sheets, tubes, films, fibers, or molded parts.

Applications span tires, seals, gaskets, vibration dampers, hoses, medical devices, consumer goods (such as rubber bands and hair elastics), and flexible components in electronics and automotive industries. The development of Goodyear's vulcanization in the 19th century dramatically expanded their use. Today, the choice of elastomer and cure system reflects the required temperature range, chemical exposure, mechanical load, and durability, balancing elasticity, strength, and resilience.