Elastomeri

Elastomers are polymers with viscoelastic properties that allow large, reversible deformation under stress and recovery once the stress is removed. They form flexible, elastic networks in which the chains can extend significantly before resisting further stretch. Most elastomers maintain their elasticity at ordinary temperatures because their glass transition temperature lies below room temperature. Crosslinks, whether chemical (through vulcanization or other curing) or physical, prevent permanent flow and give elastomers their characteristic resilience.

Elastomers can be natural or synthetic. The primary natural elastomer is natural rubber, mainly cis-1,4-polyisoprene. Synthetic elastomers include styrene-butadiene rubber (SBR), polybutadiene rubber (BR), nitrile rubber (NBR), neoprene (CR), polyisoprene (IR), and butyl rubber (IIR). Silicone elastomers (polydimethylsiloxane, PDMS) and fluorinated elastomers (FKM) offer high temperature and chemical resistance. Thermoplastic elastomers (TPEs) such as SEBS, SBS and thermoplastic polyurethanes (TPUs) combine elastomeric behavior with the processability of thermoplastics, enabling melt processing without permanent crosslinks. Conventional elastomers are produced by polymerization followed by curing: sulfur or peroxide vulcanization creates crosslinks that set a network, while some systems use addition or condensation cure chemistries.

Properties and applications vary with composition and crosslink density. Elastomers typically exhibit high elongation, good resilience, and varying chemical resistance, making them suitable for tires, seals and gaskets, hoses, belts, vibration dampers, medical devices, and consumer goods. Temperature range, compression set, abrasion resistance, and chemical exposure drive material choice. Environmental considerations include recycling and waste handling, with approaches ranging from mechanical reclamation and devulcanization to energy recovery where feasible.