elastomer

An elastomer is a polymer with the property of elasticity: it can be stretched or compressed and return to its original shape once the deforming force is removed. This behavior results from long chain molecules with limited but sufficient crosslinking, which creates a flexible network that resists flow at room temperature but allows large reversible deformations. Elastomers are viscoelastic, exhibiting both elastic and viscous responses, and typically have a glass transition temperature well below ambient, so they remain rubbery in use.

Elastomers occur naturally, most notably natural rubber from Hevea brasiliensis (polyisoprene). They are also synthesized in many forms, including styrene-butadiene rubber (SBR), polybutadiene, nitrile rubber (NBR), neoprene, silicone, and fluorinated elastomers. Thermoplastic elastomers (TPEs) combine elastomeric behavior with thermoplastic processing. Most conventional elastomers are crosslinked by vulcanization (often with sulfur) to form a three-dimensional network that enhances elasticity, heat resistance, and mechanical strength; vulcanization reduces tack and prevents creep.

Key properties include high elongation at break, good resilience, and damping, with a modulus significantly lower than rigid polymers. Chemical resistance, temperature tolerance, and oil resistance vary by formulation. Processing methods include extrusion, molding, and calendering; post-processing crosslinking or dynamic vulcanization may impact performance.

Applications are widespread: tires, seals, gaskets, hoses, vibration dampers, medical devices, and flexible seals. Environmental considerations include aging, ozone resistance, UV stability, and recyclability; some elastomers are devulcanized or thermally recycled, while others are used in energy recovery.