Elastomers represent a distinct category of polymer materials renowned for their exceptional elasticity. Unlike plastics and other polymer types, elastomers possess the remarkable ability to stretch extensively and then revert to their original form without sustaining permanent deformations. The term 'elastomer' originates from 'elastic polymer,' highlighting their primary characteristic: elasticity.
Operating above their glass transition temperature, elastomers are amorphous polymers, ensuring flexibility and malleability at ambient conditions. This flexibility is pivotal across various domains, ranging from household products to critical industrial components. Unlike rigid plastics, elastomers can undergo substantial reversible deformation when subjected to stress, owing to their molecular arrangement, particularly the elongated, coiled polymer chains that elongate under tension and contract upon release.
Elastomers are polymer materials characterized by their viscoelastic nature, which denotes the combination of both viscosity and elasticity. The chemistry underlying elastomers is centered around their polymer chains and the cross-links that connect these chains together.
Polymer Chains
At the core of any elastomer lies its polymer chains. These chains, elongated and coiling in structure, consist of repetitive units known as monomers. The composition of these monomers and the arrangement of the polymer chains dictate numerous properties of the material. For instance, natural rubber primarily comprises isoprene (cis-1,4-polyisoprene), whereas synthetic rubbers such as SBR (styrene-butadiene rubber) are copolymers derived from styrene and butadiene monomers.
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