ethylenebutylene

Ethylenebutylene, often referred to as ethylene–butylene rubber (EBR), is a synthetic elastomer produced by the copolymerization of ethylene with butene. It is commonly described as poly(ethylene-co-butene), a random copolymer whose mechanical properties can be tuned by adjusting the ethylene to butene ratio and the level of crosslinking. The resulting material is flexible at low temperatures and exhibits good elasticity and resilience.

Production and structure

EBR is formed by polymerizing ethylene and a C4 olefin such as 1-butene using Ziegler–Natta or metallocene catalysts. The process yields a rubbery, amorphous copolymer with a relatively low glass transition temperature. Vulcanization or peroxide curing is used to impart set and improve thermal and chemical resistance. The vinyl content of the copolymer influences hardness, elasticity, and cure characteristics.

Properties

Ethylene–butylene elastomers are characterized by low permeability to gases, good heat aging resistance, and favorable ozone and weathering stability. They provide good chemical resistance to certain fuels and oils, while maintaining flexibility over a broad temperature range. The material’s properties can be tailored by adjusting the ethylene/butene ratio and the degree of crosslinking, allowing a spectrum from softer sealants to more resilient elastomers.

Applications

EBR has been used in seals, gaskets, O-rings, hoses, and other automotive and industrial components where low gas permeability and weather resistance are valuable. In many modern applications, it has been largely supplanted by other elastomers such as EPDM and specialized polyolefin elastomers, but it remains of niche use where its particular balance of permeability, chemical resistance, and low-temperature performance is advantageous.

See also

Ethylene-propylene rubber; ethylene copolymers; elastomer.