What is "elastolefin"

n. Any of a range of cross-linked polymers (of ethylene and other olefins) whose fibres have good elastic properties

Elastolefin is a fibre composed of at least 95% (by weight) of macromolecules partially cross-linked, made of ethylene and at least one other olefin. When stretched to one and a half times its original length, it recovers rapidly to its original length. It therefore will stretch up to 50% and recover. Recent updates to EU fabric labelling directive to include elastolefin in Anex I and II.