A chain extender is a short chain diol used in polyurethanes and polyurethane-based thermoplastics (TPU) to create hard blocks.
TPU’s special properties are highly linked to the presence of such blocks, and POLYSORB® isosorbide can be used as a chain extender in replacement of the commonly used 1,4-butanediol.
Other questions - About Isosorbide
Is POLYSORB® isosorbide also a linear chain extender?