From the summary: We extend a model of liquid crystalline to include a fully three-way coupling of flow, orientation and crystallization mechanics, adopting the Avrami crystallization law with an orientation-dependent rate constant and the Kikutani stress-hardening law. We show that there is a significant difference in the fiber diameter profile, orientation and crystallinity with the inclusion of stress-hardening in the extensional flow. Of interest here is also the role of crystallization in localizing the drawdown into a so-called ‘neck’ region. We illustrate important qualitative and quantitative effects due to the development of crystallization on the examples of a pronounced drop in the fiber radius, an increased rapid fluid acceleration, and enhanced molecular alignment with the fiber centerline axis.