Orientability of liquid crystal polymers in elongational flow

The orientation development in elongational flow (spinning) of liquid crystal polymers (LCP) has been studied and a physical model derived which relates the modulus development and extensional deformation. The model defines an orientability parameter, λ, which in addition to the total elongational deformation (drawdown ratio) are related to the orientation (modulus) level of the final spun fiber. Five LCPs were included in the study—a lyotropic polymer: Poly (p‐phenylene‐terephthalamide) and four wholly aromatic naphthalene‐containing polyesters. The experimental results have shown good agreement with the proposed model and indicate that λ is independent of the spinneret size and is characteristic of the orientability in elongational flow of each of the polymers investigated.