Enhancement of fiber structure formation of a liquid crystalline copolyester via ultra‐high speed bicomponent spinning with poly(ethylene terephthalate)

Abstract

AbstractA thermotropic liquid crystalline copolyester, poly(hydroxybenzoic acid‐co‐ethylene terephthalate) (LCP), and poly(ethylene terephthalate) (PET) were coextruded using two different extrusion systems to form sheath‐core type biocomponent fibers. The bicomponent fibers could be spun up to a take‐up velocity of 8 Km/min. The structural characterization of the individual components in the as‐spun fibers showed that the orientation development in the PET component was significantly suppressed compared with the corresponding single component fibers. A significant increase in the tensile modulus of the LCP core component, which was estimated by the simple rule of mixtures, was observed above a take‐up velocity of 4 km/min. The increase in tensile modulus was attributed to the increase in the overall orientation of the LCP core resulting from the combination of the high levels of stress generated during spinning at very high speeds and the altered thermal and stress generated during spinning at very high speeds and the altered thermal and stress histories provided by the bicomponent spinning process. On‐line study of the thinning behavior of single component and bicomponent spinning was carried out in order to gain an understanding of the spinline dynamics, which improved the processability and structure development of LCP.