Effect of fiber orientation on spinning dynamics for liquid crystalline polymer solutions using mesoscopic theory

Liquid crystalline polymer (LCP) solutions undergo uniaxial elongation in fiber spinning, yielding highly oriented fibril-structured fibers with enhanced orientation and mechanical properties. This study explores how initial fiber orientation and Frank elasticity influence the dynamics and stability of the isothermal spinning process for LCP solutions. The simplified Larson-Doi mesoscopic model is employed, capable of capturing elastic stress emerging from domain structure evolution. Two main factors, inlet orientation and the Ericksen number as a parameter representing Frank elasticity, significantly affect steady-state fiber orientation profiles and the onset of draw resonance instability, as determined through linear stability analysis. The sensitivity of spinline flow to a sinusoidal disturbance is assessed using the frequency response method. Changes in stability onset concerning these two main factors are reasonably correlated with the extensional behavior of the LCP solution in the spinline and the results of the frequency response.

Graphical Abstract