Stability of blends of polyethersulfone with thermotropic liquid crystalline polymers

The formation and stability of various liquid crystalline polymers in an amorphous polymer matrix, Polyether sulfone (PES) over the melting temperature has been studied by in-line optical video microscopy and light scattering. The fiber breakup morphology profiles after shear cessation was examined to study the stability of the thermotropic liquid crystalline polymers (TLCP) fibers in the PES matrix. The TLCP are aromatic copolyesters with different chain structures, Ln 001 and LC-5000. Shear induces a droplet-fiber transition along the flow direction, but the TLCP fibers are highly unstable and can break up in a few seconds upon cessation of shear. The TLCP fibers break up into droplets by the combination of Rayleigh distortions, end pinching and retraction. The apparent values for the interfacial tension was calculated with Tomotika's theory and compared with the individual fiber experiment in literatures. The results suggest that the viscosity ratio and the interfacial tension between the materials components control both the shear-induced fiber formation and fiber stability.