Induced by different fillers, various hydrodynamic effects enhance the fibrillation of liquid crystalline polymer (LCP) in in situ hybrid composites. Through choosing CaCO3 whisker as the filler and polysulfone (PSF) as the matrix, the effect of the filler size and the affinity between components on the morphological evolution of LCP droplets has been investigated. In contrast to the spherical or ellipsoidal droplets of LCP formed in binary PSF/LCP blends, the fibrillation of LCP was promoted by the introduction of whisker particles in all ternary blends at shear rates studied. The analysis of the flow field indicated that the predominant factors promoting the fibrillation of LCP were the vortex enhanced and elongational stress increased by the whisker in the converging flow area at the entrance of capillary, rather than the viscosity ratio and capillary number. (c) 2006 Elsevier Ltd. All rights reserved.