Correlation between Molecular Stacking and Anisotropic Texture in Spinnable Mesophase Pitch

Abstract

The correlation of the anisotropic texture and (002) molecular stacking property of spinnable mesophase pitch was closely examined. Spinnable mesophase pitch was found to be a specific solution which consisted of mesogenic and solvent components. Here, the mesogenic component composed of the cluster unit of the (002) stacked molecular sheets. In addition, the anisotropic texture of spinnable mesophase pitch showed a strong correlation with the height of (002) molecular stacking. When the concentration of mesogenic component to the solvent one is higher than the threshold concentration, spinnable mesophase pitch always showed 100 vol% anisotropic texture and the similar or larger number of stacked (002) sheets than that of its mesogenic component in both the solid and melt states. The solvent component in the lamellar and hexagonal phases may help the orientation of mesogenic molecules and rearrangement of mesogenic cluster units, inducing a higher graphitization degree than that of the mesophase pitch with solvent-free. The schematic phase model of spinnable mesophase pitch was proposed by the authors based on a lyotropic liquid crystalline system and the hierarchical domain model.