Melt-spinning of non-circular fibers from mesophase pitches

Hollow, ribbon, Yshaped and circular pitch fibers were spun from thermally and catalytically condensed mesophase pitches by using five selfdesigned spinnerets. It was proven in the experiment that the dieswell of molten pitch is an important rheological parameter affecting the formation of noncircular, especially hollow fibers. This parameter changes along with the properties and the melt temperature of mesophase pitch. At relatively higher temperature, the dieswell of molten pitch became smaller, and then the noncircular degree of crosssection of the spun fibers decreased. It was known from Xray diffraction analysis that the different shaped spinnerets, with different hydraulic diameters, exerted different shear actions on the pitch melt during the spinning. The smaller the hydraulic diameter, the stronger the shear action exerted, resulting in the increase of the orientation of the pitch molecules along the axis direction and then the mechanical properties of the carbon fibers obtained.