MICROSTRUCTURE AND TEXTURE OF PITCH-BASED RIBBON FIBERS FOR THERMAL MANAGEMENT

The textures and microstructures of three different experimental mesop hase pitch-based ribbon fibers were studied using the complementary te chniques of scanning and transmission electron microscopy and wide ang le X-ray diffraction. The effect of mesophase pitch precursor and capi llary entry design on the structure and heat transfer capabilities of these ribbon-shaped fibers was investigated. It was found that ribbon fibers melt-spun from a synthetic, naphthalene-based mesophase had hig her degrees of preferred orientation and graphitization, larger crysta llite sizes and lower electrical resistivities than those of fibers me lt-spun from a petroleum-based, heat-soaked mesophase. However, capill ary entry design proved to be critical to the development of a more li near transverse texture and a structure that one might expect to be mo re conducive to axial heat transfer.