Synthesis and Characterization of Silicon-containing Polyborazine to Boron Nitride Ceramic Fiber

Silicon-containing polyborazine, a novel precursor to boron nitride ceramic fibers, was synthesized via "one-pot" approach with a yield of about 87% (w%) using boron trichloride (BCl3) and hexamethydisilazane (HMDZ) as the starting materials. The chemical composition, structure and properties of the obtained precursor were investigated using EA, FT-IR, NMR, TMA and dynamic rheological measurement. The results indicate that the backbone of the polymer is N-B linkage in the form of borazine and Si is in the form of Si-CH3 and Si-N in the pendant or end group. The softening point of the precursor is 110 C. The precursor shows good processability and the precursor fibers with diameters of 20 similar to 25 mu m can be obtained by melt spinning at 190 degrees C in N-2 atmosphere.