High-performance boron nitride fibers obtained from asymmetric alkylaminoborazine

摘要: In order to prepare boron nitride fibers displaying improved mechanical properties, different polymers have been prepared from 2-[(CH3)2N]-4,6-(CH3HN)2B3N3H3 (1) by varying thermolysis conditions. Analytical data showed that the resulting polyborazines 2, 3, 4 and 5 present polymerisation degrees included between 0.7 1.1, confirmed they are composed of borazinic rings connected mainly through direct B–N inter-ring bonds a lesser extent –N(CH3)– bridges. Spinning properties these ceramisation conditions derived crude studied. While spinnability higher cross-linked polymer was poor, all others displayed very good processing as well no reactivity in spinning allowing fabrication high performance fibers. Their tensile strengths over 0.80 GPa often reach 1.10 GPa. The three main characteristics polymeric precursors fibers, namely degree, glass-transition temperature shown be closely related. We observed when displays polycondensation degree is, are. A final pyrolysis 1600 °C is sufficient ensure crystallization BN obtained.