Atmosphere influence in the pyrolysis of poly[(alkylamino)borazine] for the production of BN fibers

The effect of pyrolysis atmosphere on products deriving from poly[(alkylamino)borazine] was studied. Pyrolysis in NH3 resulted in BN with almost no carbon content while in Ar led to BNC materials. The crystallinity of the sample obtained in NH3 was higher than that in Ar. BN fibers with almost no carbon impurity were obtained in NH3 and then in Ar, possessing good oxidation resistance and low dielectric constant. The superior properties of BN fibers allow them to be promising in high-temperature, microwave-transparent applications.