Nearly stoichiometric BN fiber with low dielectric constant derived from poly[(alkylamino)borazine]

Nearly stoichiometric boron nitride (BN) fiber with low dielectric constant was prepared by curing, pyrolysis of a novel poly[(alkylamino)borazine] (PAAB) under NH3 up to 1200 degrees C in a ceramic yield of 60 wt.%. Based on IR, XRD, XPS and elemental analysis (EA), the fiber with a composition of BN1.09 shows a characteristic of turbostratic BN (t-BN). The tensile strength is approximately 0.6 GPa with 13 mu m in diameter. Moreover, the fiber possesses very low real part (epsilon') of 2.66 and loss tangent (tan delta) of 0.0012 at 10 GHz, respectively, making it possible to be used in microwave-transparent material. (C) 2010 Elsevier B.V. All rights reserved.