Boron-containing poly(vinyl alcohol) as a ceramic precursor

In this paper, a preceramic precursor, prepared by condensation reaction from poly(vinyl alcohol) (PVA) and boric acid (B(OH)₃) in a B–OH: PVA-OH molar ratio of 1:1, was synthesized, as a potential precursor of lower-temperature route for ceramic material. The polymer-to-ceramic conversion was studied by thermogravimetry (TG), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The kinetics parameters, such as the activation energy (AE) involved in the polymer-to-ceramic conversion, were investigated by dynamic thermogravimetric analysis. The AE value for each step was correlated to the molecular architecture and degree of crosslinking of the precursor. The FTIR spectrum of the precursor showed B–O, C–H and B–O–C stretching modes. The polymer underwent a thermal degradation in three-steps, yielding 17.1 wt% of ceramic char at 980 °C. The XRD study showed the formation of B₂O₃ crystalline phase dispersed in the graphitic carbon phase, as the final product.