Combustion behavior and thermal stability of TPU composites based on layered yttrium hydroxides and graphene oxide.

Layered yttrium hydroxides (LYH)- and graphene oxide (GO)-supported layered yttrium hydroxides (GO–LYH) were synthesized by a co-precipitation route. The additives were characterized by X-ray diffraction and Fourier transform infrared spectra. The LYH were homogeneously dispersed on the GO sheets, demonstrated by the transmission electron microscope analysis. Composites of TPU/LYH and TPU/GO–LYH were prepared by a melt-blending method. The morphologies and structures of the composites, revealed by scanning electron microscope, ascertained that the dispersion of the GO–LYH in the TPU was better because of the strong interaction of the hydrogen bonds between oxygen-containing groups and hydroxyl groups. The fire retardancy of the TPU composites was evaluated using limiting oxygen index (LOI), cone calorimetry and thermogravimetric analysis. The TPU/LYH and TPU/GO–LYH composites, filled with 10 mass% LYH, 9 mass% GO, achieved LOI values of 24.4% and 25.3%, while there was a 67.42% and 70.88% decline of PHRR compared with pure TPU. The improved flame retardancy and smoke suppression were attributed to the physical barrier of GO and the catalytic carbonization of LYH indicated by char analysis. [ABSTRACT FROM AUTHOR]