Synthesis and characterization of polyvinyl butyral–Al(NO3)3 composite sol used for alumina based fibers

The polyvinyl butyral–Al(NO3)3 composite sol used for alumina based fibers was synthesized by the sol–gel process in an aqueous solution using the polyvinyl butyral (PVB) and Al(NO3)3 · 9H2O (AN). The alumina fibers with smooth surface and uniform diameter were prepared. PVB, AN, PVB–AN composite sol and alumina fibers have been studied by X-ray diffraction (XRD), derivative thermo-gravimetric/differential scanning calorimetry (DTG/DSC), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The interaction between PVB and AN was reported. The presence of a new weak peak at low angle and deviation of diffraction angle in XRD patterns implied that the reaction between PVB and AN took place. DTG/DSC curves showed the decomposition temperatures of AN increased and that of PVB decreased in the PVB–AN composite sol, which was considered to be caused by the interaction between PVB and AN. FTIR spectroscopy of PVB–AN gel showed a new absorption peak due to the COOH group, which implied the presence of new reaction product. The schematic reaction formula was shown in this paper. The XRD pattern of fibers sintered at 1,200 °C showed the formation of α-alumina and the fibers showed smooth surface and uniform diameter.