Polyaceticzirconium for zirconia continuous fibers: Polymeric evolution process and the relationship between polymeric structure and rheological behavior

摘要

Polyaceticzirconium (PEZ) sol, which is the precursor of zirconia (ZrO2) continuous fibers, has been synthesized by means of the reaction between zirconium oxychloride octahydrate (ZrOC2 center dot 8H(2)O) and potassium acetate (CH3COOK) in methanol. The polymeric structures and the rheological behaviors of the sols with different molar ratios of ZrOCl2 center dot 8H(2)O/CH3COOK are different and would affect the spinnability and stability significantly. Herein, the polymeric structures and rheological behaviors of the PEZ sols with the molar ratios of 1:1, 1:1.5, 1:1.8 and 1:2 were investigated by Fourier transform infrared (FT-IR), H-1 nuclear magnetic resonance spectrum (H-1-NMR), thermogravimetry and differential thermal analysis (TG/DTA) and rheological measurements. The results showed the carboxyl group acted as a chelating ligand instead of bidentate ligand, and the water molecule coordinated to Zr4+ was deprotoned gradually with the decrease of the molecular ratios. The different polymeric structures lead to a different theological behaviors of the sols. It is divided into three types, the Newton fluid with a low viscosity produced by the charged linear polymeric structures, the shear thinning fluid with a high viscosity produced by the three-dimensional polymeric structures and the shear thinning fluids with a proper viscosity produced by the linear twining polymeric structures. Through the experimental guidance, we successfully synthesized a sol with suitable viscosity and stability, and used it to fabricate high quality ZrO2 fibers.