THE CHANGE OF FLOW CHARACTERISTICS OF SI(OC2H5)4 SOLUTIONS IN THE COURSE OF SOL-TO-GEL CONVERSION

Flow characteristics of tetraethoxysilane (TEOS) solutions of the composition TEOS:H//2O:C//2H//5OH:HCl equals 1:2:1:0. 01 in mol was investigated by measuring the viscosity at various shear rates. The nature of the sols prepared in the open and in the closed system has been compared. The open system solution behaves as a Newtonian liquid up to a viscosity of log eta equals 2. 3 P and exhibits spinnability in the viscosity range log eta equals 1-2 P. On the other hand, the closed system solution behaves as non-Newtonian liquid in the viscosity range log eta APP GRTH 1 P and shows negligible spinnability. Formation of some network structure is proposed in the closed system solution but not in the open system solution.