Spinnability of silica sols structural and rheological criteria

摘要: Abstract 29Si NMR spectroscopy of concentrated silicate sols, prepared by acid-catalyzed hydrolysis TEOX in ethanol with H2O/Si ratios, r ≈ 1.5 or 1.7, followed alcohol evaporation, shows that the polysilicate species responsible for spinnability are not simple rigid-rod, ladder polymers linear polymers. Instead a distribution is observed consistent products statistical (random) growth process. The primary criterion high viscosity without premature gelation. This accomplished under conditions low values r.