SPINNABILITY OF SILICA SOLS Structural and rheological criteria
نویسنده
چکیده
29Si NMR spectroscopy of concentrated silicate sols, prepared by acid-catalyzed hydrolysis of TEOS in ethanol with H20/Si ratios, r -1.5 or 1.7, followed by alcohol evaporation, shows that the polysilicate species responsible for spinnability are not simple rigid-rod, ladder polymers or linear polymers. Instead a distribution of silicate species is observed consistent with the products of a statistical (random) growth process. The primary criterion for spinnability is high viscosity without premature gelation. This is accomplished under acid-catalyzed conditions with low values of r.
منابع مشابه
Effect of rheology and processing parameters on the EPD coatings of basic sol-gel particulate sol
Homogeneous thick silica coatings were prepared onto metals substrates by Electrophoretic Deposition (EPD) using particulate sol-gel sols. The synthesis of the sols was performed by mixing tetraethoxysilane and methyltriethoxysilane under basic catalysis. The synthesis, storage and processing conditions were optimised, correlating the rheological properties of the sols with EPD performance and ...
متن کاملFrom colloidal-silica sols to aerogels and xerogels
By destabilization of quasi-monodisperse silica sols, fractal clusters can be obtained. Solvent evacuation gives a porous solid with fractal structure. Structural investigations of these colloidal aerogels by small-angle neutron scattering are presented, and compared to similar observations in concentrated sols and xerogels. An investigation of the vibrational modes of these materials by inelas...
متن کاملSilica-Zirconia Coatings Produced by Dipping and EPD from Colloidal Sol–Gel Suspensions
SiO2-ZrO2 sols have been prepared via acid catalysis using a commercial colloidal suspension of zirconia and two silica alkoxides; tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES). Suspensions with 10, 15 and 25-mol% of ZrO2 were prepared. The stability of the suspensions was followed by rheological measurements showing that the amount of water incorporated with the colloidal suspensio...
متن کاملDeveloping a Cost-Effective Approach for Enhancing the Rheological and Mechanical Behavior of High Strength Self-Compacting Concrete
Despite the numerous advantages of using concrete with high strength capacity, the brittle behavior of high strength concrete (HSC) and higher production cost has limited its use in the construction industry. This research aims to develop a cost-effective approach for production of high strength self-compacting concrete with desirable performance in either compressive or tensile loading conditi...
متن کاملPerformance Evaluation of Nano-silica Modified Bitumen
In this study, different contents of Nano-silica, 2 wt.%, 4 wt.% and 6 wt.%, have been added to bitumen to modify the physical, mechanical and rheological properties of warm mix asphalt (WMA). WMA is containing 2 wt.% of Sasobit (mixture of long-chain hydrocarbons). Various quality control tests have been carried out to characterize the modified bitumen and WMA. The rheo...
متن کامل