Viscosity titania

Adsorption isotherms for AMP-QS onto kaolin, titania and calcium carbonate are shown in Figure 4. Viscosity profiles obtained when AMP is used to disperse titania and kaolin are shown in Figures 5-7. 

Figure 5 Viscosity versus dose for titania dispersed with AMP...

Figure 10.6. Surfactant demand curves of 70% (weight) dispersions of Ti02 pigments with various levels of alumina treatment. Dispersions were prepared in DIDP plasticizer on a highspeed disk mill. Survactant used was Disperbyk I. Pigment A titania surface, no alumia surface treatment. Pigment B 1.5% alumina surface treatment, minimum viscosity achieved at 2.36% surfactant based on pigment weight. Pigment C 3.0% alumina surface treatment, minimum viscosity at 3.9% surfactant.

Because of this relationship, it does not always follow that catalysts with higher titania contents must deliver the highest MI potential (see footnote 16 on page 294). There is an interaction with activation temperature as well. For example, Figure 107 is a plot of the fluidity of polymers obtained from cogelled silica-titania catalysts [548], Like MI, fluidity is an indication of how easily the molten polymer flows at low shear rates. Whereas MI measures the flow (shear) rate under constant shear stress, fluidity measures the shear stress at constant shear rate (0.1 s-1). Fluidity is the inverse of melt viscosity, and like MI, it varies inversely with MW. 

FIGURE 107 Fluidity (inverse of melt viscosity) of polymers made with cogelled Cr/silica-titania catalysts of varying titania contents. In this plot, the fluidity (similar to melt index) is increased (lower MW) by titania, but titania also promotes sintering at high temperatures. (Ti02 listed in mol%.)... 

FIGURE 111 Arnett plot representing polymers made with titanated Cr/silica activated at 550 °C, showing the influence of titania on the melt viscosity (Tested at 85 °C with 0.50 mol 1-hexene L ). 

FIGURE 117 Properties of polymers made with silica-titania that was calcined at 820 °C, then impregnated with an anhydrous solution of chromium, followed by a secondary calcination step in air as shown. Melt viscosity was measured at 190 °C and 0.1 s ... 

FIGURE 124 Properties of polymers made with R R-activated catalysts. Cr/silica-titania was calcined 3 h at 871 °C in N2, CO, or CS2, then in air 2 h at the indicated temperature. The MW and the fluidity (similar to melt index) of the resultant polymers are plotted. Fluidity is the inverse of the melt viscosity, measured at 0.1 s 1. 

Finally, the rheological behavior of the pure and the filled polymer at different temperatures are presented in Figure 6. As expected the complex viscosity of the melt is increased by the addition of the titania particles. The coated powders showed a smaller increment in the viscosity, which can be translated to better processability. 

Flame reactors are used to produce inorganic oxide particles by burning some kind of starting material. This method has been used to produce pyrogenic silica (used in natural and synthetic rubber, and as a viscosity modifier in paints and inks), pigments such as titania, and other powdered materials such as alumina,... 

Ceramic foams are produced from organic precursor foams such as polyurethane or polyolefins. Their pores are then filled with an aqueous slurry of the ceramic typically containing 20 wt.% of ceramic particles in the size range of from 0.1 to 10 pm [461]. Wetting agents, dispersion stabilisers and viscosity modifiers are added to the slurry. Suitable ceramics are alumina, alumina silicates, zirconia, stabilised zirconia and titania, amongst others. The pores ofthe precursor foam may be filled completely or only coated on their surface by the ceramic particles. The foam is then dried and calcined at 1000 °C, which removes the polymer and sinters the ceramic. Metallic foams have similar properties compared with ceramic foams, but superior mechanical stability and improved heat conductivity. 

Effect of solution viscosity on nanofiber morphology studied in polymer/titania systems. 

Ru(bpy) " in Silica-Titania. Tris(2,2 -bipyridine)ruthenium(II), Ru(bpy)3 ,has received the considerable attention because of its unique properties such as strong luminescence, moderate excited-state lifetime, energy and electron transfer reactions and chemical stability (Kalyanasundaram, 1992). The luminescent excited state of Ru(bpy)3 isassigned to the metal-to-ligand charge-transfer (MLCT) state. The luminescence properties are very sensitive to polarity and viscosity of solvent because of the MLCT character. When Ru(bpy)3" is excited, solvent reorientation aroimd the excited state molecules occurs to stabilize the MLCT excited state with a large dipole moment. Therefore, a blue shift of the luminescence is induced when motion of the solvent molecules is restricted. 

Lin used QELSS to study diffusion of 155 and 170 nm nominal radius titania spheres in a melt of 7500 Da polyethylene oxide(ll). Over a 75 °C temperature range, Dp changes by nearly two orders of magnitude. Comparison was made with the viscosity obtained using a cone-and-plate viscometer. The observed microviscosities were substantially less than the measured viscosity. An extrapolation procedure based on the apparent activation energy, as inferred from the temperature dependence of rj, was used to estimate an effective shear rate for probe diffusion > 10 s , corresponding via y D/L to probe diffusion over atomic distances. Such distances would rationally be fundamental if the unit step for probe diffusion in a polymer melt were the displacement of a single layer of polymer chains. 

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