Homogeneous slurry, rheology

For the production of preceramic slurries, fillers in the submicron range have to be used to achieve homogeneous infiltration of a fiber bundle with several thousands of filaments. This requires detailed knowledge of the rheological behavior of the powder-filled dissolved polymers. Additives are necessary to achieve high filler contents and good rheological behavior. 

The compound or heterogeneous-homogeneous system is the most important and most common in slurry transportation. It involves coarse and fine particles. The fines move as a homogeneous mixture while the remainder move as a heterogeneous mixture. To conduct this analysis, the rheological and physical properties of the solids must be known. 

Calculate the friction losses of the homogeneous fraction based on the rheology of the slurry, assuming Newtonian flow. 

Cellulose pretreated in the presense of TMAC failed to exhibit enhanced activity toward sodium trichloroacetate in an isopropanol slurry. Products with essentially identical D.S. s were isolated from "catalysed and control experiments. However, solutions of catalysed CMC, (D.S.=0.7), appeared more fiber free than those prepared from controls with similar D.S.. The catalysed solutions (1%) exhibited slightly higher viscosities (500 cp vs 325 cp) and were less thixotropic than standard CMC. Efforts to ascertain if this difference in rheological behavior can be attributed to a more homogeneous distribution of substituents are in progress. 

---