Colloid rheology

Industrial process streams are frequently treated as being single phase fluids having simple properties of viscosity and density for calculations involving 

1) Pigments are insoluble, finely divided materials that are dispersed in a formulated s) tem in order to colour it or make it opaque, for example, I1O2 in soap bars and paints, iron oxides in eye make-up and paints. 

Emulsions, Foams, Suspensions, and Aerosols Microscience and Applications, 

Example 6.1 Consider the observed properties of bituminous froth produced in the oil sands hot water flotation process. When fresh, the froth is very viscous when stagnant (hard to pump) but becomes less viscous (twice as easy to pump) when it is flowing. As it is handled, or stored, the entrained air is released and it becomes less viscous (eventually six times as easy to pump). Its viscosity, whether fresh or aged, is exponentially related to temperature so that upon cooling from process temperature to ambient temperature, it becomes 50-200 times more dif-flcult to pump. 

You have a pump that was designed to handle fresh, flowing froth at a process temperature of 80 ° C, but there is a process interruption and the pump is halted for 2 days, during which time the whole circuit cools to the treatment plant s ambient temperature of about 20 °C. What will happen when you eventually try to restart the pump  

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Dickinson, E. (1997b). Enzymic crosslinking as a tool for food colloid rheology control and interfacial stabilization. Trends in Food Science and Technology, 8, 334-339. 

Krieger IM (1963) A dimensional approach to colloid rheology. Trans Soc Rheol 7 101-109... 

Fig. 1 A schematic comparison between polymer melt rheology and colloid rheology, (a) In a polymer melt, atypical chain (dashed curve) is constrained by many (in reality, 10 ) other chains, here represented by small circles. This gives rise to the fruitful mean-field concept of a tube in which the chain has to move, (b) In a concentrated colloidal suspension, a typical particle (hatched) is surrounded (in 3D) by 10 neighbours. This number is too small for mean-field averaging to be meaningful, (c) Large deformations in polymer melts, such as the process (i) -(ii), involves breaking covalent bonds, and so do not ordinarily occur, (d) There are no covalent constraints on order unity deformations, such as (i)—>(ii), in a colloidal suspension...

Optical and spectroscopic properties of model colloids, rheological properties, electrophoretic properties... 

Handling properties of colloids, rheology, sintering Destruction of unwanted colloidal phenomena... 

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