Rheological testing systems viscometers

Clearly, the response of fluids to an applied shear can be linear or nonlinear and depends on two major factors shear rate and structural or mechanical properties of the system, which in turn depend upon the interaction between the components including the rheological additives. It is the latter that primarily determines the flow properties of LADDs. The intent of this section is to discuss various rheological properties and test methods pertinent to LADDs. Interested readers are referred to Chapter 4, which deals with the rheology of complex liquids and suspensions, and other books [76-79] and review articles [80-82] covering this subject. Heywood [83] discusses the criteria for selecting various commercial viscometers. 

Several researchers reported viscoelastic behavior of yeast suspensions. Labuza et al. [9] reported shear-thinning behavior of baker s yeast (S. cerevisiae) in the range of 1 to 100 reciprocal seconds at yeast concentrations above 10.5% (w/w). The power law model was successfully applied. More recently, Mancini and Moresi [10] also measured the rheological properties of baker s yeast using different rheometers in the concentration range of 25 to 200 g dm. While the Haake rotational viscometer confirmed Labuza s results on the pseudoplastic character of yeast suspension, the dynamic stress rheometer revealed definitive Newtonian behavior. This discrepancy was attributed to the lower sensitivity of Haake viscometer in the range of viscosity tested (1.5 to 12 mPa s). Speers et al. [11] used a controlled shear-rate rheometer with a cone-and-plate system to measure viscosity of... 

The rheological measurements were carried out using the rate controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-Osc., measuring device MVIP with serrated surfaces. The temperature was kept strictly constant at 25 0.1°C. The tests were accomplished under both continuous and oscillatory flow conditions. Flow curves were... 

A range of thiuram secondary accelerators is evaluated in an ENB-based EPDM compound and in a new technology EPDM compound. The recipes used are fairly basic, utilising CV and EV vulcanisation systems. The rheology is tested on an MDR rheometer and the compound viscosity and scorch tested on a Mooney viscometer. Stress-strain properties are established after cure at 160 deg.C and after ageing at 100 deg.C. In addition, tear properties and compression set values at various temperatures are determined. The observed... 

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