Viscometers penetration

The layer of soft-ice adjacent to an interface may be melted or disoriented by adding LiCl. By this means Blank 2) has shown that the value of E/ of a monolayer of octadecanol to the passage of CO2 could be reduced from about 300 sec. cm. for pure water to only about 30 sec. cm. for 8M LiCl solution. Under the latter conditions we believe that the soft-ice is apparently almost completely melted. A small amount of methanol in the water penetrates and somewhat disrupts the film of octadecanol, and Ri again drops from 300 sec. cm. to about 30 sec. cm. i, though with further increase in the methanol concentration the resistance increases again to about 500 sec. cm., presumably due to the methanol molecules held in or near the surface increasing the viscosity of the soft-ice layer. These interpretations of the experimental data are not those proposed by Blank, and further studies with a viscous-traction surface-viscometer (1) should certainly be carried out to test this soft-ice theory. 

In addition to the torsion plastograph mentioned above, a number of other methods are used for appraising the properties of plastic bodies in practice. Plastic strength (rigidity) is determined by means of the Rebinder penetrometer which measures the depth of penetration of a cone forced into the body under constant load. The respective quantity is related to yield point. The commercial Brabender plastograph measures the resistance of mixture to kneading. The extrusion viscometer, from which the material is extruded under pressure, is analogous to flow-out viscometers. 

Texture analyzers are also used to assess deformability of a fluid, using penetration force vs. depth profiles, etc. These instruments in addition to Brookfield and Haake viscometers are common QC metrics. Other methods include viscosity flow cups and bubble or falling ball viscometers, and several relevant standard test methods include ASTM D1200, DIN/ISO 2431, ASTM D5125, BS3900 Part A6, ASTM D1545, and ASTM D1725. 

As with other physical properties, viscosity is affected by temperature, with a lower temperature giving a higher viscosity. For most oils, the viscosity varies as the logarithm of the temperature, which is a very significant variation. Oils that flow readily at high temperature can become a slow moving, viscous mass at low temperature. In terms of oil spill cleanup, viscous oils do not spread rapidly, do not penetrate soils rapidly, and affect the ability of pumps and skimmers to handle the oil. The dynamic viscosity of oil (in mPa s) is conveniently measured by a viscometer using a variety of cup-and-spindle sensors at very strictly controlled temperatures. 

A number of other methods are occasionally used for viscosity measurements. The most common are the parallel plate viscometer, used in the 10 -10 Pa s range, the penetration viscometer, used in the 10 -10 Pa s range, and the torsion viscometer, used in the lO -lO " Pas range. Although each of these methods has advantages under specific conditions, none have gained wide acceptance in the glass community. 

Several methods were applied in the studies of rheological properties of paste those based on the acoustic wave velocity, as well as on the measurements of resistance against the force in of penetrator (similar to Vicat apparatus for setting time measurements), also based on the pressure transfer in the paste and different rotation methods with spindle and finally viscometers with co-axial cylinders [5]. 

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