Plastometers

Plasticity can be studied using a device known as the Gieseler plastometer. A constant torque is appHed to a shaft with rabble arms imbedded in coal in a cmcible heated at a fixed rate. The rate of rotation of the shaft indicates the duidity of the coal and is plotted as a function of the coal temperature. These curves, as shown in Figure 8, have a well-defined peak for coking coals usually near 450°C. Softening occurs at 350—400°C. At a normal heating rate of 3°C/min, the duid hardening may be complete by 500°C. 

Fig. 8. Plasticity curve obtained using the Gieseler plastometer. Heating rate is 2°C/min.

Flowability MFI melt flow index, ASTM D 1238 Procedure A Extrusion plastometer... 

Figure 10.1 Parallel-plate plastometer for determination of consistency.

The consistency depends on the powder/liquid ratio used to mix the cement, and the parallel plate plastometer can be used to determine the optimum ratio for a particular cement system. 

Figure 5.5 shows a schematic diagram of a melt indexer (which is also sometimes referred to as an extrusion plastometer). To determine the melt flow rate of a polymer resin, we place a suitable mass of it into the barrel, which is pre-heated to a standard temperature appropriate to the polymer. We then place a weighted piston on top of the sample. After allowing the polymer to reach the temperature of the barrel we allow it to extrude from the capillary orifice. The melt flow rate is the mass of polymer in grams that extrudes in ten minutes. 

ASTM D1238-04c Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer, Book of Standards Vol. 08.011, ASTM International (formerly known as American Society for Testing and Materials), West Conshohocken, PA, USA. 

A type of parallel plate plastometer developed in Germany it differs from the conventional parallel plate instrument in that it measures the load required to deform the test sample by a specified amount in a fixed time. 

Since all practical methods of measuring the hardness of mbber involve measuring the resistance to indentation, hardness may be defined simply as resistance to indentation . Hardness is an expression of the elastic modulus of the mbber. More specifically, the load required to press a ball of given diameter to a given depth into the mbber is proportional to its elastic modulus. See Hardness Testing, Pusey and Jones Plastometer, Microhardness Testing. 

Any instrument for measuring the plasticity of an elastomer. See Mooney Viscometer and Williams Plastometer. 

This is an instrument for hardness testing and not a plastometer. The Pusey and Jones tester is used for determining hardness particularly on curved surfaces, such as rubber-covered rolls. It operates on a dead-weight principle. 

The earliest and best-known of parallel plate plastometers. The original model has been... 

ASTM D1238-04c, Standard Test Method for Flow Rates of Thermoplastics by Extrusion Plastometer, (2004)... 

Plastometers—Manufacture, Properties and Application," vol 2, Elsevier Amsterdam (1949), Chap 13, "Asphalt, by R.N.Traxler... 

Giesler plastometer tests were conducted on the vitrinoids of Seams 2 and 4, respectively. They did not show any fluidity characteristics at all, and the... 

Constant torque plastometer ddm- —dial division per minute. ... 

Constant torque plastometer ddm—dial division per minute. 

In 83) the authors studied the flow of polypropylene and polyethylene with the help of a constant-velocity viscosimeter developed on the basis of a standard extrusion plastometer for measurement of the melt flow index (MFI) to the stem of which acoustic vibration was applied. 

Testing with a Gieseler plastometer (ASTM D-2639) gives a semiquantitative measurement of the plastic property, or apparent melting of coal when heated under prescribed conditions in the absence of air. The chemical nature of the constituents that account for a coal s plastic properties is not known. The material thought to be responsible for the plastic properties of coal has been removed from coal successfully by solvent extraction, leaving a nonplastic residue. Such residue has been rendered plastic by returning to it the extracts obtained by the solvent extraction. No definite relationship has been established between the amount of extract and the plastic properties of the coal. 

In the procedure (ASTM D-2639), the sample is air dried prior to preparation and the temperature should not exceed 15°C (59°F) above room temperature, and drying should not be continued to the extent that oxidation of the coal occurs and the plastic properties of the coal are not altered by oxidation. The apparatus is then immersed in the heating bath and a known torque applied to the stirrer. During the initial heating no movement of the stirrer occurs, but as the temperature is raised, the stirrer begins to rotate. With increasing temperature, the stirrer speed increases until at some point the coal resolidifies and the stirrer is halted (Figure 7.4). The plastic properties of the sample are then measured by the resistance to motion of the fluid mass in the plastometer. 

The values normally determined with the Gieseler plastometer are ... 

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