Viscometer Mooney

Monuron Monzomte Moody diagram Mooney viscometer Mooney viscometers MOPAC 5.0 benchmark 4-79Mo-Permalloy Mopping asphalt Morantel [20574-50-9]... 

OtherRota.tiona.1 Viscometers. Some rotational viscometers employ a disk as the inner member or bob, eg, the Brookfield and Mooney viscometers others use paddles (a geometry of the Stormer). These nonstandard geometries are difficult to analy2e, particularly for an infinite bath, as is usually employed with the Brookfield and the Stormer. The Brookfield disk has been analy2ed for Newtonian and non-Newtonian fluids and shear rate corrections have been developed (22). Other nonstandard geometries are best handled by determining iastmment constants by caUbration with standard fluids. 

Development of the Mooney viscometer gave compounders an indication of the processibiUty of different lots of the uncompounded polymer. This machine measures the torque resistance encountered by a rotor revolving in a chamber surrounded by polymer at a constant temperature. The resulting Mooney number describes the toughness of the polymer and is an indirect measure of molecular weight. 

Mooney Viscometer studies at 100°C and 120°C show lower viscosity of the Al-hlled gums. Lower viscosity compounds require less energy input for extrusion. Comparative results on the dynamic mechanical properties, measured using a rubber process analyzer (RPA), show that at the... 

The B-series of silica samples were also blended with rubber and the compound formulation is shown in Table 17.6. The uncured gums were then tested according to ISO 5794-2 1998. The uncured samples were tested using a Mooney viscometer and an RPA, which measures the dynamic mechanical properties as the samples cure. Figure 17.7 shows the results of these two tests for the Mooney viscosity at 100°C, storage modulus, loss modulus, and tan 8. 

Melvin Mooney devised an instrument to measure the stiffness of uncured compounds, also known as the compound s viscosity. The unit of measurement is expressed in Mooney units. Figure 28.1 shows an instrument set up for measuring viscosity, the Mooney viscometer, in which a knurled knob (rotor) rotates (at 2 revolutions per minute) in a closed heated cavity filled with rubber [2]. 

Mooney viscometer is also used to measure the time it takes, from initial exposure of the compound to a particular temperature, to the time of onset of cure at that temperature [2]. This is known as the scorch time. Scorch time is an important parameter to the rubber processor, as a short time may lead to problems of premature vulcanization. As the test is taken past the onset of cure, the rotor tears the cured rubber, and therefore this device cannot be used to investigate rheological properties after the scorch time. 

S. Montes, J.L. White, N. Nakajima, F.C. Weissert, and K. Min, An experimental study of flow and stress fields in a pressurized Mooney viscometer. Rubber Chem. TechnoL, 61, 698-716, 1988. 

The name Mooney is often used in referring to the value obtained on the Mooney viscometer. Mooney Scorch Test... 

A development of plasticity determination by means of the Mooney viscometer. The same instrument is used but the temperature of operation is higher and the test is continued until the sample vulcanises. A curve of Mooney reading against time is drawn, from which the scorch and cure characteristics are estimated (BS 903-A58). 

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

An instrument for the study of the rheological properties of a substance. The name has been applied to several modified versions of the Mooney Viscometer and to the Monsanto (now... 

In general a rotating part of a machine in the mbber industry the term refers particularly to the contoured rolls of an internal mixer and to the mushroom-shaped rotor of the Mooney Viscometer. 

An apparatus for measuring the viscosity of unvulcanised elastomers. The best known is the Mooney viscometer. 

An early cure instrument which combined in one operation the functions of a Mooney viscometer and of a curometer or vulcameter, i.e., it measures in one quick test the plasticity (viscosity) of the (uncured) mix, its scorch time and cure rate. Now superseded by instruments such as the moving die rheometer. 

A number of techniques have been developed to measure melt viscosity. Some of these are listed in Table 3.8. Rotational viscometers are of varied structures. The Couette cup-and-bob viscometer consists of a stationary inner cylinder, bob, and an outer cylinder, cup, which is rotated. Shear stress is measured in terms of the required torque needed to achieve a fixed rotation rate for a specific radius differential between the radius of the bob and the cup. The Brookfield viscometer is a bob-and-cup viscometer. The Mooney viscometer, often used in the rubber industry, measures the torque needed to revolve a rotor at a specified rate. In the cone-and-plate assemblies the melt is sheared between a flat plate and a broad cone whose apex contacts the plate containing the melt. 

The scorch behaviour of compounds is generally studied with the help of a mooney viscometer. The test is usually conducted at temperatures encountered during processing of the rubber stock. Typically this is in the temperature range of 250°F to 275°F. From a chart of mooney units vs test time, the time required for the... 

The most common method of measurement is to run the compound in the mooney viscometer until the viscosity shows a 5 point rise above the minimum. The viscosity of the compounded rubber at the processing temperatures can also be obtained from the minimum of the curve. The values normally taken from the cure curve are ... 

In all the above methods, it is necessary to cure specimens of test samples for each of a series of curing times and then perform the desired test on the vulcanizate. However, in the test for continuous measurement of vulcanization complete information could be obtained with saving in time. The mooney viscometer test approaches this objective. However a weakness of the mooney viscometer test is that the test is completed before a measurable modulus value after the scorch point has been obtained. This is because the test sample is destroyed after the induction period is passed due to tearing by continuous rotation of the rotor whether small or large. To overcome this deficiency and to provide a total cure curve for the entire vulcanization cycle, a series of instruments called cure meters was developed. In each of these instruments the stiffness or modulus of the compound was chosen as parameters for vulcanization continuously. The Vulkameter developed by Bayers, Germany was the first of the cure meters developed. 

A number of plastimeters of this type have been used for rubbers, often for research purposes, but one instrument, the Mooney viscometer, gained virtually universal acceptance and has been extensively used for routine quality control purposes for several decades. The principle of the Mooney is shown in Figure 6.4 together with several other possible geometries for a rotational instrument. The rotor turns at a constant rate inside a closed cavity containing the test piece so that a shearing action takes place between the flat surfaces of the rotor and the walls of the chamber. The torque required to rotate the rotor is monitored by a suitable transducer. 

If a fully compounded thermosetting rubber is subjected to a plasticity measurement at a high enough temperature and for long enough, it will cure and, consequently, there is not always a clear distinction between a plasticity test and a test for scorch or rate of cure. For example, the Mooney viscometer is used to measure scorch, i.e. the onset of vulcanisation, and an oscillating disc rheometer will measure the plasticity of the compound before the onset of cure as well as the increase in stiffness as curing takes place. 

The Mooney viscometer offers a more convenient way of measuring scorch and even rate of cure, and a standard method for scorch is given in ISO 289-238 and the BS and ASTM equivalents39 40, as mentioned in Section 3.3 of this chapter. This is essentially the method of ISO 289-1 continued until the viscosity reaches a specified number of Mooney units above its minimum value, either 5 or 3 units depending on whether the large or small rotor is used. The minimum viscosity and the time to reach 5 or 3 units above minimum viscosity are reported. In earlier versions of this test the difference between times to 5 units and 35 units above minimum viscosity was taken as an indication of the rate of cure, but this measure of cure rate is now been superceded. 

ASTM D1646, 2004. Viscosity, stress relaxation and pre-vulcanisation characteristics (Mooney viscometer). 

ASTM D3346, 2003. Processibility of emulsion SBR (styrene-butadiene Rubber) with the Mooney viscometer (Delta Mooney). 

Mooney viscosity—measure of the resistance of raw or unvulcanized rubber to deformation, as measured in a Mooney viscometer. A steel disc is embedded in a heated rubber specimen and slowly rotated. The resistance to the shearing action of the disc is measured and expressed as a Mooney viscosity value. Viscosity increases with continued rotation, and the time required to produce a specified rise in Mooney viscosity is known as the Mooney scorch value, which is an indication of the tendency of a rubber mixture to cure, or vulcanize, prematurely during processing. 

Mooney viscosity is used to measure the extent of mastication. Mooney viscosity is the torque required to rotate the disk in the shearing disk viscometer. When the disk or rotor as it is called, is rotating without any load, the Mooney viscosity reading is zero . When a torque of 100 Nm is applied on the rotor the viscosity scale is read as 100. This is the scale in the Mooney viscometer (ASTM D1646 [2]). 

ASTM D1646, Standard Test Methods for Rubber — Viscosity, Stress Relaxation and Pre-vulcanisation Characteristics (Mooney Viscometer), 2007. 

Whatever the reason, it will be assumed that the cure reaction obeys a first-order reaction, as said by various authors. And, thus, a reference temperature with reference time will not be necessary or even useful. However, it is useful to know the time at which the cure reaction starts for a rubber sheet. The Mooney viscometer is pretty well described in Reference [3]. 

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