Viscometer shearing disk

In the Mooney shearing disk viscometer, a serrated disk is rotated ia a sample fixed ia a pressuri2ed cavity. The instmment was developed for mbber and other elastomeric materials and is a standard quaUty control iastmment ia the mbber iadustry (ASTM D1646). It is used to measure high viscosities givea ia arbitrary Mooaey units, but usually ca 7.5 x 10 mPa-s atlow(ca 1.5 ) shear rates. 

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]). 

The shearing disk viscometer introduced in 1934 by Mooney [M40] has played a very important role in the rubber industry because of its utilization for monitoring and control of rubber samples (Fig. 14). It is related to the parallel disk type shear flow instrument that has been widely used for polymer solutions and melts. 

FIGURE 14 Shear disk viscometers (a) parallel disk, (b) Mooney. 

In a shearing disk viscometer, the torque M on the disk may be expressed... 

The quality-control shearing disk viscometer has always had only a single rotor speed (2rpm), though Mooney [M42] as early as the 1940s built a multispeed unit. The use of Eq. (81) to determine o (i ) and shear viscosity implies a multispeed instrument. 

Mooney scorch is the time to incipient cure a rubber compound in a test in the Mooney shearing disk viscometer. 

Mooney viscosity measurement of the plasticity or viscosity of an uncompounded or compounded, unvulcanized rubber seal material, by means of the Mooney shearing disk viscometer. 

The earliest and still one of the most popular rheologieal instruments is the shearing disk viscometer. This is generally referred to as the Mooney Viscometer named after Melvin Mooney (1893-1968) of U.S. Rubber. 

Viscometer shearing disk device used to gauge the viscosity of a rubber sample under heat and pressure. Often referred to as the Mooney viscometer, this device was once the most common tool for determining processing characteristics, but has now largely been replaced by the rheometer. 

Many surface viscometers utilize torsional stress measurements upon a rotating ring, disk or knife edge (shown schematically in Fig. 5.16) within or near to the liquid/liquid interface [17]. This type of viscometer is moderately sensitive for a disk viscometer the interfacial shear viscosity can be measured in the range q > 10 Surface Pas. The disk is rotated within the plane of the interface with angular velocity w. A torque is exerted upon the disk of radius R by both the surfactant film with surface viscosity qg and the viscous liquid (with bulk viscosity q) that is given by the expression... 

The disk viscometers are generally less sensitive devices (compared to the channel method) for measuring interfacial shear viscosity (typically -rish — 10 surface poises) and exhibit a more complex flow field. The primary advantage of... 

The knife-edge viscometers are similar to the disk viscometers in most respects. A notable exception is the rotating-wall knife-edge viscometer, which entails the measurement of the velocity of a tracer particle within the fluid interface and is quite sensitive to interfacial shear viscosity measurements, irish 10 surface poises. Presently, this device is the most promising surface viscometer. For more details, see Refs. 58, 153, 154, 158, and 163-170. 

The parallel-disk viscometer used for measuring the shear stress and normal stress difference of molten thermoplastics is similar in principle to the cone-n-plate viscometer except that the lower cone is replaced by a smooth circular disk. This type of viscometer was initially developed for measuring the rheological properties of rubber [29-33] and therefore made use of serrated disks placed in a pressurized cavity to prevent rubber slippage. When it was adapted for thermoplastic melts [1534,35], measurements were performed using smooth disks and without pressure. 

The rheological properties in the parallel-disk viscometer are based on the shear rate at the outer radius of the disk. Thus,... 

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. 

With several springs, which function as torque gauges, and a number of spindles, viscosities can be measured up to 10 mPa-s with the Brookfield viscometer. The shear rates depend on the model and the sensor system they are ca 0.1 100 for the disk spindles, <132 for concentric cylinders, and <1500 for the cone—plate forlow viscosity samples. Viscosities at very low (ca 10 — 1 )) shear rates can be measured with the concentric... 

The Nametre Rotary B rotational viscometer measures torque in terms of the current needed to drive the d-c motor at a given speed while a material is under test. The standard sensors are coaxial cylinders or Brookfield disk-type spindles, but a cone—plate system is also available. The viscosity range for the coaxial cylinder sensors is 5 to 5 x 1(T mPa-s, and the maximum shear rate is 200. ... 

The unsuitable nature of many commercial instruments which are in common use clearly illustrates the confusion prevalent in the field of viscometric measurements. Many instruments measure some combination of properties which depend only partly on the fluid consistency since the flow is not laminar. In others the shear rates are indeterminate and the data cannot be interpreted completely. Examples of such units include rotational viscometers with inserted baffles, as in the modified Stormer instruments in which the fluid flows through an orifice, as in the Saybolt or Engler viscometers instruments in which a ball, disk, or cylinder falls through the fluid, as in the Gardiner mobilometer. Recently even the use of a vibrating reed has been claimed to be useful for measurement of non-Newtonian viscosities (M14, W10), although theoretical studies (R6, W10) show that true physical properties are obviously not obtainable in these instruments for such fluids. These various instru-... 

---