Mooney viscosity values

Moonej Viscosity. This is a measurement of the viscosity of the polymer that is commonly used ia the mbber iadustry. Mooney viscosity values typically range from 25 to 100. Mooney viscosity generally relates to polymer molecular weight, with the lower Mooney viscosity polymers providing improved flow and processiag characteristics and the higher Mooney NBRs providing improved physical properties. 

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. 

Figure 31 Comparison of two SBR 1006 polymers from different producers with the same tested Mooney viscosity values. Graph shows tan5 response in an RPA frequency sweep at 100 C. 0.5 degrees arc.

Incorporation of carbon black (CB) increased the viscosity of the mixture while the smaller the CB particles the higher the Mooney viscosity value measured. This is related to the enhanced bound rubber content which followed the increase of the surface area of CB as the particle size was decreasing for the same filler content. 

In a silica-filled NR/CR mix, Sae-oui et al. studied the Mooney viscosity (MLl-l-4 at 100 °C) for various NR/CR weight ratios. As shown in Figure 9.1(a), CR presented the lowest viscosity value (i.e. 44) while by blending it with NR (having a Mooney viscosity value of 74), the batch became more viscous. The Mooney viscosity increment was almost linear up to a CR/ NR weight ratio of 25/75, whereas it was saturated for more NR-rich compounds. 

The Mooney viscosity value of the maleated natural rubbers/poly(methyl methacrylate) blends increased with an increased concentration of maleic anhydride used in the grafting copolymerization. The shear flow property of the... 

Figures 1 and 2 show the Mooney viscosity values obtained from a single Banbury BR batch at each oil level.

Just as with regular butyl rubber, there is no official classification system for halobu-tyl rubber. However, these polymers are commonly classified by their Mooney viscosity value (ASTM D1646), and amount and type of halogenation and unsaturation. 

There is no official standard classification system for different grades of nitrile rubber. Commonly the percent acrylonitrile (ACN) and the Mooney viscosity value (which crudely relates to average molecular weight by ASTM D1646) are used to classify an NBR. Even with this, however, it is very possible that two sources of NBR with the same ACN content and the same Mooney viscosity will still process very differently and impart quite different physical properties to a rubber compound. 

Silicone rubbers have Mooney viscosity values typically in the 35-50 range when measured at room temperature. This is why it is unnecessary to heat silicone rubber in order to obtain good flow characteristics during shaping processes. However, for processors more used to handling organic rubbers, silicone is softer and usually more prone to collapse—for example, in thin section extrusions. 

In all of the rheometer testing of the uncured compounds, the commercial silica AZ showed the highest values with the B1 and B3 samples having the highest values among the B-series silica samples. The Mooney viscosity at 100°C increases as the number of particles in the aggregates increases. The same compounds were cured and tested, measuring tensile properties, tear resistance. 

The Delta Mooney (A Mooney) test is an extension of the Mooney used on empirical grounds as a general indication of processibility for non-pigmented oil extended emulsion styrene/butadiene rubber. It quantifies the changes that occur in Mooney viscosity with time, either as the difference between viscosities recorded at two specified times or as the difference between the minimum viscosity recorded immediately after the commencement of the test and the subsequent maximum viscosity. Several alternative Delta Mooney values are defined depending on the times, whether minimum/maximum viscosity difference is used and whether or not the sample has been massed on a mill. Procedures for Delta Mooney are standardised in ISO 289-341, BS 903 Part A58-142 and in ASTM D334643. 

Nakajima and Hamel50 have derived expressions for calculating shear stresses from the Mooney torque values to give viscosities in agreement with those obtained from other instruments, and also an expression to correct for the edge effects.51 Bristow52 derived non-standard Mooney parameters for natural rubbers to improve the distinction between different grades. 

Molecular weights are not often measured directly for control of production of polymers because other product properties are more convenient experimentally or are thought to be more directly related to various end uses. Solution and melt viscosities are examples of the latter properties. Poly(vinyl chloride) (PVC) production is controlled aceording to the viscosity of a solution of arbitrary concentration relative to that of the pure solvent. Polyolefin polymers are made to specific values of a melt flow parameter called melt index, whereas rubber is characterized by its Mooney viscosity, which is a different measure related more or less to melt viscosity. These parameters are obviously of some practical utility, or they would not be used so extensively. They are unfortunately specific to particular polymers and are of little or no use in bringing experience with one polymer to bear on problems associated with another. 

In some foods, a thin layer of low-viscosity fluid forms at the solid-fluid interface that in turn contributes to lower viscosity values. The boundary condition that at the solid-fluid interface the fluid velocity is that of the wall is not satisfied. This phenomenon is known as slip effect. Mooney (1931) outlined the procedures for the quantitative determination of slip coefficients in capillary flow and in a Couette system. The development for the concentric cylinder system will be outlined here for the case of the bob rotating and details of the derivation can be found in Mooney (1931). 

Mooney viscosity is an important process parameter and each batch of raw polymer should conform to the requisite value of Mooney viscosity, before it is released for further processing. 

Physical test properties on some cured rubber stocks prepared from lithium-catalyzed butadiene polymers are listed in Tables V and VI with appropriate controls. The results are only roughly indicative of the potential properties of rubbers made from lithium-catalyzed butadiene polymers because of the limited quantity of polymer available. The tensile data in Table VI indicate that compounded stocks from the lithium polymers are about equal or slightly inferior to the emulsion and sodium polymer controls in regard to these properties however, a hot tensile (lOO C.) on a cured compound from lithium polybutadiene was 325 pounds per square inch compared to 200 to 250 for an emulsion polybutadiene control. The internal friction of cured stocks from the lithium-catalyzed butadiene polymers is similar in magnitude to the emulsion or sodium polymer controls at 50 C. but higher at 100 °C. All lithium polymers, even those with low Mooney viscosities, gave cured compounds with high values of dynamic modulus. 

Veith [l. j reviewed the current state of precision testing using some ASTM test methods in the rubber manufacturing industry in 1987, Mooney viscosity (ISO 289. ASTM D1646), a widely used test for quality assessment of raw rubbers, gave reasonably good relative precision. Type 1 (r) pooled values of 3,0 percent for several clear rubbers, and good pooled R) values of 3,8 percent on the same basis. See Annex D for the definition of Type 1 and 2 precision and (r) and (/ ), For a widely used rate-of-cure... 

Elastomer Halogenating agent Halogen content (average value) Scattering by halogen compounds, mass % Mooney viscosity at 125 =C... 

Figure 5. Values of Mooney viscosity ML and torque MB for the SBR compounds filled with 50 phr of different types of carbon black (PM-15, PGM-33, N-550, N-330 and N-220) at different rotors revolutions (2, 3,4 min-1).

The effect of filler loading on Mooney viscosity of the rubber compound is a good indication of the immobility and hydrodynamic effect caused by the filler in the unvulcanized rubber. Figure 3.8 shows a plot of Mooney viscosity against volume fraction of filler in the vulcanizate base for data shown in Table 3.3. The theoretical value was calculated using Equation (3.12). This equation is an extension of Einstein s equation. Einstein studied colloidal suspensions and emulsions by hydrodynamic analysis. The viscosity of the... 

Effect of filler (ISAF) loading on Mooney viscosity of NR compounds - comparison between theoretical and experimental values. 

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