Rheology Mooney viscosity

Several performance characteristics of rubber such as abrasion resistance, pendulum rebound, Mooney viscosity, modulus, Taber die swell, and rheological properties can be modeled by Eq 7.34. " A complex mathematical model, called links-nodes-blobs was also developed and experimentally tested to express the properties of a filled rubber network system. Blobs are the filler aggregates, nodes are crosslinks and links are interconnecting chains. The model not only allows for... 

In addition to Mooney viscosities, the rheological properties of raw natural rubber samples were determined at 100 C using the Monsanto Processability Tester (MPT) with a die of 2,01 mm diameter (L/D ratio = 16). Elongational properties were simply estimated at 22°C, using a tensile tester and dumbbell samples die-cut from compression moulded sheets. 

In order to describe rubber compounds from the point of view of their processing capabihty different methods are used [29]. In this respect full characterization is achieved by analyzing the flow curves of rubbers and rubber compounds. The flow curves can be obtained by different viscometers. In the rubber industry (over 100 years) a technological index has been widely used - the Mooney viscosity. It serves for a comparison and control. It is measured relatively quickly with the respective viscometer and in accordance with the International standard ISO 289-1 2002. The obtained Mooney viscosity gives information just for one point of the flow curve of the rubber or rubber compound and this is the reason that no full rheological characteristics of the elastomeric material are obtained [30]. In order to describe the processing capability of rubber compounds by means of Brabender Plasticorder, the measurements are usually performed at a relatively high... 

Zheleva D. An Attempt for Correlation between Mooney Viscosity and Rheological Properties of Filled Rubber Compounds. J. Chem. Technol. Metallurgy (UCTM), 2013, vol.48, JV23, 241 -246. 

The rheological performance of rubber blends manifests the ease or diiSculty of their fabrication. Mooney viscosity measurement is usually used to determine the rheological behaviour of an uncured batch at a specific temperature. Other rheometers like plate-plate or capillary may be used for rheological characterization. 

There are several techniques for studying rheological properties, but in this chapter we present the two techniques for rheological characterization that are used to determine the flow properties of the natural rubber reactive blending. First, the Mooney viscosity can determine the natural rubber that is related directly to the inherent property of its molecular weight. It is the most common instrument used to measure the bulk viscosity of rubber. It is defined as the shearing torque that can resist the rotation of a cylindrical metal disk/rotor... 

Under different deformation conditions, natural rubber (NR) may exhibit predominant viscous flow, elastic or viscoelastic behaviour. Thus, the time for the movement of the NR molecular chains, i.e. relaxation time, is vastly affected by those deformation rate and NR types. The variation of NR types such as smoked rubber sheet, rubber blocks such as skim block, STR 5L and STR 20, is another factor that influences rheological properties and processing of NR due to their different Mooney viscosity, molecular weight distribution and gel content. Types of NRs are based on the different production processes of NR in which rubber smoked sheets are produced from NR in the latex form whereas block types are produced from various types of NR sources such as from latex in the case of STR 5L, from rubber scrap in the case of STR 20 and from skim latex in the case of skim block. 

Mooney viscosities of MNR-ADS blends were found to be much higher than those of MNR-STR 5L blends. Rheological measurements were carried out the same method as described above.The apparent values of shear stress, shear rate and shear viscosity were calculated using the derivation of the Poiseuille law for capillary flow as shown in Equations (18.1) to (18.3). Plots of the apparent shear stress versus apparent shear rate for various blend compositions of MNR-STR/STR 5L and MNR-ADS/ADS were shown in Figures 18.32 and 18.33, respectively. Straight lines of the flow curve were observed for all sets of the test. The results corresponded to the power law equation proposed by Ostwald as shown in Equation 18.4. 

The melt rheological behaviour in terms of Mooney viscosity, apparent shear stress, and apparent shear viscosity at 100 of two types of blends that included a blend between maleated STR 5L (MNR) and cassava starch and a... 

The viscosity of CPE is typically influenced by a combination of die molecular weight of the starting polyethylene and the level of chlorine added to the polyethylene. The combination of these factors contributes to the viscosity of the CPE, as measured by such tests as Mooney viscosity or capillary rheology. In general, the viscosity of CPE is controlled by the combination of the polyethylene feedstock molecular weight and the amount of chlorine added to the polyethylene backbone. However, other factors can affect the viscosity such as the MWD of the polyethylene, additives in the final CPE product, and the presence of residual crystaUinity. 

The rheological behaviour of NBR and of NBR compounds loaded with carbon black is discussed by Nakajima and Collins.According to these authors the viscoelastic behaviour of amorphous rubbers can be described by a master curve (temperature/time, pressure/time, stress/time) which permits conclusions as to the processing behaviour of these rubbers on mixing mills. Bittel has reported that the Monsanto processability tester is able to distinguish between NBR grades which are equal in Mooney viscosity, but have different shrinkage tendencies, and also that it is able to indicate the state of mix. 

The type of chosen polymer and additives most strongly influences the rheological and processing properties of plastisols. Plastisols are normally prepared from emulsion and suspension PVC which differ by their molecular masses (by the Fickentcher constant), dimensions and porosity of particles. Dimensions and shape of particles are important not only due to the well-known properties of dispersed systems (given by the formulas of Einstein, Mooney, Kronecker, etc.), but also due to the fact that these factors (in view of the small viscosity of plasticizer as a composite matrix ) influence strongly the sedimental stability of the system. The joint solution of the equations of sedimentation (precipitation) of particles by the action of gravity and of thermal motion according to Einstein and Smoluchowski leads 37,39) to the expression for the radius of the particles, r, which can not be precipitated in the dispersed system of an ideal plastisol. This expression has the form ... 

All the above formulas are one-parameter equations, i.e. they relate the dispersion viscosity only to the volume fraction of particles contained in it. This limits the range of applicability of the equations to not very high dispersion concentrations. To take account of the influence of the structure of concentrated dispersions on their rheological behavior, Robinson [12] suggested that the viscosity of dispersions is not only propertional to the volume fraction of solid phase, but is also inversely proportional to the fraction of voids in it. (At about the same time Mooney [40], who proceeded from a hydrodynamic model, arrived, using theoretical methods, at the same conclusion). Robinson s equation contains the relative sedimentation volume value — S, which depends on the particle size distribution of the dispersion... 

Rheological characterization, which wonld include measurement of compound viscosity using a Mooney Viscometer, indicating ease of processing, vulcanization and curing kinetics, and rheological information obtained from a capillary rheometer. 

The viscosity of a colloidal dispersion is a rheological property that measures the resistance to flow in response to the applied shear force. It is dependent on the hydrodynamic interactions between the particles and the continuous aqueous phase and interparticle interactions. The viscosity increases exponentially with increasing total solids content of the emulsion polymer, as shown schematically in Figure 1.7. This general feature can be described by the Mooney equation [73] ... 

In the smdy of mechanical properties of particulate filled polymers, numerous models were developed to predict the effect of the particles on tensile or shear modulus. Most of these were derived from rheological models such as Einstein s, Eilers and Mooney s equations. A strong relationship exists between rheology and mechanical properties measurements and such correlations were studied by Gahleitner et al [66], as well as by Pukansky and Tudos [67]. There seems to have a direct relation between viscosity and shear modulus [59]. However, compensation has to be taken for matrix s Poisson ratio which is lower than 0.5 as shown by Nielsen and Landel [59]. Nevertheless, these equations on modulus predictions can be broadly classified under two groups. 

A range of thiuram secondary accelerators is evaluated in an ENB-based EPDM compound and in a new technology EPDM compound. The recipes used are fairly basic, utilising CV and EV vulcanisation systems. The rheology is tested on an MDR rheometer and the compound viscosity and scorch tested on a Mooney viscometer. Stress-strain properties are established after cure at 160 deg.C and after ageing at 100 deg.C. In addition, tear properties and compression set values at various temperatures are determined. The observed... 

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