Payne effect dispersion

The incorporation of reinforcing hllers into rubber results in most cases in an increase of the storage and loss moduli, G and G", and an increase in hysteresis, as quantihed by the loss angle 8, where tan 8 is C jG. When properly dispersed and coupled to the mbber matrix via a coupling agent, as represented by a low Payne effect, silica also shows less hysteretic loss at elevated temperatures. 

Compounds containing PA-silica, PTh-silica, or silane-treated silica show the lowest reinforcement parameters in this series. This indicates a good dispersion of the polymer and a low degree of filler-filler interaction, as also shown by the Payne effect values. 

For silica in SBR, a polyacetylene coating gives the lowest filler-filler interaction, a good filler-polymer interaction, and the best dispersion compared to untreated and the other plasma-treated samples. However, for the stress-strain properties, the polythiophene-treated sample gives the best results. This shows the importance of sulfur moieties on the surface of the filler, which form a secondary network in the cured materials. In the blend of S-SBR and EPDM rubbers, the situation is less conclusive. The Payne effect, the bound rubber, and... 

Even dynamic measurements have been made on mixtures of carbon black with decane and liquid paraffin [22], carbon black suspensions in ethylene vinylacetate copolymers [23], or on clay/water systems [24,25]. The corresponding results show that the storage modulus decreases with dynamic amplitude in a manner similar to that of conventional rubber (e.g., NR/carbon blacks). This demonstrates the existence and properties of physical carbon black structures in the absence of rubber. Further, these results indicate that structure effects of the filler determine the Payne-effect primarily. The elastomer seems to act merely as a dispersing medium that influences the magnitude of agglomeration and distribution of filler, but does not have visible influence on the overall characteristics of three-dimensional filler networks or filler clusters, respectively. The elastomer matrix allows the filler structure to reform after breakdown with increasing strain amplitude. 

Based on these models one would expect disulfide silanes, and moreover tetrasulfide silanes to build a hydrophobic surface, providing excellent dispersibility and low silica-silica interaction (resulting eventually in a lower Payne effect). The rheology study suggests the contrary. 

Crosslinked NR nanocomposites were prepared with montmorillonite. Morphology was characterized using transmission electron microscopy (TEM), wide-angle X-ray scattering (WAXS), and dynamic mechanical analysis (DMA). X-ray scattering patterns revealed clay intercalation and TEM showed dispersion with partial delamination. The loss modulus peak broadened with clay content, while Tg remain constant. Montmorillonite reinforced the rubber. The DMA exhibited non-linear behaviour typified as a Payne effect (see Section 20.11) that increased with clay content and was more pronounced for this type of nanocomposite. Viscoelastic behaviour was observed under large strains via recovery and stress relaxation. ... 

Non-linear mechanical properties were observed for rubber eomposites and referred to as the Payne effect. The Payne effeet was interpreted as due to filler agglomeration where the filler clusters formed eontained adsorbed rubber. The occluded rubber molecules within filler elusters eould not eontribute to overall elastic properties. The composites behaved similarly to rubber composites with higher filler loading. Uniform and stable filler dispersion is required for rubber composites to exhibit linear viscoelastic behaviour. Payne performed dielectric measurements on SBR vulcanizates containing silica or carbon black. The dielectric data were used to construct time-temperature superposition master curves. The reference temperature increased with crosslinking but not significantly with filler. Comparison of dynamic mechanical and dielectric results for the SBR blended with NR was made and interpreted. ... 

The dynamic properties of filled rubbers are widely studied by many researchers in this field of which the contribution made by Payne is the most significant. The dependence of strain amplitude on the storage modulus in filled mbbers is known as the Payne effect [27]. At a strain more than 0.1 %, the storage modulus of filled rubber collapses from a plateau value of G O to a minimum value Goo and this decrease is accompanied by a maximum of the loss modulus, G". The variation in this storage modulus value with respect to the minimum value is called amplitude of the Payne effect, and this increases with the filler content, specific surface and properties of the filler and its dispersion within the matrix. The amplitude inversely changes with temperature. A lot of investigations were performed in order to explain the Payne effect and reasons behind it. Payne neglected the contribution... 

Filler modification affects the viscoelasticity since the variation in storage modulus with strain changes with rate of dispersion. This is illustrated in Fig. 6. The unmodified fillers in mbber cause agglomeration and thus result in high Payne effect due to strong inter-aggregate interaction of filler. With modification, the Payne effect of the filled compounds changes as the filler-filler networks is... 

Fig. 6 Effect of filler aggregate (dispersion) on Payne effect...

The addition of iso-dimensional nanofillers into elastomers causes many changes in mechanical and physical properties, but especially, the effect of nanoparticles on the nonlinear viscoelasticity properties of rubbers has been investigated. In rubber matrices containing nanofillers, exhibition of the Payne effect is strongly connected with the dispersion of the nanofiller and the tendency to create aggregates among the nanoparticles. Filler dispersion plays an important role in determining the nonlinear viscoelastic behavior of these systems— in particular, both the properties of the filler particles and filler-polymer compatibility. 

The rheological properties, especially the dynamic-mechanical properties, can be very useful in predicting the dispersion of the nanofiller. In rubber nanocomposites, the observed Payne effect can be correlated with microscopic investigation, and often both these characteristics are consistent. 

After vulcanization, the chemical crosslinks network is formed, which largely enhance the mechanical properties of rubber. The poly-ZDMA nano-particles dispersed in NR matrix, yielding a pronounced Payne effect. As shown in Fig. 10, the linear viscoelastic region (LVE) of vulcanizate with high loading of ZDMA corresponded to an elastic modulus independent to deformation, which can be observed at middle strain amplitudes (even to 1°, equal to al4 %). This... 

The Payne effect [9] has been extensively investigated because it directly impacts the fuel consumption. From a phenomenological point of view, beyond a strain higher than a few 0.1 %, the storage modulus of filled rubber departs firom a plateau value Gq and collapse to a minimum value. The decrease in the storage modulus is accompanied by a maximum of the loss modulus, G". The amplitude of the Payne effect, AG) Gq — G increases with the filler content, the specific surface of the filler [12] and strongly depends on the surface properties of the fillers and its dispersion [13] within the matrix. On the contrary it decreases with temperature... 

A vulcanized sample, obtained from a reference mixture, contained mainly SBR-2 non epoxidized and precipitated silica, presents a value of the storage modulus (G ) at low amplitude of deformation, which is 4 times higher than that value showed by a mixture of SBR-2(ep7)/silica. This reduction of G shows a slightly network, due to the favorable energetically interaction between epoxy groups of the epoxidized rubber and the sUanol groups present onto the silica surface. Because of that, it is possible to have a better dispersion leading to a reduction of the Payne effect (Fig. 20). 

In silicarfilled styrene-butadiene rubbers, due to weak polymer-filler interactions, the silica network is highly developed (Figm-e 4.7c). The use of a coupling agent improves the dispersion and consequently reduces substantially the amplitude of the Payne effect and also tg 6, which is an important parameter in the rolling resistance of tires. 

The poorer the dispersion the larger the DSS (Payne effect). Indeed as shown in Figure 5.39, the elastic modulus drop with increasing strain amplitude tends to decrease as mixing duration increases. But DSS still exists for optimally dispersed compound, as may be expected with respect to curves in the Figure 5.38 which tend to be closer each other as mixing time increases. Such observations are somewhat contradictory with the simple "filler network" interpretation offered by Payne for the strain dependent modulus. Indeed, as the dispersion of CB particles improves, the spatial influence of any expected filler network should widen and the... 

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