# The Effect of OMMT on the Properties of Vehicle Damping Carbon Black-Natural Rubber Composites
## 3 Results and Discussion
### Dynamic Mechanical Performance  
In general, polymers are not used in their pure form, which means that the CB, silica and OMMT play an important role in the polymer reinforcement. The fillers in polymer strongly modifies the viscoelastic behavior, especially the dynamic mechanical properties of the composite. In dynamic mechanics measurements of shear modulus, the Payne effect is often referred to as the progressive breakdown of packing-packing interactions, where G' is used commonly [23; 24; 25]. RPA8000 was used to conduct three-dimensional strain scanning on CB/NR compounds filled with different contents of OMMT, and the interaction between packing-packing and the interaction between packing-rubber were accurately characterized. Each content was tested with three samples and the experimental results were shown in Figure 3, which indicates that the storage modulus curves of the rubber compound changed significantly with different contents of OMMT. The last two storage modulus curves were greatly lower than the first one under low strain conditions with respect to each different OMMT contents of rubber and the latter two curves were basically coincident. There were packing-packing networks in the composite which was destroyed during the first strain sweep and cannot be instantaneously recovered, and the last two measurements were performed on the basis of the completely destroyed packing-packing network. Figure 3: _Cont._ \begin{table}
\begin{tabular}{c c c c} \hline \hline
**OMMT/phr** & **Final Temperature** & **Dynamic Compression** & **Static Compression Permanent** \\  & **Rise/C** & **Permanent Deformation/\%** & **Deformation/\%** \\ \hline
0 & 15.85 & 0.060 & 0.093 \\
2 & 13.90 & 0.040 & 0.091 \\
4 & 14.25 & 0.051 & 0.083 \\
6 & 15.30 & 0.055 & 0.081 \\
8 & 15.80 & 0.045 & 0.072 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The effects of OMMT content on the compressed heat generation and compression permanent deformation of vulcanized rubber. In order to further study the dispersion of fillers in the CB/NR composites, we marked it in the RPA scans. The difference values of G'(1)-G'(3) at low strain could indicate the strength of the packing network, and the different values of G'(3)-G'(0) without adding filler at low strain could indicate the strength of the filler and the rubber [26]. It can be seen from Figure 4 that the value of G'(1)-G'(3) with 2 phr OMMT was the lowest in all composites. With adding more OMMT, the value of G'(1)-G'(3) increased progressively. When the content of OMMT was added more than 8 phr, it becomes larger than that of without OMMT. It shows that a small amount (2 and 4 phr) of OMMT induces the weaker filler-filler network, which is helpful for the dispersion of carbon black. If the content is too large, the OMMT agglomeration effect becomes stronger and the material properties decreased. The order of G'(3)-G'(0) value influenced by OMMT was \(10>8>6>4>0>2\) phr. When the content of OMMT was 2 phr, the filler-rubber interaction was lowest; the interaction of the filler was also minimized; and the MH-ML was the largest. It can be preliminarily concluded that when 2 phr OMMT added, the rubber-rubber interaction was the strongest and the performance of rubber was good. Figure 5 shows the storage modulus of the rubber compound filled with different contents of OMMT under small strain, which exhibited a nonlinear decrease with the increase of strain. This was the so-called Payne effect. Normally, the better the fillers dispersion, the lower the storage modulus under the same condition of the strain sweep. Figure 4: (**a**) G’ (1)-G’ (3) and (**b**) G’ (3)-G’ (0) of CB/NR composites with different contents of OMMT. Figure 3: The three times G’-strain curves of the CB/NR rubber composites with different contents of OMMT. The content of OMMT: (**a**) 0 phr, (**b**) 2 phr, (**c**) 4 phr, (**d**) 6 phr, (**e**) 8 phr.