# The Effect of OMMT on the Properties of Vehicle Damping Carbon Black-Natural Rubber Composites
## 3 Results and Discussion
### Mechanical Properties  
Table 2 shows the effect of OMMT addition amount (on the basis of weight) on the mechanical properties of vulcanized CB/NR polymer composites. It can be seen that the OMMT content has an adverse effect on the physical and mechanical properties of the material, especially on the tearing strength. However, the tensile strength decreased by less than 11.5%, which still met the requirements of automobile vibration reduction products. According to the tensile strength at different elongations, it can be seen that the modulus had a decreasing trend with increasing of the OMMT contents. It is worth mentioning that the composite obtained has a greater resilience by adding 2 phr OMMT, which is similar to the variation trends of M\({}_{\rm H}\) and MH-ML as discussed in the above analysis.  
Figure 1: The effects of the contents of OMMT on the cure rate index of carbon black (CB)/natural rubber (NR) composites.  
Hardness was measured at five different locations of each sample. Figure 2 shows the hardness of composite material changing with the amounts of OMMT. It can be seen that the hardness values of vulcanized rubber filled different contents of OMMT were all within \(65\pm 2\) and the general trend of it is increase slightly with more contents, but not all of it fits this pattern due to experimental mistakes. It also reflects its effect on the packing-packing network of vulcanized rubber. These data indicate that OMMT has minor influence on the vulcanized rubber hardness, which is of great importance to the formulation design of shock absorbing products.  
It can be seen from Table 3 that the final temperature rise of compression heat generation was the lowest with addition of 2 phr OMMT, and it increased gradually with increasing of OMMT amounts. When the rubber endures the cyclic stress, the macromolecular chain segment can generate relative motion, which then converts the mechanical energy into the thermal energy. It was preliminarily expected that 2 phr OMMT will reduce the agglomeration effect and improve the dispersion of CB. When excessive content of OMMT was added, the fillers were more unevenly dispersed. The filler-filler network thus became stronger and the friction between them caused the heat of rubber increased. At the same time, the static compression permanent deformation of polymer composites reduced gradually. This may be a result of the insertion of the rubber macromolecular segment into the OMMT sheet structure, which then increases the physical cross-linking and reduces the static compression permanent deformation.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**The Content of OMMT/phr** & **0** & **2** & **4** & **6** & **8** \\ \hline Tensile Strength/MPa & 27.5 & 27.6 & 25.2 & 25.6 & 24.4 \\ Elongation/\% & 616 & 502 & 519 & 515 & 488 \\ Tensile Strength at 100\%/MPa & 2.1 & 3.2 & 2.7 & 2.8 & 2.8 \\ Tensile Strength at 300\%/MPa & 11.0 & 15.0 & 12.4 & 12.9 & 13.2 \\ Elasticity Modulus/MPa & 2.6 & 3.4 & 2.9 & 3.1 & 3.2 \\ Tear Strength/kN/m & 131.9 & 111.9 & 111.3 & 96.6 & 87.0 \\ Resilience Property/\% & 47.7 & 51.9 & 51.4 & 52.0 & 51.4 \\ \hline \hline \end{tabular}
\end{table}
Table 2: The effects of OMMT contents on mechanical properties of vulcanized rubber.  
Figure 2: The effects of the contents of OMMT on hardness of vulcanized rubber.