The dispersibility of the nano-filler in the rubber matrix has a decisive influence on the comprehensive properties of the rubber compound, and effectively improves the dispersion of the nanoparticles in the rubber, which is the key to developing high-performance tire rubber compound. Epoxidized natural rubber (ENR) is a product of natural rubber (NR) modified by epoxidation. Nano silica (white carbon black) is added to ENR without using any coupling agent. The interaction between the epoxy group on the ENR molecular chain and the silanol on the surface of the silica (hydrogen bond or chemical bond) inhibits the agglomeration of the silica and allows the silica to be homogeneously dispersed in the rubber matrix to enhance the adhesion. Material performance.

The application of silica in epoxidized natural rubber (ENR) without the use of any coupling agent was investigated. The white carbon black undergoes significant agglomeration in natural rubber (NR), and the agglomeration in the ENR can be significantly improved, and the higher the degree of epoxidation of the ENR, the better the dispersion of the white carbon black. ENR white carbon black compound exhibits good wet skid resistance and low rolling resistance. When the amount of white carbon black is more than 20 parts, the compressed heat of ENR/white carbon black rubber is significantly lower than that of NR/carbon black rubber. .
The white carbon black has obvious agglomeration in the NR compound. When the amount of white carbon black is more than 20 parts, a large amount of aggregates appear in the rubber compound. This is because silica has a very large surface energy, and the surface of the particles contains a large amount of silanol groups, and the dispersion of white carbon in NR is poor without using any coupling agent. In the ENR compound, the agglomeration of white carbon black is significantly improved due to the introduction of epoxy groups in the NR molecular chain. The white carbon black is homogeneously distributed in the ENR matrix, and the white carbon black in the ENR40 compound is dispersed. The situation is better than ENR25 compound, indicating that the higher the content of ENR epoxy group, the better the dispersion of white carbon in ENR.
Dynamic mechanical performance analysis
After partial double bond epoxidation modification in the NR molecular chain, the molecular chain flexibility is lowered and the glass transition temperature (Tg) is increased. The rubber loss factor (tan δ) of NR and ENR of silica was not added.
The tan δ of the rubber at 0 °C increases with the degree of oxidative modification of ENR, indicating that the dynamic hysteresis loss of the rubber becomes larger and the wet skid resistance is improved. The tan δ (characterization of wet skid resistance) of ENR25 and ENR40 compounds at 0 °C is greater than that of NR compound. The tan δ (characterized rolling resistance) at 60 °C is less than NR, indicating that the wet skid resistance and rolling resistance are simultaneously improved.
After the addition of silica, the anti-slip performance of ENR40 compound is better than that of NR compound. The rolling resistance of ENR25 is less than that of NR compound. When the amount of white carbon black is 20 parts, the rolling resistance of ENR40 compound is equivalent to that of NR compound. When the degree of epoxidation of the white carbon rubber is increased, the compression heat generation of the rubber compound is increased, which is because the NR molecular chain contains a large number of double bonds, the molecular chain has good flexibility, and the frictional internal friction between the molecular chains is low; When the double bond on the rubber molecular chain is modified into an epoxy group, the flexibility of the molecular chain is lowered, and the internal frictional friction between the molecular chains is increased. Therefore, the heat generation of the rubber increases as the degree of epoxidation of the rubber increases. With the addition of silica, under the dynamic stress-strain condition, the relative motion between the rubber macromolecular chains of the rubber compound, the rubber molecular chain and the filler particles, and the filler particles is not synchronized due to the rubber molecular chain. The friction between the two is a slight inter-structure friction. The friction between the filler particles belongs to at least the nano-particle friction. In contrast, the addition of the filler makes the friction more intense, which leads to a substantial increase in the overall dynamic heat generation of the rubber compound. The influence of filler on the dynamic properties of the rubber is mainly from the following two aspects: the contact interface between the filler and the rubber molecule and the amount of filler. Generally speaking, the smaller the particle size of the filler, the larger the specific surface area, the larger the surface energy, the more likely to agglomerate to reduce the surface energy, the more difficult the dispersion after the agglomeration of the filler, the worse the dispersibility, the more the dynamic properties of the rubber compound It is not good, the heat is generated, the more easily the interior of the product is destroyed by high temperature ablation during use; the larger the amount of filler, the more friction between the filler particles and the rubber molecules, and the greater the dynamic heat generation.
As the amount of white carbon black increases, the heat of compression of the NR/white carbon black compound increases rapidly. This is due to the serious agglomeration of the white carbon black in the NR compound. Under the dynamic action, the friction between the fillers Dominant. When the amount of silica is 20 parts, the NR compound generates more heat than the ENR25 compound and is lower than the ENR40 compound. Under the condition of not using any coupling agent, the white carbon black undergoes significant agglomeration in the NR matrix. The introduction of epoxy groups in the NR molecular chain significantly inhibits the agglomeration of silica, and the higher the content of epoxy groups, the better the dispersion of silica. ENR/white carbon black compound has good wet skid resistance and low rolling resistance; after the amount of white carbon black is more than 20 parts, the compressed heat of ENR/white carbon black compound is significantly lower than NR/white carbon black. Rubber compound, which is of great significance for high performance green tires.