Application of Silane in Clay Glue for Anti-thermal and Oxidative Aging

The coupling agent is used as a reinforcing agent and filler for rubber, which is generally devoted to improving the strength of the material. It has been reported that the use of silane coupling agents can not only greatly improve the physical and mechanical properties, but also improve the thermal aging properties of materials; while titanate coupling agents have a negative effect on aging properties. Therefore, this experiment assumes that the silane coupling agent is used to form a film on the surface of the filler to block the oxidative catalytic effect of the variable-valence metal ions contained in the clay particles on the rubber hydrocarbon, so as to achieve the purpose of improving the thermal oxidation performance of the clay glue.

1. Anti-thermal and oxygen aging effect of silane coupling agent

The change of plasticity and plasticity retention rate of clay glue blank sample, clay glue with silane coupling agent KH-550 and anti-aging agent with aging time. It can be seen that the silane coupling agent has an obvious thermal-oxidative aging protection effect on the clay glue.

2. The effect of the amount of silane coupling agent

In order to further understand the effect of the coupling agent, different amounts of KH-550 were added to the clay glue, and the prepared clay glue sample was exposed to the air for 2 months, and then test the value of the plasticity and plasticity retention of the sample with the heat aging time. The effect of adding silane coupling agent is very good. The plasticity of the blank sample without coupling agent is close to the low value after heat aging for 10 minutes, while the plasticity of the samples added with coupling agent was lower than that of the samples added with 1.0 phr. This is because when the coupling agent is added, a relatively complete monomolecular layer coating film can be formed for the clay particles, which properly blocks the effect of the metal elements in the clay particles on the rubber hydrocarbon. Many studies have reported this point, that is, when the coupling agent (to the filler mass ratio) is added, the coupling agent works very well. If the amount of coupling agent is too small, a complete film cannot be formed, and the expected effect cannot be achieved. However, too much coupling agent will have a negative effect, and the plasticity will decrease instead.

3. The synergistic effect of silane coupling agent and anti-aging agent

In order to compare the effect of silane coupling agent KH-550 on the physical and mechanical properties of the vulcanized rubber, each sample is the vulcanized clay vulcanized rubber with 1 part of KH-550; the vulcanized rubber with blank sample; the vulcanized clay rubber with 1 part of anti-aging agent; add 1 part of KH-550, and add 1 part of anti-aging agent at the same time. Test the physical and mechanical properties of the samples before and after aging.

The results show that the connection boundary between clay particles and rubber materials, that is, clay particles are only contained in rubber hydrocarbons, and there is no binding force with rubber hydrocarbons. Due to the addition of silane coupling agent, the bonding between clay particles and rubber hydrocarbons is better, and no obvious connection boundary between clay particles and rubber materials can be seen on the section. That is to say, because the two active groups of the silane coupling agent respectively interact with the filler clay particles and the rubber hydrocarbon to form bonds, so that a bonding force is generated between the clay particles and the rubber material, so the cross-section looks smoother and flatter, so the material's physical and mechanical properties are improved.

Applying the silane coupling agent KH-550 to the clay glue can not only greatly improve the strength of the material, but also have obvious anti-thermal and oxidative aging effects. At the same time, it has a good synergistic effect with the anti-aging agent.