What are the reasons and solutions for the structural phenomenon of the Automotive Wiring Harness Protection Sleeve?

The general steps in the production of Automotive Wiring Harness Protection Sleeve are natural rubber treatment--formulation according to the needs of use-mixing on the rubber mixer-parking (about 24 hours)-remelting-making semi-finished products-vulcanization-trimming- -test. But this problem will be encountered when mixing rubber, and the cable casing is structured. The following is an analysis of the reasons for the structuralization of the Automotive Wiring Harness Protection Sleeve and its control methods.

The structuralization of the Cable Sleeve means that the Automotive Wiring Harness Protection Sleeve reinforced with white carbon black will harden during storage, reduce the plasticity, and gradually lose the processing performance. This phenomenon is called the "structural" effect. The already structured cable jacket compound needs to be re-mixed or heat-treated to eliminate this phenomenon, but the process cost will increase.
The reason for the structural phenomenon: one theory is that the active silanol groups on the surface of the silica particles condense with the silanol groups at the end of the raw rubber molecules at room temperature, resulting in hardening of the Cable Sleeve and a decrease in plasticity; the other is that It is said that the Si-OH group on the surface of the silica interacts with the Si-O bond or the terminal Si-OH group of the raw rubber molecule to form a hydrogen bond, and even chemically combines, so that the linear polysiloxane is transformed into a pseudo-crosslinked or micro-crosslinked. The semi-elastic solid structure of the joint, so the Cable Sleeve becomes hard and the plasticity is greatly reduced.
One is to add "structural control agent", silicone oil or silane, silicone resin, etc. with active groups, which is the most commonly used method in production. For example, adding a certain amount of hydroxyl silicone oil, silazane, etc., can have a good structural control effect; the mechanism is that substances such as silicone oil with active groups undergo condensation reactions with active hydroxyl groups on the surface of silica, thereby Interaction between silica and raw rubber is prevented.
2. Surface treatment of white carbon black, such as using silane coupling agent, hexamethyldisilazane, etc. to treat white carbon black, can also prevent the structure of the cable casing rubber compound. The mechanism is that the surface of silica has been wrapped by coupling agent or silazane, and the surface active groups of silica have been shielded, thus preventing the interaction between silica and raw rubber.
In addition, if the surface treatment of silica is to be carried out on the protective cover of Automotive Wiring Harness Protection Sleeve, structure control agent and hydroxyl silicone oil must be added, which should have a certain influence on the performance. Because structuring is a process in which hydrogen bonds are formed slowly, the key lies in how to control the formation of hydrogen bonds. Silica treatment is a good way, but the cost is too high. The current common method is to use hydroxyl silicone oil, but only additives are not enough Yes, it is also necessary to take process control in the production process.