What are the reasons for the yellowing of the surface of the Automotive Wiring Harness Protection Sleeve?

The Automotive Wiring Harness Protection Sleeve is cold and high temperature resistant. But why does the food-grade Automotive Wiring Harness Protection Sleeve turn yellow after being placed at a high temperature of 200°C for 4 hours? What are the reasons for the yellowing of the surface of the Automotive Wiring Harness Protection Sleeve?

1. The amount of platinum-catalyst is too much or the platinum-catalyst is unqualified.
2. The hydroxyl content of the Cable Sleeve rubber is too much, and it is aged at high temperature.
3. The Cable Sleeve glue contains xylene and other foreign matter.
4. There is sulfur or sulfur carrier in the environment.
5. In terms of technology: the mold temperature is too high and the vulcanization time is too long.
6. Vulcanizing agent: Ordinary vulcanizing agent is used in some non-exposed Cable Sleeve products with darker color or less demanding color; high product. The Automotive Wiring Harness Protection Sleeve cannot add too much internal mold release agent and zinc stearate. If the iron content in it is too high, it will also cause yellowing.