What changes will occur in the appearance of silicone rubber products after aging (such as discoloration, fading)?

1. Color change
Color darkening
When silicone rubber products are exposed to high temperatures for a long time, the organic compounds inside may undergo oxidation reactions. These additives will generate some colored substances during the oxidation process, causing the color of silicone rubber to darken. For example, in some industrial production environments, silicone rubber products used for sealing high-temperature equipment may gradually turn from white to light yellow or brown after several months of use.
Ultraviolet radiation is also an important factor in causing discoloration of silicone rubber. The energy of ultraviolet radiation can cause certain chemical bonds in the molecular chain of silicone rubber to break, generating free radicals. These free radicals further trigger a series of chemical reactions, producing conjugated colored substances. Like some outdoor silicone rubber sealing strips, long-term exposure to sunlight will gradually darken the surface color, from light to dark.
Yellow color
This is mainly due to the chemical changes that occur during the aging process of additives in silicone rubber, such as certain organic silicone oils or silicone resins. These additives may undergo yellowing reactions, causing the entire silicone rubber product to appear yellowed. For example, some silicone rubber gaskets used in electronic devices may turn yellow during long-term operation due to the combined effects of internal heat and external light.

2. Fading
If dyes and other coloring agents are added to silicone rubber products, these coloring agents may gradually decompose or be lost during the aging process. For example, some colored silicone rubber toys may gradually become dull and even show obvious fading after prolonged use and sun exposure. This is because the dye molecules in toys undergo changes in their chemical structure and color characteristics due to factors such as light and heat, ultimately leading to fading.