Rubber aging reasons:
- 1. Internal causes:
- The molecular structure of the rubber
- Chemical structure (or chain structure): The basic structure of rubber such as natural rubber unit isoprene, there are double bonds and active hydrogen atoms, so easy to participate in the reaction.
Molecular chain structure: rubber macromolecular chain weak bond, the weak part of the more easy to aging.
- Unsaturated carbon chain rubber is susceptible to aging. The oxidative capacity of saturated carbon chain rubber is related to its chemical structure. For example, branched macromolecules are more susceptible to oxidation than linear molecules. In the case of oxidative stability, the various substituents are arranged in the following order: CH <CH2 <CH3.
- Vulcanized rubber cross-linking structure: cross-linking bond with -S-, – S2 -, – Sx -, – C-C-, cross-linked bond structure is different, vulcanized rubber aging resistance, -Sx- worst.
- Rubber compound components and impurities: Rubber often exists in the price of metal, such as Ca, Fe, Co, Ni, etc., if more than 3ppm will greatly accelerate the aging of rubber.
- 2. External cause:
- Physical factors: high-energy radiation, such as thermoelectric light.
- Chemical factors: Ozone, water and alkali in the air.
- Biological factors: Microbes: Bacterial fungi
Insects: termite cockroaches will eat high molecular material.
Sea creatures: oyster lime seaweed seaweed and so on
- The most common, most influential and destructive factors are heat, oxygen, light oxygen, mechanical force, and ozone.
Rubber aging protection
(1) the use of anti-aging properties of raw rubber varieties
(2) the use of anti-aging performance of a good curing system
(3) to join the protective additives (antioxidant)
- Physical protection law: the way to avoid the interaction of rubber and aging factors. Such as: in the rubber by adding paraffin, rubber and plastic blending, plating, coating and so on.
- Chemical Protection Act: Delayed rubber aging by chemical reaction continues. Such as adding chemical antioxidants.