Ozone Aging Test Chamber to Evaluate Rubber Aging Performance

Ozone Aging Test Chamber is an experimental instrument for evaluating rubber aging. The structural changes of rubber during the thermal oxidative aging process can be divided into two categories: one is the thermal oxidative aging reaction (cracking) with molecular chain degradation as the main reaction; the other is the thermal oxidative aging (structuring) with molecular chain crosslinking as the main reaction.
  Natural rubber contains isoprene rubber, butyl rubber, EPDM rubber, homopolymerized epichlorohydrin rubber and copolymerized epichlorohydrin rubber. The appearance of this type of rubber after thermal oxidative aging is soft and sticky.
     Butadiene rubber Rubber containing butadiene mainly undergoes crosslinking reaction during thermal oxidative aging. Similar rubber varieties include NBR/SBR/CR/ERDM/FPM/CSM. The appearance of this type of rubber after thermal oxidative aging is hard and brittle.
Ozone aging test chamber to evaluate rubber aging performance
1. The main factors affecting rubber aging are:
     (1) Oxygen: Oxygen reacts with rubber molecules in rubber in a free radical chain reaction, causing molecular chains to break or over-crosslink, resulting in changes in rubber properties. Oxidation is one of the important causes of rubber aging.
     (2) Ozone: Ozone is much more chemically active than oxygen and is more destructive. It also causes molecular chains to break, but the effect of ozone on rubber varies depending on whether the rubber is deformed or not. When acting on deformed rubber (mainly unsaturated rubber), cracks appear in the direction of stress, which is the so-called "ozone cracking"; when acting on deformed rubber, only an oxide film is formed on the surface without cracking.
     (3) Heat: Increasing the temperature can cause thermal cracking or thermal crosslinking of rubber. However, the basic role of heat is activation. Increasing the oxygen diffusion rate and activating the oxidation reaction, thereby accelerating the oxidation reaction rate of rubber, is a common aging phenomenon - thermal oxidation aging.
     (4) Mechanical stress: Under the repeated action of mechanical stress, the rubber molecular chain will break to generate free ions, triggering an oxidation chain reaction and forming a mechanochemical process. Mechanical rupture of molecular chains and mechanical activation of oxidation processes. Which one will prevail depends on the conditions. In addition, ozone cracking is easily caused under stress.
     (5) Water: Water has two effects: Rubber is easily damaged when exposed to humid air or soaked in water for a long time. This is because water-soluble substances and hydrophilic groups in rubber are extracted, dissolved, hydrolyzed or absorbed by water. In particular, the alternating effects of water immersion and atmospheric exposure will accelerate the destruction of rubber. However, in some cases, water does not damage rubber and may even delay aging.
    (6) Oil: If it is in contact with oil medium for a long time during use, the oil can penetrate into the rubber and cause it to swell, resulting in a decrease in the strength and other mechanical properties of the rubber. The reason why oil can cause rubber to swell is that after the oil penetrates into the rubber, the molecules diffuse with each other, causing the network structure of the vulcanized rubber to change.
    (7) Other factors: Other factors that affect rubber include chemical media, variable valence metal ions, high-energy radiation, electricity and biology.
2. Rubber aging protection methods:
    Since rubber aging is a complex and comprehensive chemical reaction process, and it is impossible to prevent rubber aging, appropriate measures can be taken to slow down the aging of rubber, thereby achieving the purpose of extending the service life of rubber. Anti-aging measures mainly include physical protection and chemical protection.
     Physical protection refers to avoiding the interaction between rubber and various aging factors as much as possible, such as using surface coating or treatment, adding light shielding agent, adding paraffin, etc.