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The oxidative deterioration and oxidative degradation of polymers, rubbers, elastomers used in tires has been described in the literature and accepted by the scientific community[i] .

“oxidative degradation accelerates the aging of the rubber”

Oxidative degradation of polymers is a chemical reaction of a polymer with oxygen (either as oxygen molecule O2 or as Ozone molecule O3) that destroys the main structure of rubber and reduces its lifespan[ii]. In other words, the oxidative degradation accelerates the aging of the rubber. It is mainly caused by chemical bond scission or bond cleavage reactions in macromolecules of either the main chains or the crosslinks, if present.

Recent studies have established that the lifespan of rubber is enhanced considerably if for tires inerted with nitrogen, compared to those inflated with air (which is one-fifth oxygen by volume).

The more advanced pneumatic tires manufactured these days use layers of thermoplastic resin laminated as an inner liner to prevent oxygen molecules from reaching rubber molecules. This technique is designed to protect the inner surface of polymer (rubber) from oxidative deterioration or oxidative degradation. While it is an effective strategy, it makes tires considerably more expensive.

Research[iii] has shown that oxidative degradation of pneumatic tires is effectively suppressed with an oxygen absorbent trapping agent, and therefore, can increase the durability of pneumatic tire.

Again, the approach can prolong the life of a tire by shielding the rubber from the deleterious effects of oxygen. But the cost of manufacturing the tires is quite a bit higher.

A simpler approach is to inert tires with nitrogen instead of inflating them with air, removing oxygen from the equation altogether.

 

References:

[i] EFFECT OF NITROGEN PURITY ON THE OXIDATION OF BELT COAT COMPOUND. http://www.ardl.com/sites/default/files/docs/papers/Uday/ACS/Role%20of%20Effect%20of%20Nitrogrn%20Purity%20on%20the%20oxidation%20of%20belt%20coat%20compound.pdf

[ii] Studies of the oxidative degradation of butyl rubber in tyre inner tube https://dspace.lboro.ac.uk/dspace-jspui/bitstream/2134/7401/1/353255%5B1%5D.pdf

[iii] Pneumatic Tire Containing Oxygen Absorbent http://www.google.com.na/patents/US20070209744

 

Post Author: Dr. Mir Mohamad Mohaddes

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