Oxidation In Polymers

Oxidation in Polymers
A polymer is a large molecule (macromolecule) composed of repeating structural units. These sub-units are typically connected by covalent chemical bonds. Although the termpolymer is sometimes taken to refer to plastics, it actually encompasses a large class of compounds comprising both natural and synthetic materials with a wide variety of properties.
Oxidation isdefined as the interaction between oxygen molecules and all the different substances they may contact, from metal to living tissue. Technically, however, with the discovery of electrons, oxidation came tobe more precisely defined as the loss of at least one electron when two or more substances interact. Those substances may or may not include oxygen.
The degradation of the polymers, it takes placeduring his manufacture or transformation.
During the polymerization, the process of combining many small molecules known as monomers into a covalently bonded chain or network, for the production ofplastic they control initiators and catalysts; these cannot be eliminated completely in the stage of purification of the polymer, for what the impurities originate that the oxidation begins.
Thisis due to the fact that the radical free presents possess affinity with the oxygen of the catalyst or initiator and attract hydrogen producing unstable hyperoxides, which can react in chain with thepolymer, reaction that is not stopped until an inert group takes place.
In the transformation of the polymer, the temperatures of processing and the speed of production raised are propitiousconditions for the degradation of the material.
For any of the previous reasons, when a polymer degraded he presents:
* Discoloration or turn into yellow
* Loss of mechanical properties
*Inflexibility
* Loss of weight
The antioxidant ones are used by the producers of plastic materials who make commercial degrees for specific applications. These are used generally in Polystyrene.