Polymer Degradation

Degradation means uncontrolled reduction of molecular weight. It also means the rupture of chemical bond. And for this degradation the polymer looses its luster and stability.

Physical degradation:

1. Thermal degradation.
2. Mechanical degradation.
3. By ultrasonic waves degradation.
4. Photo degradation.
5. By light energy radiation.

Thermal degradation: It may be affected the groups joined to C-C bonds the aromatic branching and the presence of oxygen atom in the polymer chain which causes polymers to thermal degradation.

Mechanical degradation:

1. When a polymer dissolved in a solvent and subjected to vigorous stirring or beating and undergoes consideration molecular degradation.
2. In the rubber industry rubber is masticated by passing it through two rotating rollers to reduce its molecular weight the mastication converts hard and tough rubber into a soft, supple.
3. The larger the initial molecular weight, the greater the molecular weight drop due to mechanical degradation.

Photo degradation:

1. Free radicals are formed during photo-degradation and the reaction of free radicals depends on the physical state of polymer.
2. Photo stabilizer protects polymers from the deteriorating effect of light. The function of photo stabilizer is to absorb the ultra violate radiation.

Light radiation: X-ray, gamma rays, alpha and beta rays are among the well known high energy radiation.
Types of Degradation: Degradation are two types. They are:
a. Chain-end degradation.
b. Random degradation.