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Sahithyan's S1 -- Properties of Materials

Degradation of Polymers

Change in the chemical and/or physical structure of the polymer chain.

Degradation is undesirable during use but desirable after use (as in biodegradation).

Types of degradations

Type of degradationAgent
Thermal degradationHeat
Chemical degradationChemical
Photo-degradationUV & other radiations
Mechanical degradationStress
BiodegradationBacteria and other organisms

Susceptibility to degradation

Depends on its structure and the type of degradation.

  • Chains containing aromatic functionality are suspectible to ultraviolet degradation
  • Hydrocarbon-based polymers are susceptible to thermal degradation

Bond rupture or scission

Breaking into smaller polymer chains. Molecular weight of the polymer decreases.

Swelling & dissolution

Main form of degradation when a polymer is exposed to liquids.

Swelling

The liquid or solute diffuses into the polymer. Polymer absorbs the liquid or solute. Chain separation increases. Secondary inter-molecular bonding forces decreases.

Dissolution

Extreme state of swelling. Occurs when the polymer is completely soluable.