polymerdegrading

Polymer degradation refers to processes by which polymer materials lose chemical, physical, or mechanical properties due to changes in their molecular structure or morphology. Degradation can be chemical, physical, or biological, and is often irreversible.

Common mechanisms include chain scission, crosslinking, oxidation, hydrolysis, photodegradation, and mechanical fatigue. Thermal degradation involves bond breakage under heat, while oxidation adds oxygen-containing groups that weaken the material. Hydrolysis cleaves susceptible bonds (such as esters) in the presence of water. Photodegradation is initiated by light, particularly ultraviolet radiation, generating radicals that propagate chain reactions. Biodegradation is the enzymatic breakdown by microorganisms, leading to mineralization in some cases.

Rates and pathways depend on temperature, humidity, light exposure, oxygen availability, mechanical stress, polymer chemistry, processing history, and the presence of additives. Stabilizers, antioxidants, and UV absorbers can slow degradation, while fillers and crystallinity can influence it. Degradation typically lowers molecular weight and mechanical strength, increases brittleness, and can alter color and permeability.

Analytical techniques used to study degradation include gel permeation chromatography to monitor molecular weight distribution, infrared spectroscopy for functional-group formation, differential scanning calorimetry for thermal properties, and thermogravimetric analysis for stability.

Understanding polymer degradation informs materials selection, lifetime prediction, recycling, and design of degradable polymers for environmental applications.