Fotodegradointi

Fotodegradointi is a Lithuanian verb meaning to photodegrade. In scientific contexts, it corresponds to photodegradation, the chemical breakdown of materials under light. The process can proceed by direct photolysis, where light directly cleaves bonds, or by indirect pathways in which light excites molecules that generate reactive oxygen species, leading to oxidation and fragmentation. Common targets include polymers (polyolefins, polyesters), dyes, pesticides, and pharmaceuticals. Photodegradation alters color, mechanical properties, and molecular structure, and can yield small volatile compounds or persistent residues depending on conditions.

Factors influencing fotodegradointi include light wavelength and intensity, exposure duration, presence of oxygen, humidity, and temperature; material properties (molecular weight, crystallinity, UV stabilizers, pigments) and environmental context (surface vs bulk, film thickness, contaminant presence). Catalysts such as titania or other photosensitizers can accelerate photodegradation.

Methods to study fotodegradointi involve laboratory weathering devices (UV chambers, solar simulators) to simulate sunlight exposure; analyses include UV-Vis spectroscopy for changes in absorption, FTIR for functional-group changes, GPC for molecular-weight distribution, and mass spectrometry for degradation products.

Applications and implications cover the assessment of durability of plastics, coatings, and textiles; modeling environmental fate of pollutants; and guiding the development of stabilizers and more photoresistant materials. Environmental concerns include the formation of toxic or persistent degradation products and microplastics.

Note: In Lithuanian literature, fotodegradointi is used as a verb; the noun is fotodegradacija.