Quantitative analysis of UV protective additives in polyethylene films by solvent extraction coupled with UV spectrophotometry

Commercial UV protective additives based on UV stabilizers (UVSs) and UV absorbers (UVAs) are used to enhance the durability of polymeric materials exposed to outdoor weathering, ultraviolet (UV) light, and heat, as in the case of agriculture films for greenhouses and water reservoirs. It is important to quantitatively study, analyze, and control the loss of these protective additives by migration and depletion from polymeric films under accelerated photodegradation and humid environments. In this study, an UVA (Tinuvin 326) and two UVSs (Chimassorb 944 FDL, and Chimassorb 911) were loaded separately in linear low-density polyethylene (LLDPE) film and exposed to an accelerated weathering environment with ultraviolet radiation (QUV chamber). The concentration of the additives in the film before and after accelerated weathering was determined using accelerated solvent extraction and quantitatively analyzed using UV spectrophotometry. Direct quantification by FTIR spectroscopy was used on the solid films to trace the changes in the amount of the UVA and UVSs in the films following accelerated weathering exposure. Good correlation was obtained between the two methods. Using these techniques and determining each additive's loss profile, the lifetimes of polymeric films used for agriculture applications can be predicted.