The effect of exposure to Pyrinex 480 on the degradation of clear oxodegradable polyethylene agricultural films

Oxodegradable agricultural films must have predictable lifetimes if benefits associated with their use are to be maximized. This paper presents results examining the change in degradation of oxodegradable films upon exposure to a commonly used insecticide, Pyrinex 480. Pieces of oxodegradable agricultural film, both untreated and treated with different doses of this pesticide in the range of 3.0-10.6 ± 0.5 mg/m2 of film, were placed in a field environment, gravity ovens at 60, 70 and 80 °C, and an accelerated aging environment that included elevated temperature and exposure to UV light. Degradation of the films was inferred from carbonyl index values calculated using measured infrared absorbance spectra of films collected as a function of exposure time. A delay in oxidation was observed in films treated with Pyrinex 480 relative to untreated films. This delay was most pronounced in environments that included exposure to light. Measurement of the UV absorbance of the pesticide and measurement of its ability to act as a chain-breaking donor or acceptor suggest that Pyrinex 480 achieves its effect on degradation by acting as a UV screener, which has important implications for the use of this type of film where pesticide exposure may be encountered.