Degradation of beeswax by NOx pollution and UV light studied by DSC and FTIR measurements
2020
Vykydalová, Anna | Cibulková, Zuzana | Čížová, Katarína | Vizárová, Katarína | Simon, Peter
This work is focused on the study of the effect of polluted atmosphere NOₓ and UV light irradiation on the thermooxidative stability of beeswax. Differential scanning calorimetry (DSC) and infrared spectroscopy (FTIR) were chosen to study the influence of ageing conditions. Thermooxidative stability of material was estimated by non-isothermal DSC measurements and changes in the chemical structure were investigated by FTIR analysis. It was found that both UV exposure and presence of NOₓ negatively impact beeswax stability. The kinetic analysis of DSC data revealed significant reduction in the length of oxidation induction periods. After five days’ storage in NOₓ-polluted air (2000 ppm, v/v) the predicted lifetime of beeswax at 23 °C was shortened by more than 60 %. Similar deteriorative effect on stability was observed after 50 h of continuous UV light exposure (4.5 mW/cm²). These results are consistent with that obtained from FTIR analysis where extinction of ester groups accompanied by increase in free fatty acids content was observed.
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