## 3 Results and Discussion
### Oxygen Absorption Capacity  
The oxygen scavenging properties of the systems PE/PA, PE/PA/PB5 and PE/PA/PB13 developed by cast film extrusion were evaluated since the presence of residual oxygen in nut packages results in quick spoilage of fatty products by oxidation of fats. In a preliminary experiment, the O\({}_{2}\) absorbed (%) by PE/PA, PE/PA/PB5 and PE/PA/PB13 films after UV radiation for 5, 10 and 20 h (mean \(\pm\) SD, \(n\) = 3) was evaluated as it is shown in Figure 3. Higher values of absorbed oxygen (%) were obtained as the irradiation time and PB concentration increased. However, the PE/PA film showed no oxygen absorption regardless of the irradiation time. This indicated that the absorption capacity of the films was related to the amount of PB present in the formulation in spite that PA was also present. These results are in line with the ones reported previously by [PERSON] and coworkers ([PERSON] et al., 2019) confirming the oxygen absorption capacity of 1,2-polybutadiene in combination with a transition metal catalyst. To evaluate the impact of the UV radiation on the mechanical properties of the films, the TS (MPa), EB (%) and YM (MPa) of the films after being exposed for 20 h to UV irradiation were measured. In relation to the formulation PE/PA, values of 17 \(\pm\) 1, 157 \(\pm\) 13 and 120 \(\pm\) 20 were obtained, respectively indicating no significant differences in comparison with the same films without having undergone UV treatment. In addition, Figure 4B shows that UV irradiation treatment produced no significant changes in FTIR spectra of PE/PA. When the PB containing films were considered, the obtained values of TS (MPa), EB (%) and YM (MPa) were 18 \(\pm\) 1, 141 \(\pm\) 11 and 140 \(\pm\) 30 for the PE/PA/PB5 and 17 \(\pm\) 2, 180 \(\pm\) 35 and 151 \(\pm\) 20 for the PE/PA/PB13. When comparing these data to those obtained when the films were not irradiated, it could be concluded that 20 h of UV irradiation exposure had no significant impact on the mechanical properties of the films (Table 2). In addition, the UV irradiation treatment produced no significant changes in FTIR spectra of PE/PA/PB5 and PE/PA/PB13 as shown in Figure 4C,D. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline  & **YM (MPa)** & **EaB (\%)** & \begin{tabular}{c} **TS** \\ **(MPa)** \\ \end{tabular}  & \begin{tabular}{c} **TA (CO)** \\ \end{tabular}  & \begin{tabular}{c} **AH\({}_{\rm c}\) **Q g\({}^{-1}\)** \\ \end{tabular}  & \begin{tabular}{c} **TA (CO)** \\ \end{tabular}  & \begin{tabular}{c} **AH\({}_{\rm m}\) **Q g\({}^{-1}\)** \\ \end{tabular}  & \begin{tabular}{c} **TA (CO)** \\ \end{tabular}  & \begin{tabular}{c} **AH\({}_{\rm m}\) **Q g\({}^{-1}\)** \\ \end{tabular}  & \begin{tabular}{c} **TA (CO)** \\ \end{tabular}  & \ \begin{tabular}{c} **TA (CO)** \\ \end{tabular}  & \begin{tabular}{c} **TA (CO)** \\ \end{tabular}  \\ \hline PE & 150 \(\pm\) 20 \({}^{*}\) & 183 \(\pm\) 25 \({}^{*}\) & 18 \(\pm\) 1 \({}^{*}\) & 98 \(\pm\) 0 \({}^{*}\) & 82 \(\pm\) 2 \({}^{*}\) & 108 \(\pm\) 0 \({}^{*}\) & 118 \(\pm\) 2 \({}^{*}\) & 40 \(\pm\) 1 \({}^{*}\) &With the purpose of optimizing the UV irradiation time for each of PB containing formulations, PE/PA/PB5 and PE/PA/PB13, the oxygen absorption capacity (mL O\({}_{2}\) g\({}^{-1}\) film) was measured. To this end, 1 g of 5, 10 and 20 h irradiated film was used in each experiment. The absorbed O\({}_{2}\) volumes were 2.1 \(\pm\) 0.1, 2.7 \(\pm\) 0.3 and 1.8 \(\pm\) 0.2 mL O\({}_{2}\) g\({}^{-1}\) film for the PE/PA/PB5 films irradiated during 5, 10 and 20 h. For the PE/PA/PB13 films, values of 3.4 \(\pm\) 0.3, 3.7 \(\pm\) 0.2 and 3.6 \(\pm\) 0.2 mL O\({}_{2}\) g\({}^{-1}\) film for the 5, 10 and 20 h of UV treatment were achieved. Based on these results and considering that the maximum amount of O\({}_{2}\) present in the vial was 3.8 mL O\({}_{2}\), it can be concluded that 10 h of UV treatment was the optimum treatment time for the formulation with less PB content.